| 1. |
- Aaditya, V. B., et al.
(författare)
-
Study of dielectric properties of polypyrrole/titanium dioxide and polypyrrole/titanium dioxide-MWCNT nano composites
- 2018
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer. - 0957-4522 .- 1573-482X. ; 29:4, s. 2848-2859
-
Tidskriftsartikel (refereegranskat)abstract
- The polypyrrole/titanium dioxide nano composites and polypyrrole/titanium dioxide-MWCNT nano composites were synthesized by chemical polymerization technique in the presence of an ammonium persulphate (oxidizing agent). Different concentrations viz. 15, 30, 45 and 60 wt% of titanium dioxide (TiO2) as well as mixture of TiO2-MWCNT in polypyrrole (PPy) respectively were used in the present study. The nano composites have almost spherical type shaped particles which have cluster formation as confirmed from SEM photos. The XRD graphs reveal that the PPy/TiO2 (PT) nano composites have shown the semi-crystalline nature and also, the graphs indicate the changeover of the structure of PPy/TiO2-MWCNT (PTM) nano composites from amorphous to semi-crystalline nature. From the FTIR figures, shift in wavenumber towards lower side is noticed in the case of PT and PTM nano composites when compared to PPy. The dielectric properties such as dielectric constant, dielectric loss and tangent loss have shown good behavior. This reveals that, the TiO2 as well as mixture of TiO2-MWCNT particles have shown strong dependence on PPy and helps to form good composites. So, the nano composites are good dielectric materials.
|
|
| 2. |
- Abdel-Baset, T. A., et al.
(författare)
-
Effect of metal dopant on structural and magnetic properties of ZnO nanoparticles
- 2021
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer. - 0957-4522 .- 1573-482X. ; 32:12, s. 16153-16165
-
Tidskriftsartikel (refereegranskat)abstract
- Zn1-xRxO (R = Li, Mg, Cr, Mn, Fe and Cd) were obtained by using co-precipitation synthesis technique with constant weight percent of 3% from R ions. The phase composition, crystal structure, morphology, density functional theory (DFT), and magnetic properties were examined to comprehend the influence of Zn2+ partial substitution with R ions. X-ray diffraction shows that the ZnO lattice parameters were slightly affected by R doping and the doped sample crystallinity is enhanced. Our results show that introducing Cr, Mn and Fe along with Mg into ZnO induces a clear magnetic moment without any apparent distortion in the structural morphology. The spatial configuration of dopant atoms is determined from first-principles calculations, giving a better understanding of the position of the dopant atom responsible for the magnetism. The magnetic moments obtained from our calculations are 3.67, 5.0, and 4.33 mu B per dopant atom for Cr, Mn, and Fe, respectively, which agree with the experimental values. While Cr and Fe tend to form clusters, Mn has more propensity to remain evenly distributed within the system, avoiding cluster-derived magnetism.
|
|
| 3. |
- Abdullah, Omed Gh., et al.
(författare)
-
Optical and structural investigation of synthesized PVA/PbS nanocomposites
- 2015
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 26:9, s. 6939-6944
-
Tidskriftsartikel (refereegranskat)abstract
- Polymer nanocomposite based on polyvinyl alcohol (PVA) and lead sulfide (PbS) in the average radius of (1.88-2.23) nm, have been synthesized using the chemical reduction rote and solution casting technique for different concentrations of PbS. The characterization of the polymer nanocomposite films were carried out using UV-visible spectroscopy, SEM, and XRD. The effect of various concentration of PbS NP on the optical properties of the composite has been studied to understand the optimum conditions for the synthesis process. The nanocomposite film shows high UV and visible light absorptions in the wavelength range of (200-500) nm, which correspond to the characteristics of the PbS NPs. The significant decreasing trend of the direct allowed band gap of the nanocomposite was observed upon increasing the Pb source concentration, from (6.27 eV) for pure PVA to (2.34 eV) for 0.04 M PbS concentration, which is much higher than the energy gap of bulk PbS value (0.41 eV). The calculated values of the static refractive index of Cauchy dispersion model were in the range of (1.09-1.20). X-ray diffraction analysis confirmed the cubic nanocrystalline PbS phase formation.
|
|
| 4. |
- Aboulsaad, Mustafa, et al.
(författare)
-
Thermal oxidation of sputtered nickel nano-film as hole transport layer for high performance perovskite solar cells
- 2019
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Nature. - 0957-4522 .- 1573-482X. ; 30:22, s. 19792-19803
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of rapid oxidation temperature on the sputtered nickel (Ni) films to act as a hole transport layer (HTL) for perovskite solar cell (PSCs) was investigated. A nano-sputtered Ni film with a thickness about 100 nm was oxidized at a range of different oxidation temperatures between 350 and 650 °C to work as HTL in an inverted p–i–n configuration. DC Hall measurement in van der Pauw configuration and photoluminescence spectroscopy were used to measure the charge’s mobility and extraction of nickel oxide (NiO) films. The behaviour of the carrier concentration measurements of NiO layers at different oxidation temperatures showed that the Ni layer oxidized at 450 °C had the highest carrier concentration among the other samples. The performance measurements of the fabricated PSCs showed that the nickel oxide hole-transporting layer which has been oxidized at the optimum oxidation temperature of 450 °C has the highest power conversion efficiency (PCE) of 12.05%. Moreover, the characteristic parameters of the optimum cell such as the open-circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) were 0.92 V, 19.80 mA/cm2 and 0.331, respectively.
|
|
| 5. |
- Akbar, F., et al.
(författare)
-
Graphene synthesis, characterization and its applications in nanophotonics, nanoelectronics, and nanosensing
- 2015
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 26:7, s. 4347-4379
-
Tidskriftsartikel (refereegranskat)abstract
- In the last decade, as semiconductor industry was approaching the end of the exponential Moore's roadmap for device downscaling, the necessity of finding new candidate materials has forced many research groups to explore many different types of non-conventional materials. Among them, graphene, CNTs and organic conductors are the most successful alternatives. Finding a material with metallic properties combined with field effect characteristics on nanoscale level has been always a dream to continue the ever-shrinking road of the nanoelectronics. Due to its fantastic features such as high mobility, optical transparency, room temperature quantum Hall effect, mechanical stiffness, etc. the atomically thin carbon layer, graphene, has attracted the industry's attention not only in the micro-, nano-, and opto-electronics but also in biotechnology. This paper reviews the basics and previous works on graphene technology and its developments. Compatibility of this material with Si processing technology is its crucial characteristic for mass production. This study also reviews the physical and electrical properties of graphene as a building block for other carbon allotropes. Different growth methods and a wide range of graphene's applications will be discussed and compared. A brief comparison on the performance result of different types of devices has also been presented. Until now, the main focus of research has been on the background physics and its application in electronic devices. But, according to the recent works on its applications in photonics and optoelectronics, where it benefits from the combination of its unique optical and electronic properties, even without a bandgap, this material enables ultrawide-band tunability. Here in this article we review different applications and graphene's advantages and drawbacks will be mentioned to conclude at the end.
|
|
| 6. |
- Alshgari, Razan A., et al.
(författare)
-
Manipulation of CuO morphology for efficient potentiometric detection of urea via slow nucleation/growth kinetics exerted by mixed solvents
- 2022
-
Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 33, s. 25250-25262
-
Tidskriftsartikel (refereegranskat)abstract
- Controlling the reaction kinetics during the nucleation/growth of cupric oxide (CuO) nanostructures is very critical in order to achieve a specific and well-defined morphology. For this purpose, we have slowed down the reaction speed using a mixed solvent concept and successfully obtained a chain-like morphology of CuO nanostructures using hydrothermal method. The CuO chain-like morphology was synthesized using a 1:1 (v/v) ratio of ethylene glycol and water. The morphology and crystalline features of CuO were studied by scanning electron microscopy (SEM) and powder X-ray diffraction techniques. The high resolution transmission electron microscopy revealed 5 nm crystallite size for the CuO material prepared in the mixed solvents. The obtained results have shown that the prepared CuO chains had a monocline phase, containing only Cu and O as main elements as confirmed by energy dispersive spectroscopy. This unique morphology obtained from mixed solvent process has provided a better surface for the loading of urease enzyme, thus it enabled the development of sensitive and selective urea biosensor in phosphate buffer solution of pH 7.4. The physical adsorption method was used to immobilize urease enzyme onto the nano surface of CuO. The fabricated biosensor based on urease/CuO chains has shown a dynamic linear range from 0.0005 to15 mM with a low limit of detection 0.0001 mM. Additionally, a fast response time aroudn1s, h high selectivity, stability, repeatability, storage time, and reproducibility were observed. The effect of pH and temperature on the potentiometric signal of the developed biosensor was also examined. Importantly, the practical aspects of the fabricated urea biosensor were probed and the obtained percent recovery results revealed an outstanding performance. The strategy of using mixed solvent with equal volume ratio would be useful for the preparation of other metal oxides with improved catalytic properties for a wide range of clinical, biomedical and other related applications.
|
|
| 7. |
- Anghel, Clara, et al.
(författare)
-
A gas phase analysis technique applied to in-situ studies of gas-solid interactions
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 47:10, s. 3440-3453
-
Tidskriftsartikel (refereegranskat)abstract
- An ultrahigh vacuum technique using mass spectrometry for in-situ investigations of gas-solid interactions is described in this paper. Examples of chemical reactions (oxidation, hydration) between solids and gas mixtures, dissociation of gases on solid surfaces, outgassing of solid materials and permeation of gases through membranes are discussed where the experimental arrangement is explained in detail. This Gas Phase Analysis (GPA) technique can be used at temperatures from room temperature to 1200 degrees C and at pressures up to 1 atm. Aspects related to sample preparation, isotopic gas mixture selection, data acquisition, calibration and interpretation of the experimental data are also addressed.
|
|
| 8. |
- Bandara, Tmwj, et al.
(författare)
-
Efficiency enhancement and chrono-photoelectron generation in dye-sensitized solar cells based on spin-coated TiO2 nanoparticle multilayer photoanodes and a ternary iodide gel polymer electrolyte
- 2023
-
Ingår i: Journal of Materials Science-Materials in Electronics. - 0957-4522. ; 34:28
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of the thickness of a multilayer TiO2 photoanode on the performance of a dye-sensitized solar cell (DSC) made with a polyethylene oxide-based gel polymer electrolyte containing ternary iodides and performance enhancer 4-tert-butylpyridine is studied. Multilayer photoanodes consisting of up to seven layers of TiO2 nano-particles (13 nm and 21 nm) are prepared by spin coating of successive layers. XRD results confirm the predominant presence of the anatase phase of TiO2 in the multilayer structure after sintering. The SEM images reveal the formation of a single TiO2 film upon sintering due to merging of individually deposited layers. The photocurrent density (J(SC)) and the efficiency increase with the number of TiO2 layers exhibiting the maximum efficiency and J(SC) of 5.5% and 12.5 mA cm(-2), respectively, for the 5-layered electrode of total thickness 4.0 mu m with a 9.66 x 10(-8) mol cm(-2) surface dye concentration. The present study introduces a method of determining the rate of effective photoelectron generation and the average time gap between two successive photon absorptions where the respective results are 1.34 molecule(-1) s(-1) and 0.74 s for the most efficient cell studied in this work.
|
|
| 9. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Novel photo-voltaic device based on Bi_{1−x}La_xFeO_3 perovskite films with higher efficiency
- 2019
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 30:2, s. 1654-1662
-
Tidskriftsartikel (refereegranskat)abstract
- Photovoltaic cells using polycrystalline La substituted bismuth iron oxide, Bi1−xLaxFeO3, (0.1 ≤ x ≤ 0.4), films as the light harvesting component were investigated in this work. A novel cell set-up utilizing a double layered TiO2 film as top contact and a thin layer of quasi-solid polymer electrolyte as back contact was used and a significant enhancement in cell efficiency was observed for assemblies based on x ≥ 0.2 samples, coincident with a structural transition of Bi1−xLaxFeO3 from ferroelectric to non-ferroelectric. The power conversion efficiency of the PV device was 0.13% for the cell with x = 0.2 at 1 sun irradiation. The short circuit current density for this La composition was 0.35 mA cm−2. A hysteretic behaviour was observed for higher La compositions when the scanning is from open-circuit (OP) to short-circuit (SC) which may be attributed to polarization effects. The results at x ≥ 0.2 show an improved performance with respect to BiFeO3 based systems, suggesting the stabilization of the non-ferroelectric crystal structure leads either to a more efficient separation of photo-generated electron–hole pairs and/or enhanced charge transport. The findings represent a step towards the realisation of facile to fabricate, inorganic solid state photovoltaic devices.
|
|
| 10. |
- Bandara, Tmwj, et al.
(författare)
-
Novel photo-voltaic device based on Bi1-xLaxFeO3 perovskite films with higher efficiency
- 2019
-
Ingår i: Journal of Materials Science-Materials in Electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 30:2, s. 1654-1662
-
Tidskriftsartikel (refereegranskat)abstract
- Photovoltaic cells using polycrystalline La substituted bismuth iron oxide, Bi1-xLaxFeO3, (0.1x0.4), films as the light harvesting component were investigated in this work. A novel cell set-up utilizing a double layered TiO2 film as top contact and a thin layer of quasi-solid polymer electrolyte as back contact was used and a significant enhancement in cell efficiency was observed for assemblies based on x0.2 samples, coincident with a structural transition of Bi1-xLaxFeO3 from ferroelectric to non-ferroelectric. The power conversion efficiency of the PV device was 0.13% for the cell with x=0.2at 1 sun irradiation. The short circuit current density for this La composition was 0.35mAcm(-2). A hysteretic behaviour was observed for higher La compositions when the scanning is from open-circuit (OP) to short-circuit (SC) which may be attributed to polarization effects. The results at x0.2 show an improved performance with respect to BiFeO3 based systems, suggesting the stabilization of the non-ferroelectric crystal structure leads either to a more efficient separation of photo-generated electron-hole pairs and/or enhanced charge transport. The findings represent a step towards the realisation of facile to fabricate, inorganic solid state photovoltaic devices.
|
|
| 11. |
- Beshkova, Milena, et al.
(författare)
-
Sublimation epitaxy of AIN layers on 4H-SiC depending on the type of crucible
- 2003
-
Ingår i: Journal of materials science. Materials in electronics. - 0957-4522 .- 1573-482X. ; 14:10-12, s. 767-768
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of aluminum nitride less than or equal to335 mum thick have been grown attemperatures of 1900 and 2100degreesC on 10 x 10 mm(2) (0001)-oriented alpha(4H) silicon carbide (SiC), with growth times of 1 and 4h, via sublimation-recondensation in a RF-heated graphite furnace. The source material was polycrystalline AIN. The sublimation process was performed in three types of graphite (C) crucible: C-1, C-2 with inner diameters of 35 and 51 mm, respectively, and C-3 with the same inner diameter as C-1, but coated with a layer of TaC. The surface morphology reflects the hexagonal symmetry of the substrate, suggesting an epitaxial growth for samples grown in C-1 and C-3 crucibles for all growth conditions. The same symmetry is observed for AIN layers grown in the C-2 crucible, but only at 2100degreesC. X-ray diffraction analyses confirm the epitaxial growth of AIN samples with the expected hexagonal symmetry. A high-resolution X-ray diffractometer was used to assess the quality of the single crystals. A full width at half maximum of 242 arcsec was achieved for an AIN layer grown in the crucible coated with TaC. (C) 2003 Kluwer Academic Publishers.
|
|
| 12. |
- Borchert, Dietmar, et al.
(författare)
-
Interaction between process technology and material quality during the processing of multicrystalline silicon solar cells
- 2009
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 20:1, s. 487-492
-
Tidskriftsartikel (refereegranskat)abstract
- Multicrystalline silicon is the most used materialfor the production of silicon solar cells. The quality of the asgrown material depends on the quality of the feedstock andthe crystallization process. Bulk impurities, crystal defectslike dislocations and of course the grain boundaries determinethe material quality and thus the solar cell conversionefficiency. Therefore minority carrier lifetime measurementsare often done to characterize the material quality. Butthe measured values are from limited use because it is knownthat the solar cell process itself can dramatically change theminority carrier lifetime and the solar cell efficiency. In orderto obtain more detailed information of the behaviour ofdifferent defect types additionally high-resolution LBIC(light beam induced current)-measurements have been done.Since LBIC needs a pn-junction for photocurrent generationthe LBIC technique has been combined with the a-Si/c-Siheterojunction cell process, which makes it possible tomanufacture solar cells even from as cut wafers withoutchanging the material quality. With this combination ofmeasurement and preparation techniques it was possible toanalyze the influence of the diffusion process and the firingprocess on the behaviour of the three different defect types: grain boundaries, dislocation networks and bulk impurities.
|
|
| 13. |
|
|
| 14. |
- Carvalho, A., et al.
(författare)
-
Oxygen defects in irradiated germanium
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 781-786
-
Tidskriftsartikel (refereegranskat)abstract
- The defects present in oxygen-rich irradiated germanium have been extensively characterised from an experimental point of view. Here, we summarise recent theoretical findings obtained using the cluster method and discuss their relation with the experimental data. In order to find a microscopic interpretation of the reactions taking place in this material upon annealing up to 400°C, we performed nudged elastic band (NEB) calculations of the migration and dissociation paths of VO, as well as a modelling of other oxygen-related complexes that are expected to form in this temperature range. Energy barriers of 1.5 (1.1) eV and 1.2 (0.9) eV for the dissociation and migration of the neutral (negatively charged) VO defect are found. We compare these with the activation energies estimated from the analysis of Hall effect, deep level transient spectroscopy (DLTS) and infra-red (IR) spectroscopy annealing data reported in literature.
|
|
| 15. |
- Cedervall, Johan, et al.
(författare)
-
On the structural and magnetic properties of the double perovskite Nd2NiMnO6Nd2NiMnO6
- 2019
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 30:17, s. 16571-16578
-
Tidskriftsartikel (refereegranskat)abstract
- The structural, electronic and magnetic properties of phase pure and stoichiometric samples of the double perovskite Nd 2NiMnO 6 have been investigated with a combination of X-ray and neutron diffraction, X-ray photoelectron spectroscopy and magnetometry. It is found that the monoclinic space group P2 1/ n best describes the crystal structure of Nd 2NiMnO 6. Photoectron spectroscopy revels a mixed valence of the transition metal sites where Ni has 3+/2+ oxidation states and Mn has 3+/4+. The compound orders ferromagnetically at ∼195 K. The magnetic structure was determined from the refinement of the neutron diffraction data. The results suggests that the B-site magnetic moments align along the crystallographic a-direction.
|
|
| 16. |
- Coutinho, Jose, et al.
(författare)
-
Early stage donor-vacancy clusters in germanium
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 769-773
-
Tidskriftsartikel (refereegranskat)abstract
- There is considerable experimental evidence that vacancies in Ge dominate several solid state reactions that range from self-diffusivity to metal and dopant transport. It is therefore vital that we fully understand how vacancies interact with other point defects in Ge. Here we have a look at the properties of small donor-vacancy (Sb n V m with m,n ≤ 2) complexes in Ge by ab-initio density functional modeling. Particular attention has been payed to binding energies and to the electronic activity of the complexes. We found that all aggregates may contribute to the n→ p type conversion that is typically observed under prolonged MeV irradiation conditions. In general, Sb n V m defects are double acceptors. It is also suggested that spontaneous formation of Sb3V complexes may limit the activation level of donors introduced by ion implantation.
|
|
| 17. |
- Dhawale, D, et al.
(författare)
-
Synthesis and characterizations of CdS nanorods by SILAR method : effect of film thickness
- 2011
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer. - 0957-4522 .- 1573-482X. ; 46, s. 5009-5015
-
Tidskriftsartikel (refereegranskat)abstract
- In this investigation, we have successfully synthesized CdS nanorods by simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. The effect of film thickness on the physico-chemical properties such as structural, morphological, wettability, optical, and electrical properties of CdS nanorods has been investigated. The XRD pattern revealed that CdS films are polycrystalline with hexagonal crystal structure. SEM and TEM images showed that CdS film surface are composed of spherical grains along with some spongy cluster and an increase in film thickness up to 1.23 μm causes the formation of matured nanorods having diameter 150–200 nm. The increases in water contact angle form 105° to 130° have been observed as film thickness increases from 0.13 to 1.23 μm indicating hydrophobic nature. The optical band gap was found to be increased from 2.02 to 2.2 eV with increase in film thickness. The films showed the semiconducting behavior with room temperature electrical resistivity in the range of 104–106 Ω cm and have n-type electrical conductivity.
|
|
| 18. |
- Dhumal, Jyoti, et al.
(författare)
-
Enhanced heating ability of Fe–Mn–Gd ferrite nanoparticles for magnetic fluid hyperthermia
- 2020
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 31, s. 11457-11469
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reveals the structural, magnetic and heating ability of citric acid coated Fe0.3Mn0.7GdxFe2−xO4 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) nanocrystalline ferrites. The synthesis of Gd-doped Fe–Mn ferrite nanoparticles (NPs) is confirmed by XRD studies. Substitution of Gd3+ions in Fe–Mn ferrite causes the lattice constant enhancement from 8.3286 to 8.4699 Å. The cation distribution reveals that Gd3+ ions preferred the octahedral sites of Fe–Mn ferrite. The average crystallite size is around 10–12 nm. The Fe–Mn–Gd spinel ferrite NPs are also characterized by FTIR studies and supports its formation. The saturation magnetization increases with Gd-content, take its maximum value for x = 0.06 and drops further for higher x values. The change in saturation magnetization show a connection with the structural modifications; because of replacement of Gd3+ ions at the place of Fe3+ ions in the octahedral site (B-site), it modifies A and B sublattices superexchange interactions. The heating abilities of these nanoparticles are studied by applying different alternating magnetic fields at constant frequency 289 kHz. When referred to the Gd-content, the SAR exhibits similar variation as saturation magnetization (Ms) and anisotropy constant (K), the later being more dominant. The highest value of SAR is 640 W/g for Fe0.3Mn0.7Gd0.06Fe1.94O4 sample under an applied field 251.4 Oe. It is seen that SAR is increased by nearly six times as compared to pristine Fe0.3Mn0.7Fe2O4 nanoparticles. The present results suggest that magnetic field controlled therapeutic temperature can be easily achieved within 1 min using such nanoparticles.
|
|
| 19. |
- Dong, H., et al.
(författare)
-
Effect of powder characteristics on the thermal conductivity and mechanical properties of Si 3 N 4 ceramics sintered by Spark plasma sintering
- 2019
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer-Verlag New York. - 0957-4522 .- 1573-482X. ; 30:8, s. 7590-7599
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of powder characteristics on the thermal conductivity and mechanical properties of silicon nitride (Si 3 N 4 ) ceramics were investigated systematically by using two α-Si 3 N 4 powders as raw materials and using MgSiN 2 or MgO + Y 2 O 3 as sintering additives. The Si 3 N 4 ceramics with a higher density were obtained by α-Si 3 N 4 powders with lower oxygen content and impurities and using none-oxide sintering additive MgSiN 2 . The α–β phase transformation completely taken place in all the specimen at 1750 °C. The specimens sintered by powders with lower levels of oxygen and impurities show higher mechanical properties than other specimens. The Y 2 O 3 and MgO sintering additives lead to higher flexural strength and fracture toughness than MgSiN 2 . The Vickers’ hardness is just the opposite. The thermal conductivity value of powders with lower oxygen content is higher than that of the materials prepared by the other type of powder at the same conditions. The effects of the Si 3 N 4 particle size, native oxygen and impurities on the thermal conductivity of resultant materials were discussed in detail. This work demonstrates that the improvement in thermal conductivity of Si 3 N 4 can be obtained by using none-oxide sintering additive MgSiN 2 and the Si 3 N 4 powder with lower oxygen content, and impurities.
|
|
| 20. |
- Efavi, J K, et al.
(författare)
-
Tungsten work function engineering for dual metal gate nano-CMOS
- 2005
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 16:7, s. 433-436
-
Tidskriftsartikel (refereegranskat)abstract
- A buffer layer technology for work function engineering of tungsten for dual metal gate Nano-CMOS is investigated. For the first time, tungsten is used as a p-type gate material using 1 nm of sputtered Aluminum Nitride (AlNx) as a buffer layer on silicon dioxide (SiO2) gate dielectric. A tungsten work function of 5.12 eV is realized using this technology in contrast to a mid-gap value of 4.6 eV without a buffer layer. Device characteristics of a p-MOSFET on silicon-on-insulator (SOI) substrate fabricated with this technology are presented.
|
|
| 21. |
- Engelbrecht, J. A. A., et al.
(författare)
-
Comparison of experimental results with theoretical models for the temperature dependence of the band gap of AlxGa1-xN epilayers
- 2022
-
Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 33, s. 22492-22498
-
Tidskriftsartikel (refereegranskat)abstract
- The band gap energies AlxGa1-xN epilayers prepared on two different substrates were assessed using Fourier Transform Infrared (FTIR) reflectance spectroscopy, photoluminescence (PL) and scanning electron microscopy electron dispersive spectroscopy (SEM-EDS). The results were compared to various theoretical formulae to calculate the band gap, and deviations elucidated.
|
|
| 22. |
- Evtimova, S, et al.
(författare)
-
Effect of carrier concentration on the microhardness of GaN layers
- 2003
-
Ingår i: Journal of materials science. Materials in electronics. - 0957-4522 .- 1573-482X. ; 14:10-12, s. 771-772
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents a microhardness study of thick crack-free hydride vapor phase epitaxial GaN layers (not intentionally doped), and of thin metal-organic vapor phase epitaxial (MOVPE) GaN layers (undoped and Si-doped), grown on sapphire. A Vickers indentation method was used to determine the microhardness under applied loads up to 2 N. An increase in the microhardness was observed with decreasing carrier concentration and increasing mobility. A dip at an indentation depth of about 0.75 mum is observed in the microhardness profile in the MOVPE films, and is correlated with peculiarities in the spatially resolved cathodoluminescence spectra. The relationship between the mechanical and electrophysical parameters is discussed. (C) 2003 Kluwer Academic Publishers.
|
|
| 23. |
- Fujita, Naomi, et al.
(författare)
-
Local vibrational modes of N2-O n defects in Cz-Silicon
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 683-687
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we investigate N2-O n defect complexes in Czochralski silicon (Cz-Si) by means of local density functional theory. We consider the N2O and the N2O2 defect and determine their structural, electronic and vibrational properties. The calculated local vibrational modes of the N2O defect are in good agreement with the experiment. Furthermore the calculated binding energy matches very well with the experimental estimate. Motivated by recent experimental work, where several new absorption lines in IR absorbance spectra were observed, we present first principle studies on the ground state configuration, binding energy and local vibrational modes of the N2O2 defect and make a tentative assignment to the experimentally observed lines at 1018 and 810 cm-1.
|
|
| 24. |
- Ghandi, Reza, et al.
(författare)
-
High boron incorporation in selective epitaxial growth of SiGe layers
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 747-751
-
Tidskriftsartikel (refereegranskat)abstract
- Incorporation of high amount of boron in the range of 1 x 10(20)-1 x 10(21) cm(-3) in selective epitaxial growth (SEG) of Si1-xGex (x = 0.15-0.315) layers for recessed or elevated source/drain junctions in CMOS has been studied. The effect of high boron doping on growth rate, Ge content and appearance of defect in the epi-layers was investigated. In this study, integration issues were oriented towards having high layer quality whereas still high amount of boron is implemented and the selectivity of the epitaxy is preserved.
|
|
| 25. |
- Gomaa, M. M., et al.
(författare)
-
Exploring NiO nanosize structures for ammonia sensing
- 2018
-
Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 29:14, s. 11870-11877
-
Tidskriftsartikel (refereegranskat)abstract
- Efficient ammonia gas sensor devices were fabricated based on nickel oxide (NiO) nanostructures films. Two chemical synthesis approaches were used: chemical spray pyrolysis (CSP) and chemical bath deposition (CBD), aiming at obtaining highly developed surface area and high chemical reactivity of NiO. Crystal structure, morphology, and composition of NiO films and nanostructures were investigated by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. CSP method results in the synthesis of NiO films with pure cubic crystalline structure of preferred orientation along (111) direction. The type of the precursors used (nickel acetate, nickel chloride and nickel nitrate) affects the morphology and crystallites average size of the deposited films. CBD method consisted of two stages: (i) deposition of nickel hydroxide phase and (ii) thermal annealing of nickel hydroxide at 450 A degrees C in air for 4 h. Resulted structures were nanoflakes, vertically arranged in a "wall-like" morphology. Fabricated structures were found to be sensitive to ammonia differently, depending on the synthesis approach and material morphology. NiO films deposited by CBD demonstrated a stable response to ammonia with maximum magnitude at the operating temperature of 300 A degrees C. The highest average response for the CBD-NiO sample was 114.3-141.3% for 25 and 150 ppm NH3, respectively, whereas the response range observed for the film processed by spray pyrolysis using nickel chloride was 31.7-142.5% for 25 and 150 ppm NH3, respectively.
|
|
| 26. |
- Haghighatzadeh, Azadeh, et al.
(författare)
-
Facile synthesis of ZnS-Ag2S core-shell nanospheres with enhanced nonlinear refraction
- 2020
-
Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 31:2, s. 1283-1292
-
Tidskriftsartikel (refereegranskat)abstract
- ZnS-Ag2S core-shell nano/hetero-junctions have been synthesized by a two-step co-precipitation technique, in which thin layers of -Ag2S have been successfully coated on the surface of ZnS nanospheres. Structural studies and elemental analysis have been performed using X-ray diffraction, Fourier transfer infrared spectroscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, and high-resolution transmission electron microscopy. UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy have been employed to investigate linear optical characteristics. Nanosecond laser pulsed-based single-beam Z-scan analysis has been used to examine the magnitude and the sign of the third-order nonlinear refractive indices. Samples show negative values of nonlinear refractive indices indicating self-defocusing optical nonlinearity under 1064 nm excitation. The results have shown that the third-order nonlinear refractive index in ZnS nanospheres can reach the magnitude of 61.0 x 10-12 m2/W by encapsulating such a nanostructure within nanometer shells of -Ag2S. The enhanced nonlinearity for ZnS-Ag2S core-shells has been found to be 9 times higher than sole ZnS nanoparticles, which was estimated to be about 6.4 x 10-12 m2/W.
|
|
| 27. |
- Haghighatzadeh, A., et al.
(författare)
-
Hollow ZnO microspheres self-assembled from rod-like nanostructures : morphology-dependent linear and Kerr-type nonlinear optical properties
- 2021
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Nature. - 0957-4522 .- 1573-482X. ; 32:18, s. 23385-23398
-
Tidskriftsartikel (refereegranskat)abstract
- Hollow nanostructures have attracted attention because of their unique physiochemical properties and broad potential applications in electronics, optics and photonics. In this study, a facile hydrothermal approach was developed to fabricate hollow ZnO microspheres via self-assembled rod-like nanostructures. The morphology-controlled synthesis was conducted by altering hydrothermal treatment temperature (150, 200 and 250 °C) in solutions containing zinc acetate dihydrate precursor and glycerol as the stabilizing agent. The morphological observations indicated that hydrothermally grown ZnO architectures could be reasonably adjusted by modulating hydrothermal reaction temperature. Possible growth routes are proposed to elucidate the formation process of ZnO microspheres with the rod-like nanostructures. Morphology-dependent absorbance and emission along with red-shifts with improved crystalline qualities were observed with increasing hydrothermal growth temperature. Kerr-type nonlinear optical characteristics examined using single-beam Z-scan technique in the near infrared spectral range under nanosecond Nd-YVO4 laser pulses showed positive values of nonlinear refraction providing an evidence of self-focusing behaviors at the excitation wavelength of 1064 nm in all the samples studied. The highest Kerr-type nonlinear susceptibility was estimated to be 2.31 × 10–6 esu for hollow ZnO microspheres grown at 250 °C, suggesting synergistic effects of surface morphologies on optical nonlinearities.
|
|
| 28. |
- Hait, S., et al.
(författare)
-
Impact of ferromagnetic layer thickness on the spin pumping in Co60Fe20B20/Ta bilayer thin films
- 2021
-
Ingår i: Journal of Materials Science-Materials in Electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 32, s. 12453-12465
-
Tidskriftsartikel (refereegranskat)abstract
- We report the tuneable spin angular momentum transfer (spin pumping) from Co60Fe20B20 (CFB) amorphous alloy into the Ta heavy metal nanolayers. All the films are grown on Si (100) substrate at room temperature using ion-beam sputtering technique. Structural studies reveal that the grown Ta films over amorphous CFB are crystalline even at ultrathin regime. The bilayers possess very low interface roughness (< 0.5 nm) and are continuous throughout the thickness range. Comparative analysis of the spin pumping in CFB (4, 6 and 8 nm) as a function of the Ta thickness (vary from 1 to 10 nm in step of 1 nm) has been performed employing ferromagnetic resonance (FMR) spectroscopy. It is observed that the effective damping increase exponentially with the increase of Ta, (i.e. follows ballistic spin transport) in two series of CFB (4 nm)/Ta (0-10 nm) and CFB(6 nm)/Ta (0-10 nm) bilayers, which is characteristic of normal spin pumping. However, the anomalous behaviour has been observed for CFB (8 nm)/Ta (0-10 nm) bilayer series where the spin current generated in Ta with the thicker CFB behaves oppositely. The results demonstrate the strong dependence of ferromagnet thickness on the spin pumping into the Ta nanolayers. This study paves the way to choose suitable ferromagnetic layer thickness for spin current-induced switching applications in spintronics.
|
|
| 29. |
- Harshitha, R., et al.
(författare)
-
Studies of thermo-electric power and dielectric modulus of polypyrrole/zirconium oxide-molybdenum trioxide (PZM) composites
- 2018
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 29:8, s. 6564-6578
-
Tidskriftsartikel (refereegranskat)abstract
- Zirconium oxide-molybdenum trioxide doped polypyrrole composites have been synthesized in the presence of ammonium persulphate (oxidizing agent), with different 15, 30, 45 and 60 wt% of zirconium oxide-molybdenum trioxide (ZM) in pyrrole, by the chemical polymerization (oxidation) process. The polypyrrole/zirconium oxide-molybdenum trioxide (PZM) composites have exhibited crystalline nature, which has been confirmed by powder X-ray diffraction patterns. The Fourier transform infrared graphs show that the stretching frequencies of the composites have shifted towards the lower frequency side. The scanning electron microscopy micrographs indicate that the composites are of spherical nature and form elongated chains; an increase in the particles size when compared with polypyrrole and ZM particles is also observed. Thermo electric power and transport properties studies reveal that there is an interaction between polypyrrole and the ZM particles and the weight percents of the ZM particles have an influence on the properties of the pure polypyrrole. Studies shown that, the PZM composites are good materials in conductivity, dielectric properties, micro power generator, thermo cooling, as semiconductors as well as may be in humidity, gas and thermal sensor. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
|
|
| 30. |
- Huerta-Flores, Ali M., et al.
(författare)
-
Extended visible light harvesting and boosted charge carrier dynamics in heterostructured zirconate-FeS2 photocatalysts for efficient solar water splitting
- 2018
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 29:22, s. 18957-18970
-
Tidskriftsartikel (refereegranskat)abstract
- Limited visible light absorption, slow charge transference, and high recombination are some of the main problems associated with low efficiency in photocatalytic processes. For these reasons, in the present work, we develope novel zirconate-FeS2 heterostructured photocatalysts with improved visible light harvesting, effective charge separation and high photocatalytic water splitting performance. Herein, alkali and alkaline earth metal zirconates are prepared by a solid state reaction and coupled to FeS2 through a simple wet impregnation method. The incorporation of FeS2 particles induces visible light absorption and electron injection in zirconates, while the appropriate coupling of the semiconductors in the heterostructure allows an enhanced charge separation and suppression of the recombination. The obtained heterostructures exhibit high and stable photocatalytic activity for water splitting under visible light, showing competitive efficiencies among other reported materials. The highest hydrogen evolution rate (4490 mu molg(-1)h(-1)) is shown for BaZrO3-FeS2 and corresponds to more than 20 times the activity of the bare BaZrO3. In summary, this work proposes novel visible light active heterostructures for efficient visible light photocatalytic water splitting.
|
|
| 31. |
- Huerta-Flores, Ali M., et al.
(författare)
-
Green synthesis of earth-abundant metal sulfides (FeS2, CuS, and NiS2) and their use as visible-light active photocatalysts for H2 generation and dye removal
- 2018
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 29:13, s. 11613-11626
-
Tidskriftsartikel (refereegranskat)abstract
- Earth-abundant metal sulfides (for example, FeS2, CuS, and NiS2) are promising materials to be used as photocatalysts due to their suitable electronic and optical properties. In this work, we present a fast and low-cost hydrothermal method to synthesize these materials. They are integrally characterized and evaluated as photocatalysts for the H2evolution reaction and the degradation of indigo carmine (IC). FeS2exhibits the highest photocatalytic efficiency (32 µmol g−1 h−1of H2evolution and 88% of indigo carmine degradation) under visible light, and this activity is attributed to a larger crystallite size, smaller particle size, and lower recombination, compared to CuS and NiS2. Moreover, three different sacrificial reagents are studied for the H2evolution reaction, including Na2S/Na2SO3, EDTA, and ethanol. Na2S/Na2SO3shows the highest enhancement in the activity, increasing the rate of H2production more than 15 times. This behavior is related to the lower oxidation potential of Na2S/Na2SO3. Moreover, we evaluate the activity of the materials for the electrochemical hydrogen evolution reaction (HER). In summary, this work provides valuable information for effective applications of these earth-abundant metal sulfides for energy and environmental photocatalytic processes.
|
|
| 32. |
- Ivanov, Sergey A., et al.
(författare)
-
Composition dependence of the multifunctional properties of Nd-doped Bi4Ti3O12 ceramics
- 2017
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 28:11, s. 7692-7707
-
Tidskriftsartikel (refereegranskat)abstract
- Sample preparation, evolution of the crystal structure with Nd content at room temperature, as well as dielectric and magnetic properties of polycrystalline Bi4-xNdxTi3O12 solid solutions (x = 0.0, 0.5, 1.0, 1.5, and 2.0) are reported. These solid solutions were structurally characterized by X-ray powder diffraction using Rietveld refinements. For x <= 1.0, the samples crystallize in an orthorhombic symmetry. The structural data could be refined using the polar orthorhombic space group B2cb. The orthorhombicity decreases with increasing Nd3+ concentration, and a paraelectric tetragonal structure (space group I4/mmm) is stabilized for x > 1. The ferroelectric Curie temperature was found to monotonously decrease with increasing Nd concentration. A polar-to-nonpolar phase transition takes place near x = 1, reflecting the existence of a morphotropic phase boundary between 1.0 < x < 1.5 at room temperature. All samples were found to be paramagnetic down to 5 K, however, the presence of significant antiferromagnetic interaction is inferred from Curie-Weiss analyses of the temperature dependence of the magnetic susceptibility of the doped samples. The effect of Nd3+ substitution on structure-property relationship is discussed and compared to that of other lanthanide cations.
|
|
| 33. |
- Ivanov, Sergey A., et al.
(författare)
-
Spin and dipole order in geometrically frustrated mixed-valence manganite Pb3Mn7O15
- 2016
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 27:12, s. 12562-12573
-
Tidskriftsartikel (refereegranskat)abstract
- The structural, magnetic, and dielectric properties of Pb3Mn7O15 have been investigated using high-quality single crystals. Pb3Mn7O15 adopts a pseudo-hexagonal orthorhombic structure, with partially filled Kagom, layers connected by ribbons of edge-sharing MnO6 octahedra and intercalated Pb cations. There are 9 inequivalent sites in the structure for the Mn ions, which exist both as Mn3+ and Mn4+. Pb3Mn7O15 undergoes an antiferromagnetic transition below T-N similar to 67 K, with significant geometric frustration. Neutron powder diffraction on crushed single crystals allowed us to determine the low-temperature antiferromagnetic magnetic structure. We discuss the magnetic interaction pathways in the structure and possible interplay between the structural distortions imprinted by the lone-electron pair of Pb2+ cations and Mn3+/Mn4+ charge ordering.
|
|
| 34. |
- Ivanov, Sergey, et al.
(författare)
-
Temperature-dependent structural and magnetic properties of R2MMnO6 double perovskites (R=Dy, Gd; M=Ni, Co)
- 2018
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 29:21, s. 18581-18592
-
Tidskriftsartikel (refereegranskat)abstract
- The structural and magnetic properties of the Dy2CoMnO6, Dy2NiMnO6 and Gd2CoMnO6 double perovskites are investigated using X-ray powder diffraction and squid magnetometry. The materials adopt an orthorhombic structure (space ground Pnma) with disordered Co(Ni)/Mn cations, and exhibit ferrimagnetic transitions near T(C)85, 95, and 115K respectively. T-C was found to monotonously depend on the orthorhombic distortion (a-c)/(a+c) of the compounds. The crystal structure of the compounds was investigated as a function of temperature (16-1100K range), evidencing changes in the BO6 octahedron near T-C. The magnetic entropy changes are estimated for comparison of the magnetocaloric properties to those from literature.
|
|
| 35. |
- Jain, Anupriya, et al.
(författare)
-
Studies of hypro-mellose (HPMC) functionalized ZnS:Mn fluorescent quantum dots
- 2017
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 28:2, s. 1931-1937
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescent ZnS:Mn quantum dots coated with hypro-mellose (HPMC) were synthesized by using simple and facile chemical precipitation technique in which HPMC acts as a novel organic surfactant to passivate the surface, to tune the optical properties and also to functionalize the surface of quantum dot for a futuristic controlled drug release applications. Morphological and optical characterizations were done to see the effect of HPMC coating on ZnS: Mn quantum dots. Structural and morphological studies was done by using XRD and TEM respectively. XRD studies confirms the pure zinc blende phase for all the samples. TEM studies shows that HPMC is efficiently doing the surface passivation in doped quantum dots. Optical studies were done by using UV-visible, FTIR and time resolved photoluminescence. UV-visible studies shows that quantum confinement effect is more prominent and also tunable in case of HPMC coated manganese doped ZnS quantum dots. FTIR studies confirms the functionalization of HPMC on the surface of doped ZnS quantum dots. Laser induced time resolved photoluminescence studies were also done to see the effect of HPMC on the photoluminescence intensity of doped quantum dots. Time resolved studies clearly shows the much desired luminescence stability of the HPMC coated quantum dots. It is observed that both the structural and optical characteristics have strong dependence on capping concentration. As HPMC is a very important viscoelastic polymer and organic surfactant used in various types of drug formulations, these studies opens a new way in the area of efficient drug delivery, controlled drug release and targeting.
|
|
| 36. |
- Janke, C., et al.
(författare)
-
Ab initio investigation of boron diffusion paths in germanium
- 2007
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 775-780
-
Tidskriftsartikel (refereegranskat)abstract
- Boron is observed to diffuse very slowly in germanium, as opposed to its behaviour in silicon where it exhibits Transient Enhanced Diffusion effects in implanted samples. As a result of this slow diffusion, boron is a very stable dopant, allowing devices to be created with very well-defined doping regions. To understand this superior performance, calculations were performed on a variety of boron diffusion paths, within vacancy and interstitial mediated methods. It was found that the vacancy mediated diffusion which is associated with the fast diffusion of many other species in germanium exhibits a total barrier of 5.8 eV. Interstitial-mediated diffusion had a total barrier for migration of 3.4 eV in the neutral and singly negative charge states, 3.2 eV for the positive charge state, but a formation barrier of 4.1 eV. Thus the barrier for interstitial-mediated diffusion is dominated by the formation energy of the self-interstitial.
|
|
| 37. |
- Jlassi, Khouloud, et al.
(författare)
-
Highly sensitive humidity sensor based on cadmium selenide quantum dots-polymer composites : synthesis, characterization, and effect of UV/ozone treatment
- 2023
-
Ingår i: Journal of Materials Science: Materials in Electronics. - 0957-4522. ; 34:21
-
Tidskriftsartikel (refereegranskat)abstract
- This work describes the rational design of thin film-based cadmium selenide quantum dots (CdSe) mixed with conductive polyvinylidene fluoride (PVDF), inducing PVDF-CdSe composite for potential resistive humidity-sensing applications. The effect of UV/ozone treatment on surface hydrophilicity and sensing properties was investigated. AFM has been performed to examine the prepared films' texture, distribution over the surface, and size. Overall, the hydrophilicity of the developed films increases with UV radiation exposure time, leading to enhanced water vapor absorption without deforming the film surface. The sensor's sensitivity is improved with increasing UV radiation exposure. The electrical response of the PVDF-CdSe humidity sensors after 30 min of UV/ozone treatment reveals that at higher humidity levels (i.e., > 80% RH), the sensors exhibit an irregular response. However, at 20 min, treatment increases sensitivity and a linear change in impedance response concerning humidity level change compared to other samples. The hysteresis response was divided into two regions: the lower region, between 30 and 60% RH—where the maximum hysteresis loss was calculated to be 3%. While the higher area between 60 and 90% RH, where the maximum estimated hysteresis loss of the PVDF-CdSe sensor is around 14%, the UV/ozone treatment of the PVDF-CdSe nanocomposite film was found to enhance the sensing film's hydrophilicity without deforming the surface of the as-prepared PVDF-CdSe as well as the UV-treated films validates a potential for novel humidity sensors.
|
|
| 38. |
- Kaur, A., et al.
(författare)
-
Correlation between reduced dielectric loss and charge migration kinetics in NdFeO3-modified Ba0.7Sr0.3TiO3 ceramics
- 2021
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Nature. - 0957-4522 .- 1573-482X. ; 32:20, s. 24910-24929
-
Tidskriftsartikel (refereegranskat)abstract
- The present study demonstrates the reduction in the dielectric loss at room temperature from 0.149 to 0.027 in the composite of (NdFeO3)0.1−(Ba0.7Sr0.3TiO3)0.9 as compared to the undoped Ba0.7Sr0.3TiO3 and correlates with the charge compensation due to the ionic substitutions for both A site (NdBa) and B (FeTi) site generated excess electrons, localized hole states and robust oxygen vacancies (VO) along with different cationic oxidation states. The VO mediated F center charge transfer mechanism i.e., bound magnetic polaronic behaviour and defect complex generated between acceptors and ionized VO reduce electrical conductivity and loss factor. The presence of weak ferromagnetism in the M-H loop reconfirms the F center exchange mechanism in mixed phase symmetry. The activation energy calculated from impedance spectroscopy, electrical modulus and electrical conductivity analysis supports the presence of doubly ionized VO. Further, density functional theory based first principle calculation manifests that the impurity induced depopulation of valence band edge electrons into a single spin up channel which distorts TiO6 octahedra with fluctuating bond length and Ti 3deg orbital splitting observed in decomposed density of states for accommodating excess electrons. These trapped and accommodated electrons reduce the effective electron concentration which in turn decreases the electrical conductivity and loss factor.
|
|
| 39. |
- Kermaniha, M., et al.
(författare)
-
Systematic optimization of phosphorous diffusion for solar cell application
- 2016
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer-Verlag New York. - 0957-4522 .- 1573-482X. ; 27:12, s. 13086-13092
-
Tidskriftsartikel (refereegranskat)abstract
- Fossil fuel storage is running low and scientists around the globe are involved in a big search for an optimized substitute. Photovoltaic is one of the most likely alternatives to solve this issue and replace the fossil fuels. Among all types of cells, silicon solar cells are the most economical ones to produce affordable energy. In this paper, a systematic study was done on the diffusion of phosphorous in multi-crystalline silicon during solar cell emitter formation. All parameters involved in the conversion of a multi-crystalline p-type silicon to a p-n junction were analyzed quantitatively. This systematic approach predicts the effect of inputs on the outputs which decreases the number of the trail runs. The analysis result indicate, that raising the diffusion temperature from 830 to 880 A degrees C decreases the sheet resistance by -100 Omega/sq, and increasing POCl3 flow from 300 to 500 SCCM has an effect of -21 Omega/sq.
|
|
| 40. |
- Kwiatkowski, Adam, et al.
(författare)
-
Structural and magnetic properties of MnAs/GaAs ferromagnetic semiconductor nanocomposite material
- 2008
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 19:8-9, s. 740-743
-
Tidskriftsartikel (refereegranskat)abstract
- Self-organized (Ga,Mn)As nanoclusters, embedded in GaAs and formed during thermal annealing of Ga1-xMnxAs layer at 500 degrees C or 600 degrees C, were studied using Transmission Electron Microscopy (TEM) and Magnetic Force Microscopy (MFM). We found that 10-20 nm large NiAs-type hexagonal MnAs nanocrystals gave magnetic contrast in MFM images, whereas smaller zinc-blende nanoinclusions were not visible by means of this technique. Theoretical simulations showed that MFM contrasts reflect interaction between magnetic tip and many randomly distributed MnAs nanocrystals.
|
|
| 41. |
- Lankinen, A., et al.
(författare)
-
Dislocations at the interface between sapphire and GaN
- 2008
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 19:2, s. 143-148
-
Tidskriftsartikel (refereegranskat)abstract
- GaN layers grown by metal organic vapour phase epitaxy on sapphire were imaged by synchrotron radiation X-ray topography. The threading dislocations could not be resolved in the topographs due to their high density, but a smaller density of about 10(5) cm(-2) defects were seen in the interface between GaN and sapphire by utilizing large-area back-reflection topography for the sapphire substrates. The misfit dislocation images in the topographs form a well-resolved cellular network, in which the average cell size is roughly 30 mu m. Different cell shapes in the misfit dislocation networks are observed on different samples. Also, images of small-angle grains of similar size were found in transmission section topographs of the GaN layers.
|
|
| 42. |
- Li, J., et al.
(författare)
-
Study of selective isotropic etching Si1−xGex in process of nanowire transistors
- 2020
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 31:1, s. 134-143
-
Tidskriftsartikel (refereegranskat)abstract
- On approach towards the end of technology roadmap, a revolutionary approach towards the nanowire transistors is favorable due to the full control of carrier transport. The transistor design moves toward vertically or laterally stacked Gate-All-Around (GAA) where Si or SiGe can be used as channel material. This study presents a novel isotropic inductively coupled plasma (ICP) dry etching of Si1−xGex (0.10 ≤ x ≤ 0.28) in SiGe/Si multilayer structures (MLSs) with high selectivity to Si, SiO2, Si3N4 and SiON which can be applied in advanced 3D transistors and Micro-Electro-Mechanical System (MEMS) in future. The profile of SiGe etching for different thicknesses, compositions and locations in MLSs using dry or wet etch have been studied. A special care has been spent for layer quality of Si, strain relaxation of SiGe layers as well as residual contamination during the etching. In difference with dry etching methods (downstream remote plasma), the conventional ICP source in situ is used where CF4/O2/He gas mixture was used as the etching gas to obtain higher selectivity. Based on the reliability of ICP technique a range of etching rate 25–50 nm/min can be obtained for accurate isotropic etching of Si1−xGex, to form cavity in advanced 3D transistor processes in future.
|
|
| 43. |
- Li, Zhicheng, et al.
(författare)
-
Influence of AST additives on the stability of PTCR characteristics and microstructure in ferroelectric ceramics
- 2004
-
Ingår i: Journal of materials science. Materials in electronics. - 0957-4522 .- 1573-482X. ; 15:8, s. 561-567
-
Tidskriftsartikel (refereegranskat)abstract
- (Ba0.69Pb0.31)TiO3 ceramics were prepared using Al2O3, SiO2, additives and excess of TiO2 (AST). The characteristics of positive temperature coefficient of resistivity (PTCR) was studied and the corresponding microstructures were investigated using atomic force microscopy and scanning electron microscopy. The results showed that the PTCR effect was related to the AST additives. The maximum value of resistivity in the ceramics with lower content of or without Al2O3 and SiO2 additives was much lower than in those with AST additives. Ceramics with low AST content, which were heated by electric field to a temperature much higher than their Curie temperature, lost the PTCR effect after the electric field stimulation. The microstructure observations revealed that re-crystallization took place in the ceramics with lower content of or without AST additives resulting in the loss of the PTCR effect.
|
|
| 44. |
- Li, Zhicheng, et al.
(författare)
-
Microstructure and PTCR effect of La-doped BaPbO3 ceramics
- 2004
-
Ingår i: Journal of materials science. Materials in electronics. - 0957-4522 .- 1573-482X. ; 15:3, s. 183-186
-
Tidskriftsartikel (refereegranskat)abstract
- La-doped BaPbO3 ceramics were prepared by using BaCO3 and PbO. Electrical properties and microstructure of the ceramics were studied. The results show a thin surface layer with a very low resistivity, and the interior of the ceramics with the characteristics of positive temperature coefficient of resistivity (PTCR). The PTCR behavior was related to the La content. The investigation by scanning electron microscopy and transmission electron microscopy revealed that the low resistivity of the surface layer was due to formation of a nano-size BaPbO3 phase with metallic properties.
|
|
| 45. |
- Liu, Jinbiao, et al.
(författare)
-
Study of n-type doping in germanium by temperature based PF+ implantation
- 2020
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 31, s. 161-166
-
Tidskriftsartikel (refereegranskat)abstract
- Incorporation of P in germanium was studied by using PF+ molecular implantation in a range from room temperature to 400 °C. The presence of F acted as a barrier for P in-diffusion and resulted in higher activation of P at room temperature. In addition, it is found that when the implantation is performed at 400 °C, the residual defects are stable and the diffusion of P can be blocked during activation annealing. Therefore, the final junction depth could be well controlled by the implantation process itself. This method is meaningful for the shallow junction formation in sub 14-nm Ge-based FinFETs or high-performance photodetectors.
|
|
| 46. |
- Luo, Xin, 1983, et al.
(författare)
-
Boron nitride nanofiber and indium composite based thermal interface materials for electronics heat dissipation applications
- 2014
-
Ingår i: Journal of Materials Science: Materials in Electronics. - 1573-482X .- 0957-4522. ; 25:5, s. 2333-2338
-
Tidskriftsartikel (refereegranskat)abstract
- With increased power density and continued miniaturization, effective thermal dissipation is of significant importance for operational lifetime and reliability of electronic system. Advanced thermal interface materials (TIMs) with excellent thermal performance need to be designed and developed. Here we report novel TIMs consisted of boron nitride (BN) nanofibers and pure indium (In) solder for heat dissipation applications. The BN nanofibers are fabricated by electrospinning process and nitridation treatment. After surface metallization by sputtering, the porous BN film is infiltrated with liquid indium by squeeze casting to form the final solid composites. The new composites show the in-plane and through-plane thermal conductivity respectively of 60 and 20 W/m K. The direction dependence thermal properties of the TIM are due to the anisotropic thermal performance of BN nanofibers in the composite. A low thermal contact resistance of 0.2 K mm2/W is also achieved at the interface between this new composite and copper substrate. These competent thermal properties demonstrate the great potential of the BN–In TIMs in thermal management for electronic system.
|
|
| 47. |
- Luo, Xin, 1983, et al.
(författare)
-
Novel thermal interface materials: boron nitride nanofiber and indium composites for electronics heat dissipation applications
- 2014
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 25:5, s. 2333-2338
-
Tidskriftsartikel (refereegranskat)abstract
- With increased power density and continued miniaturization, effective thermal dissipation is of significant importance for operational lifetime and reliability of electronic system. Advanced thermal interface materials (TIMs) with excellent thermal performance need to be designed and developed. Here we report novel TIMs consisted of boron nitride (BN) nanofibers and pure indium (In) solder for heat dissipation applications. The BN nanofibers are fabricated by electrospinning process and nitridation treatment. After surface metallization by sputtering, the porous BN film is infiltrated with liquid indium by squeeze casting to form the final solid composites. The new composites show the in-plane and through-plane thermal conductivity respectively of 60 and 20 W/m K. The direction dependence thermal properties of the TIM are due to the anisotropic thermal performance of BN nanofibers in the composite. A low thermal contact resistance of 0.2 K mm(2)/W is also achieved at the interface between this new composite and copper substrate. These competent thermal properties demonstrate the great potential of the BN-In TIMs in thermal management for electronic system.
|
|
| 48. |
- Mahar, Ihsan Ali, et al.
(författare)
-
Glucose sensing via green synthesis of NiO-SiO2 composites with citrus lemon peel extract
- 2024
-
Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 35:7
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, NiO-SiO2-based composites were synthesized through low-temperature aqueous chemical growth utilizing a facile, low-cost, and environmentally friendly approach. The composite systems were prepared using a combination of silica gel and citrus lemon peel extract. Due to the remarkable green chemicals in orange peel extract, porous nanostructures have been developed with thin sheet-like properties. The composite materials were examined in terms of their crystalline structure, morphology, optical band gap, and surface chemical composition. An advanced non-enzymatic glucose sensor developed from NiO-SiO2 composites exhibits rich surface oxygen vacancies and abundant catalytic sites. Based on sample 2, cyclic voltammetry revealed a linear glucose concentration range between 0.1 and 20 mM, chronoamperometry exhibited glucose concentration ranges between 0.1 and 14 mM, and linear sweep voltammetry revealed glucose concentration ranges from 0.1 to 10 mM. In enzymatic glucose sensors, the minimum level of detection was estimated to be 0.08 mM. A number of sensor characterization parameters were examined, including selectivity, stability, reproducibility, and real-time applications. In addition, electrochemical impedance spectroscopy (EIS) has shown that the NiO-SiO2 composite performs well in non-enzymatic glucose sensing due to its low charge transfer resistance and high electrochemical active surface area (ECSA). NiO-SiO2 composites could have significant biomedical, energy conversion, and storage applications based on the results obtained.
|
|
| 49. |
- Manika, Georgia, 1986, et al.
(författare)
-
Development, dielectric response and functionality of SrTiO3/epoxy nanocomposites
- 2020
-
Ingår i: Journal of Materials Science: Materials in Electronics. - : Springer Science and Business Media LLC. - 1573-482X .- 0957-4522. ; 30, s. 13740-13748
-
Tidskriftsartikel (refereegranskat)abstract
- Composite systems of epoxy resin and SrTiO3 nanoparticles have been prepared and studied in different filler concentrations. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed that there was a successful filler integration and fine dispersion in the polymer matrix. Moreover, Broadband dielectric spectroscopy (BDS) was employed for the determination of the dielectric response of all manufactured systems. Dielectric results divulge three relaxation processes which are referred to: (a) glass to rubber transition of the polymer matrix (α-mode), (b) re-arrangement of polar side groups of the polymer matrix (β-mode) and (c) interfacial polarization between systems’ components. It was found that all nanodielectric systems exhibit enhanced dielectric properties which are mainly attributed to the semiconductive nanoinclusions and to the extended interface between the polymer matrix and the nanofiller. Finally, dynamic analysis of the relaxation processes was also performed. Vogel–Fulcher–Tammann equation describes the α-mode’s loss peak dependence on temperature, whereas the β-mode follows the Arrhenius expression. In case of β-mode it was found that the presence of the nanoinclusions hinders the orientation of the matrix’s polar side groups.
|
|
| 50. |
- Matindoust, Samaneh, et al.
(författare)
-
Ammonia gas sensor based on flexible polyaniline films for rapid detection of spoilage in protein-rich foods
- 2017
-
Ingår i: Journal of materials science. Materials in electronics. - : Springer-Verlag New York. - 0957-4522 .- 1573-482X. ; 28:11, s. 7760-7768
-
Tidskriftsartikel (refereegranskat)abstract
- This work details the fabrication and performance of a sensor for ammonia gas, based on conducting polymer. The fabrication procedure consists following steps; polyaniline synthesis via oxidative polymerization technique, then a sensitive polyaniline film was deposited on a printed circuit board and finally, polyaniline microdevice were assembled on an interdigitated electrode arrays to fabricate the sensor for amomonia gas detection. Response time of this chemiresistive devices and humidity impact were examined for NH3 sensitivity and compared with commercial gas sensors (Taguchi Model 826). Data export from sensor to the computer was carried out via data logger model ADC-24 and analyzed using SPSS software. The sensor was found to have a rapid (t = 40 s) and stable linear response to ammonia gas in the concentration range of interest (50-150 ppm) under room temperature operation condition. It was reviled also reliable results to the variation of environment humidity. Power consumption, sensitivity, dimension, flexibility and fabrication cost were used as most important parameters to compare the new polymer based device with those of other similar works and the results showed that small size, low cost, flexibility, low power consumption and high sensitivity are from the benefits of this innovative device. In real-time application conditions flexible polyaniline based gas sensor with polyimide substrate in thickness 0.25 mm exhibits relatively good performance and accurate evaluation of food spoilage.
|
|
