SwePub - sökning: L773:0042 207X

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1.	Ali, Sharafat, et al. (författare) Novel transparent Mg-Si-O-N thin films with high hardness and refractive index 2016 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 131, s. 1-4 Tidskriftsartikel (refereegranskat)abstract There is an increasing demand for glass materials with better mechanical and optical properties for display and electronic applications. This paper describes the deposition of novel thin films of Mg-Si-O-N onto float glass substrates. Amorphous thin films in the Mg-Si-O-N system with high nitrogen and magnesium contents were deposited by reactive RF magnetron co-sputtering from Mg and Si targets in Ar/N2/O2 gas mixtures. The thin films studied span an unprecedented range of compositions up to 45 at% Mg and 80 at% N out of cations and anions respectively. Thin films in the Mg-Si-O-N system were found to be homogeneous and transparent in the visible region. Mechanical properties like hardness (H) and reduced elastic modulus (Er) show high values, up to 21 GPa and 166 GPa respectively. The refractive index (1.87-2.00) increases with increasing magnesium and nitrogen contents.
2.	Barankova, Hana, et al. (författare) Reactive Deposition of TiN Films by Magnetron with Magnetized Hollow Cathode Enhanced Target 2018 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 152, s. 123-127 Tidskriftsartikel (refereegranskat)abstract Magnetized Hollow Cathode Activated Magnetron in which the target is coupled with the hollow cathode magnetized by the magnetic field of the magnetron was tested in the reactive process of TiN deposition. Increased deposition rate compared to the Ti metal deposition rate was confirmed. The depositions as well as optical measurements were performed at several pressures in the reactor. The results of the TiN reactive deposition are presented and discussed, including the TiN deposition in pure nitrogen.
3.	Beshkova, M., et al. (författare) Device applications of epitaxial graphene on silicon carbide 2016 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 128, s. 186-197 Forskningsöversikt (refereegranskat)abstract Graphene has become an extremely hot topic due to its intriguing material properties allowing for ground-breaking fundamental research and applications. It is one of the fastest developing materials during the last several years. This progress is also driven by the diversity of fabrication methods for graphene of different specific properties, size, quantity and cost. Graphene grown on SiC is of particular interest due to the possibility to avoid transferring of free standing graphene to a desired substrate while having a large area SiC (semi-insulating or conducting) substrate ready for device processing. Here, we present a review of the major current explorations of graphene on SiC in electronic devices, such as field effect transistors (FET), radio frequency (RF) transistors, integrated circuits (IC), and sensors. The successful role of graphene in the metrology sector is also addressed. Typical examples of graphene on SiC implementations are illustrated and the drawbacks and promises are critically analyzed. (C) 2016 Elsevier Ltd. All rights reserved.
4.	Chi, Chaodan, et al. (författare) Molecular beam epitaxy growth of GaSb1-xBix without rotation 2019 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X. ; 168 Tidskriftsartikel (refereegranskat)abstract GaSb1-xBix thin film was grown on a 2 inch GaSb substrate by molecular beam epitaxy (MBE) without substrate rotation. Bi composition is found to vary from 2.76% to 3.98% across the wafer. The distribution of Bi content is mainly determined by spatial non-uniformity of Sb/Ga flux ratio, while Bi flux has slightly influence. Ostwald ripening process is confirmed to be reason for bigger Bi droplets via Bi surface diffusion. With the increase of Sb/Ga flux ratio, Ostwald ripening process is suppressed. At high Bi flux, excess Ga atoms accumulate on surface and form droplets.
5.	Elhag, Sami, et al. (författare) Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis 2015 Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 116, s. 21-26 Tidskriftsartikel (refereegranskat)abstract Generally, the anisotropic shape of inorganic nano-crystal can be influenced by one or more of different parameters i.e. kinetic energy barrier, temperature, time, and the nature of the capping molecules. Here, different surfactants acting as capping molecules were used to assist the aqueous chemical growth of zinc oxide (ZnO) nanostructures on Au coated glass substrates. The morphology, crystal quality and the photoluminescence (PL) properties of the ZnO nanostructures were investigated. The PL properties of the prepared ZnO nanostructures at room temperature showed a dominant UV luminescence peak, while the "green yellow" emissions were essentially suppressed. Moreover, the ZnO nanostructures were investigated for the development of a glucose biosensor. An adsorbed molecule has direct contribution on the glucose oxidase/ZnO/Au sensing properties. We show that the performance of a ZnO-based biosensor can be improved by tailoring the properties of the ZnO biomolecule interface through engineering of the morphology, effective surface area, and adsorption capability.
6.	Fondell, Mattis, et al. (författare) Phase control of iron oxides grown in nano-scale structures on FTO and Si(100) : Hematite, maghemite and magnetite 2015 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 117, s. 85-90 Tidskriftsartikel (refereegranskat)abstract We demonstrate that iron oxide in the form of hematite, suitable as absorption material in photo-electrochemical cells, can be produced by pulsed chemical vapour deposition. By choosing carbon monoxide or nitrogen as carrier gases in the process the phase and granularity of the grown material can be controlled. The choice of carrier gas affect the decomposition rate of iron pentacarbonyl used as iron precursor. The iron oxide phase is also dependent on the chosen substrate, here fluorine doped tin oxide and crystalline silicon have been used. Regardless of the substrate nitrogen yields hematite, whereas carbon monoxide gives, magnetite on Si and maghemite on fluorine doped tin oxide. A combination of Raman spectroscopy, X-ray diffraction, and hard X-ray photoelectron spectroscopy were used for characterization of the crystalline phase and chemical composition in the films. Scanning electron microscopy were used to visualise the deposited films' nano-structure.
7.	Greczynski, Grzegorz, et al. (författare) Peak amplitude of target current determines deposition rate loss during high power pulsed magnetron sputtering 2016 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 124 Tidskriftsartikel (refereegranskat)abstract Film growth rates during DCMS and HIPIMS sputtering in Ar are measured for ten technologically relevant elemental target materials: Al, Si, Ti, Cr, Y, Zr, Nb, Hf, Ta, and W, spanning wide range of masses, ionization energies, and sputter yields. Surprisingly, the ratio of power-normalized HIPIMS and DCMS rates a decays exponentially with increasing peak target current density J(T)(max) for all metals. The effect of J(T)(max) on alpha is dramatic: alpha approximate to 1 in the limit of lowest J(T)(max) values tested (0.04 A/cm(2)) and decreases to only 0.12 with J(T)(max) similar to 3 A/cm(2). With the exception of Al and Si, alpha(J(T)(max)) curves overlap indicating that the debated rate loss in HIPIMS is to large extent determined by the peak amplitude of the HIPIMS target current for all tested metals. Back attraction of ionized target species is responsible for such large variation in a. (C) 2015 Elsevier Ltd. All rights reserved.
8.	Greczynski, Grzegorz, 1973-, et al. (författare) Strategy for tuning the average charge state of metal ions incident at the growing film during HIPIMS deposition 2015 Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 116, s. 36-41 Tidskriftsartikel (refereegranskat)abstract Energy and time-dependent mass spectrometry is used to determine the relative number density of singly- and multiply-charged metal-ion fluxes incident at the substrate during high-power pulsed magnetron sputtering (HIPIMS) as a function of the average noble-gas ionization potential. Ti is selected as the sputtering target since the microstructure, phase composition, properties, and stress-state of Ti-based ceramic thin films grown by HIPIMS are known to be strongly dependent on the charge state of Tin+ (n = 1, 2, …) ions incident at the film growth surface. We find that the flux of Tin+ with n > 2 is insignificant; thus, we measure the Ti2+/Ti+ integrated flux ratio JTi2+ =JTi+ at the substrate position as a function of the choice of noble gase Ne, Ar, Kr, Xe, as well as Ne/Ar, Kr/Ar, and Xe/Ar mixtures – supporting the plasma. We demonstrate that by changing noble-gas mixtures, JTi2+ varies by more than two orders of magnitude with only a small change in JTi+ . This allows the ratio JTi2+ =JTi+ to be continuously tuned from less than 0.01 with Xe, which has a low first-ionization potential IP1, to 0.62 with Ne which has a high IP1. The value for Xe, IP1Xe= 12.16 eV, is larger than the first ionization potential of Ti, IP1Ti= 6.85 eV, but less than the second Ti ionization potential, IP2Ti= 13.62 eV. For Ne, however, IP1Ne= 21.63 eV is greater than both IP1Ti and IP2Ti. Therefore, the high-energy tail of the plasma-electron energy distribution can be systematically adjusted, allowing JTi2+/JTi+ to be controllably varied over a very wide range.
9.	Hellgren, Niklas, et al. (författare) High-power impulse magnetron sputter deposition of TiBx thin films : Effects of pressure and growth temperature 2019 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 169 Tidskriftsartikel (refereegranskat)abstract Titanium boride, TiBx thin films are grown in pure Ar discharges by high-power impulse magnetron sputtering (HiPIMS) from a compound TiB2 target Film compositions are determined by time-of-flight elastic recoil detection analysis and Rutherford backscattering spectrometry as a function of deposition temperature (T-s = 25-900 degrees C) and Ar pressure (p(Ar) = 0.67-2.67 Pa, 5-20 mTorr). For reference, films are also grown by direct current magnetron sputtering (dcMS) under similar conditions. The HiPIMS waveform, average target power P-T, and resulting film compositions are strongly dependent not only on P-Ar, but also on T-s. At high pressures the effect of varying T-s on P-T is minimal, while at lower P-Ar the effect of T-s is more pronounced, due to substrate-temperature-induced gas rarefaction. Films grown by HiPIMS at 0.67 Pa are understoichiometric, with B/Ti = 1.4-1.5, while at 2.67 Pa, B/Ti decreases from 2.4 to 1.4 as T-s increases from 25 to 900 degrees C. dcMS-deposited films are overstoichiometric (B/Ti similar or equal to 3) when grown at low pressures, and near-stoichiometric (B/Ti similar or equal to r 1.9-2.2) for higher P-Ar. All experimental results are explained by differences in the ionization potentials of sputtered Ti and B atoms, together with P-Ar- and T-s-dependent gas-phase scattering.
10.	Hsiao, Ching-Lien, et al. (författare) Nucleation and core-shell formation mechanism of self-induced InxAl1−xN core-shell nanorods grown on sapphire substrates by magnetron sputter epitaxy 2016 Ingår i: Vacuum. - : Pergamon Press. - 0042-207X .- 1879-2715. ; 131, s. 39-43 Tidskriftsartikel (refereegranskat)abstract Nucleation of self-induced nanorod and core-shell structure formation by surface-induced phase separation have been studied at the initial growth stage. The growth of well-separated core shell nanorods is only found in a transition temperature region (600 degrees C amp;lt;= T amp;lt;= 800 degrees C) in contrast to the result of thin film growth outside this region (T amp;lt; 600 degrees C or T amp;gt; 800 degrees C). Formation of multiple compositional domains, due to phase separation, after similar to 20 nm InxAl1-xN epilayer growth from sapphire substrate promotes the core-shell nanorod growth, showing a modified Stranski-Krastanov growth mode. The use of VN seed layer makes the initial growth of the nanorods directly at the substrate interface, revealing a Volmer-Weber growth mode. Different compositional domains are found on VN template surface to support that the phase separation takes place at the initial nucleation process and forms by a self-patterning effect. The nanorods were grown from In-rich domains and initiated the formation of core-shell nanorods due to spinodal decomposition of the InxAl1-xN alloy with a composition in the miscibility gap.
11.	Karlsson, Linda, et al. (författare) Graphene on graphene formation from PMMA residues during annealing 2017 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 137, s. 191-194 Tidskriftsartikel (refereegranskat)abstract PMMA is a common support material for transferring graphene between substrates. However, PMMA residues typically remain on the graphene sheet after the transfer process. A high temperature annealing process is commonly applied to reduce the amount of PMMA residues. It is also known that high temperature annealing of PMMA causes the PMMA to graphitize, which has been used as a method to synthesize graphene on metal substrates. In this letter we show the development of additional graphene layers during high temperature annealing, which occurs on a single, clean, graphene sheet. The additional graphene is nucleated from the decomposition products of PMMA residues. (C) 2017 Elsevier Ltd. All rights reserved.
12.	Khomyak, V., et al. (författare) Band-gap engineering of ZnO1-xSx films grown by rf magnetron sputtering of ZnS target 2015 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 121, s. 120-124 Tidskriftsartikel (refereegranskat)abstract Structural and optical properties of ZnO1-xSx (0 less than= x less than= 1.0) thin films grown onto sapphire substrates (c-Al2O3) at 300 degrees C by radio frequency (rf) magnetron sputtering of ZnS ceramic target are studied. A possibility of purposeful controlling sulfur content and, as consequence, ZnO1-xSx band gap energy via changing the ratio of the partial pressures of argon and oxygen are revealed. Linear dependence of ZnO lattice parameter c on S content suggests that structural properties of single-phase ternary alloys in the composition range between ZnO and ZnS obey Vegards law. The mechanisms of influence of gas mixing ratio on film growth and band gap energy are discussed. Cu(In,Ga)Se-2 (CIGS)-based heterojunction solar cells with ZnO1-xSx buffer layers were fabricated by one-cycle magnetron sputtering procedure. Electrical characteristics of Cd-free devices are comparable to those of CdS-containing photovoltaic heterostructures, thereby indicating prospects of using ZnO1-xSx layers for fabrication of CIGS solar cells. (C) 2015 Elsevier Ltd. All rights reserved.
13.	Liang, Jiamin, et al. (författare) Synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates with Al-C/Si interlayers as diffusion barriers 2019 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 160, s. 128-132 Tidskriftsartikel (refereegranskat)abstract Zr2Al3C4 coatings are potential candidates to prevent claddings of traditional Zr-based alloys from severe oxidation in water steam at high temperature. However, the diffusion of aluminum between coating and substrates at high temperature results in a coating composition deviating from the compositional domain for formation of the Zr2Al3C4 phase. Thus, synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates is challenging. Here, we report that the Zr2Al3C4 phase can be obtained on zirconium alloy (ZIRLO) substrates where an Al-C/Si interlayer deposited by magnetron sputtering is introduced. The Al-C/Si interlayer prevented elemental diffusion of aluminum between the Zr-Al-C coating and the substrates during a post-annealing process at 800 degrees C for 3 h. The Al/Zr ratio of the Zr-Al-C coating after annealing was 0.96 and 0.59 in the cases of with and without Al-C/Si interlayer, respectively. Hence, the Al-C/Si interlayer acts as diffusion barrier and greatly decreases the deviation from the standard stoichiometric ratio of the Zr2Al3C4 phase, which facilitates the formation of the Zr2Al3C4 phase in the final coating.
14.	Liu, Yanan, et al. (författare) A novel fabrication strategy for highly porous FeAl/Al2O3 composite by thermal explosion in vacuum 2018 Ingår i: Vacuum. - : Elsevier. - 0042-207X. ; 149, s. 225-230 Tidskriftsartikel (refereegranskat)abstract The high porosity of FeAl/Al2O3 composites was successfully prepared via a low-energy consumption method of thermal explosion (TE) in vacuum from reactant mixtures of Fe, Al and Fe2O3. The temperature profiles, phase compositions, microstructure, porosity and pore size of the products were investigated. The TE reactions were ignited between 639 and 648 °C and maximum combustion temperatures reached to 1196–1867 °C. XRD patterns showed that FeAl, Fe2Al5 and Al2O3 were formed via TE reaction, and FeAl and Al2O3 were evolved as dominant phase after the final sintering at 1100 °C. The FeAl/Al2O3 composites exhibited an interconnected pore structure with porosities and pore size of 52–61% and 27–32 μm, respectively.
15.	Ma, D. L., et al. (författare) Optimal target sputtering mode for aluminum nitride thin film deposition by high power pulsed magnetron sputtering 2019 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 160, s. 410-417 Tidskriftsartikel (refereegranskat)abstract Low surface roughness, low residual stress, and(002) textured aluminum nitride(AlN) thin films are favored for applications in microelectronic and optoelectronic devices. In this paper, AlN thin films were deposited by reactive high power pulsed magnetron sputtering(HPPMS). The effect of aluminum target sputtering mode and sputtering power on thin film residual stress, crystalline structure, surface roughness, and morphology of AlN thin films was studied. The results indicate that, with Al target sputtering mode transfer from metallic mode to transitional and compound modes, respectively, the number of Al species decrease, and ion-to-neutral ratio of Al species increase. Comparing the AIN thin film deposited in compound mode with that deposited in transitional mode, the latter exhibited lower surface roughness and residual stress. In addition, AlN thin film with (002) texture and lower residual stress is obtained by increasing sputtering power in transitional mode. For fabricating AIN film via reactive HPPMS with a particular (002) texture, low surface roughness, and residual stress, sputtering the target in the transitional mode with high sputtering power is optimal.
16.	Mehta, Manan, et al. (författare) Synthesis of MoS2-TiO2 nanocomposite for enhanced photocatalytic and photoelectrochemical performance under visible light irradiation 2018 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X. ; 155, s. 675-681 Tidskriftsartikel (refereegranskat)abstract In this work, we have prepared MoS2 nanoflakes modified TiO2 nanoparticles (MoS2-TiO2 nanocomposite) with varying concentration of MoS2 (2.5–10 wt.%) by a two-step hydrothermal synthesis method involving specific preparation conditions for the TiO2 nanoparticles and MoS2 nanoflakes. The prepared samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS) techniques. The photocatalytic activity of the pristine TiO2 nanoparticles and MoS2-TiO2 nanocomposite samples were evaluated by examining the photocatalytic degradation of Rhodamine B (RhB). The photoelectrochemical activity of these samples were measured by performing solar water splitting experiments under visible light irradiation. It was observed that the MoS2-TiO2 nanocomposite with 7.5 wt.% MoS2 exhibits highest photocatalytic and photoelectrochemical activity as it has the optimum amount of MoS2 nanoflakes which probably minimizes the recombination of photogenerated charge carriers as compared to other concentrations of MoS2 in MoS2-TiO2 nanocomposite and pristine TiO2 nanoparticles. In addition, a rather high photocatalytic reaction rate constant was observed for MoS2-TiO2 nanocomposite with 7.5 wt.% MoS2 nanoflakes.
17.	Mikhlin, Yuri, et al. (författare) Interaction of sphalerite with potassium n-butyl xanthate and copper sulfate solutions studied by XPS of fast-frozen samples and zeta-potential measurement 2016 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 125, s. 98-105 Tidskriftsartikel (refereegranskat)abstract We acquired low-temperature X-ray photoelectron spectra of fast-frozen wet pastes prepared by centrifugation of the natural sphalerite slurries containing potassium n-butyl xanthate (KBX), without washing or any additional treatment, before and after the mineral activation in 0.1 mM CuSO4 solution. Zeta potentials of the slurry particles were also measured. The method allowed characterizing the mineral surfaces and adsorbates, volatile substances and hydrated species within the interfacial layers under more realistic flotation-related conditions. The uptake of xanthate by unactivated mineral was low even in 10 mM KBX, while the surface became metal-deficient (enriched in sulfur), more hydrophobic and contaminated with carbonaceous matter. Dibutyl dixanthogen was the major interfacial product of the interaction of Cu-activated sphalerite having the surface atomic Zn/Cu ratio of 3 and excess of sulfur with the KBX solutions. The spectra revealed only minor quantities of Zn and Cu xanthates and oxyhydroxides at all the samples; some hydrated K+ counter-ions were detected at the negatively charged surfaces after the xanthate treatment. The dixanthogen was concluded to form via oxidation of xanthate at the interface, probably catalyzed by surface cuprous species but not direct interaction with cupric ions.
18.	Mishra, Y. K., et al. (författare) Progress in electronics and photonics with nanomaterials 2017 Ingår i: Vacuum. - : Elsevier Ltd. - 0042-207X .- 1879-2715. ; 146, s. 304-307 Tidskriftsartikel (refereegranskat)abstract Nanomaterials have been at the center of attraction for almost five decades as their contributions to different disciplines such as electronics, photonics and medicine are enormous. Various kinds of nanomaterials have been developed and are currently utilized in innumerable applications. Nevertheless, their simple realization and easy and efficient upscaling are topics under intense investigation. Innovative strategies have been adopted for nanomaterial synthesis and their usability. Here, we provide a brief overview on nanomaterials ranging from basic understanding of their structure-property relationship to advanced applications. This editorial covers various aspects about nanomaterials, which will be useful/attractive for beginners in the field of nanotechnology as well as for experts and for industrialists looking forward to exploit them for real world applications.
19.	Music, Denis, et al. (författare) Electrical resistivity modulation of thermoelectric iron based nanocomposites 2018 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 157, s. 384-390 Tidskriftsartikel (refereegranskat)abstract Iron oxides are promising thermoelectrics, but their high electrical resistivity impedes broader applications. In this work, we have studied Fe oxides with metallic contributions. Pt and Ir additions are also considered to enhance the valence electron concentration and further modify the transport properties. Based on density functional theory explorations, Fe based clusters (Fe-3, Fe-4, and Fe3Pt) are suggested to act as nucleation sites for metallic crystallites, while O leads to formation of an amorphous matrix. This has been validated by transmission electron microscopy and x-ray photoelectron spectroscopy of sputter-grown Fe-Pt-Ir-O thin films. Densely packed bcc Fe grains, approx. 2-3 nm in diameter, are embedded in an amorphous Fe-O matrix in the as-grown state. The Seebeck coefficient reaches even -411 mu V K-1 and the electrical resistivity is up to 5 orders of magnitude lower than that of previously reported literature data on Fe oxides. We suggest that this peculiarity of our films is due to finite states localized at the Fermi level in these nanocomposites.
20.	Ning, Yuping, et al. (författare) Effects of substrates, film thickness and temperature on thermal emittance of Mo/substrate deposited by magnetron sputtering 2016 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 128, s. 73-79 Tidskriftsartikel (refereegranskat)abstract The thermal emittance of the Mo film, as an IR-refiector in solar selective absorbing coatings, is the most important property. The effects of the substrate material, the substrate surface roughness, the film thickness and the temperature on the thermal emittance of the Mo/substrate have been investigated. A series of Mo films with increasing film thickness were deposited on two types of substrate materials (glass and stainless steel). A saturated Mo thickness of 50 nm is found to produce the lowest thermal emittance. The thermal emittance of the Mo film is reduced by decreasing the substrate surface roughness. The emittance of the optimal Mo film remains 0.05 from 25 degrees C to 400 degrees C, which can meet the optical requirements for the IR-reflector.
21.	Ruess, H., et al. (författare) HPPMS deposition from composite targets : Effect of two orders of magnitude target power density changes on the composition of sputtered Cr-Al-C thin films 2017 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 145, s. 285-289 Tidskriftsartikel (refereegranskat)abstract The effect of target power density, substrate bias potential and substrate temperature on the thin film composition was studied. A Cr-Al-C composite target was sputtered utilizing direct current (DCMS: 2.3 W/cm(2)) and high power pulsed magnetron sputtering (HPPMS: 373 W/cm(2)) generators. At floating potential, all Cr-Al-C thin films showed similar compositions, independently of the applied target power density. However, as substrate bias potential was increased to -400 V, aluminum deficiencies by a factor of up to 1.6 for DCMS and 4.1 for HPPMS were obtained. Based on the measured ion currents at the substrate, preferential re-sputtering of Al is suggested to cause the dramatic Al depletion. As the substrate temperature was increased to 560 degrees C, the Al concentration was reduced by a factor of up to 1.9 compared to the room temperature deposition. This additional reduction may be rationalized by thermally induced desorption being active in addition to re-sputtering.
22.	Shu, Rui, et al. (författare) One-step synthesis of polycrystalline V2AlC thin films on amorphous substrates by magnetron co-sputtering 2017 Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 146, s. 106-110 Tidskriftsartikel (refereegranskat)abstract We prepared V-Al-C films on glass and silicon (with native SiO2 layer) substrates using magnetron co-sputtering at 600 degrees C. The composition and microstructure of these films were characterized by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Polycrystalline V2AlC phase was obtained in the films with nearly stoichiometric composition. The microstructural evolution includes random nucleation at the film/substrate interface, competitive growth resulting in a (110) preferred orientation with increasing thickness. The mechanism for crystallization could be understood in terms of polymorphic crystallization. The results show that polycrystalline MAX-phase V2AlC could be directly synthesized on amorphous substrates. (C) 2017 Elsevier Ltd. All rights reserved.
23.	Ström, Petter, et al. (författare) Characterisation of surface layers formed on plasma-facing components in controlled fusion devices : Role of heavy ion elastic recoil detection 2015 Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 122, s. 260-267 Tidskriftsartikel (refereegranskat)abstract Wall components retrieved from the TEXTOR tokamak after tracer experiments with nitrogen-15 and molybdenum hexafluoride (MoF6) injection were studied to determine deposition patterns and, by this, to conclude on material migration. Toroidal limiter tiles made of carbon fibre composites and fine grain graphite were examined using time-of-flight heavy ion elastic recoil detection analysis. Molybdenum deposition patterns indicated migration based on erosion and prompt re-deposition. Nitrogen-15 was trapped together with the deposited molybdenum. Some information on the depth distribution of species in the top 400 nm layer of the limiters was obtained; however surface roughness of the samples strongly limited resolution. In the case of molybdenum, the largest concentration was found in the 100 nm outermost layer, whereas fluorine and nitrogen-15 displayed more irregular profiles. Other species, besides deuterium fuel and carbon-12, were also identified: boron-10 and boron-11 originating from boronisations, carbon-13 from earlier tracer experiments, nitrogen-14 from plasma edge cooling and metals eroded from the Inconel wall.
24.	Ström, Petter, et al. (författare) Surface oxide and roughness on test samples for the Ultra High Vacuum section of the Laser Heater for the European XFEL 2018 Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 149, s. 83-86 Tidskriftsartikel (refereegranskat)abstract The European X-ray Free Electron Laser has recently started with operation for users. An approximately 3 m long ultra high vacuum laser heater section is implemented to overcome possible electron bunch instabilities. We describe the process of determining the oxide layer thickness and surface roughness on test samples of the internal surface material in the laser heater vacuum chambers using elastic recoil detection analysis and optical surface profiling. The results are compared to specified values and show that surface roughness on the samples is larger than the requested maximum, with RMS deviations from a mean plane of up to 1.76 mu m for 0.60 x 0.45 square millimeter scans. The maximum oxide layer thickness is 5.5 nm on non-electropolished surfaces assuming cuprous oxide with density 6.0 g per cubic centimeter and 4.0 nm on electropolished surfaces.
25.	Yuan, Kang, et al. (författare) Hot Corrosion Behavior of HVOF-sprayed CoNiCrAlYSi Coatings in a Sulphate Environment 2015 Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 122:part A, s. 47-53 Tidskriftsartikel (refereegranskat)abstract HVOF-sprayed CoNiCrAlYSi coatings were tested at 900 °C in a hot corrosion environment containing sodium–potassium sulphates. The HVOF spraying caused the typical splat-on-splat structure. The results after the hot corrosion testing showed that the corrosion preferentially occurred at the coating surface and the splat boundaries. The oxidation along the splat boundaries can isolate the splat from the underlying coating matrix. In those isolated splats or coating parts, internal oxidation and nitridation of Al took place, following that the Al-depleted coating fragments were then oxidized to spinels. For those coatings which had a worse splat boundary quality (i.e. with higher porosity and intersplat oxides) or had a worse coating surface quality (i.e. with more small coating fragments therefore more interfaces), heavier corrosion attack was observed on those coatings due to the corrosion of the splats or the coating fragments. The results indicated that the as-sprayed coating quality including porosity and surface morphology was important for the hot-corrosion resistance of the coatings.

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