| 1. |
- Ali, Sk Imran, et al.
(författare)
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Zn3Sb4O6F6 : Hydrothermal synthesis, crystal structure and nonlinear optical properties
- 2017
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 256, s. 158-161
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Tidskriftsartikel (refereegranskat)abstract
- Zn3Sb4O6F6 has been synthesized hydrothermally at 230 degrees C. The crystal structure was determined from single crystal X-ray diffraction data. It crystallizes in the cubic non-centrosymmetric space group I-43m with the unit cell parameter a = 8.1291(4) angstrom and is isostructural with M3Sb4O6F6 (M = Co, Ni). The new compound is the first oxofluoride containing Zn2+ and a p-element cation with a stereochemically active lone pair. The crystal structure is made up by [ZnO2F4] octahedra forming a network via corner sharing at F-atoms and [SbO3] trigonal pyramids that form [Sb4O6] cages that connect via the O-atoms to the Zn-atoms. Powder second harmonic generation (SHG) measurements using 1064 nm radiation on Zn3Sb4O6F6 indicate an SHG intensity of approximately 40 x alpha-SiO2.
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| 2. |
- Ballikaya, S., et al.
(författare)
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Thermoelectric and thermal stability improvements in Nano-Cu 2 Se included Ag 2 Se
- 2019
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Ingår i: Journal of Solid State Chemistry. - : Academic Press. - 0022-4596 .- 1095-726X. ; 273, s. 122-127
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Tidskriftsartikel (refereegranskat)abstract
- Recently, silver chalcogenides have attracted great attention due to their potential application for room temperature power generation and local cooling. In this work, we report the thermoelectric properties and thermal stability of bulk Ag 2 Se with nano-Cu 2 Se inclusions ((Ag 2 Se) 1-x (Cu 2 Se) x where x = 0, 0.02 and 0.05). Ag 2 Se samples were prepared via melting, annealing and the nanocomposite was prepared by ball milling this material with required amount of nano-Cu 2 Se; finally, the samples were consolidated by spark plasma sintering. High temperature and low temperature transport properties were assessed by the measurements of the Seebeck coefficient, electrical conductivity, thermal conductivity, and Hall coefficient. The phase composition and microstructure were explored by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, while the thermal stability of samples was investigated via heating microscopy and heat capacity measurement. Room temperature PXRD and SEM indicated that two separate phases of Ag 2 Se and Cu 2 Se form in nano-Cu 2 Se included composites. Heating microscopy and the heat capacity measurement indicate that the thermal stability of Ag 2 Se is enhanced with increasing nano-Cu 2 Se inclusions. The sign of the Seebeck coefficient, in agreement with the Hall coefficient, shows that electrons are the dominant carriers in all samples. The electrical conductivity of the samples increases and the Seebeck coefficient decreases with increasing amount of the nano-Cu 2 Se inclusion, likely due to augmented carrier concentration. Despite the larger electrical conductivity, the thermal conductivity is suppressed with nano-Cu 2 Se inclusions. A high power factor and reduced thermal conductivity lead to a maximum ZT value of 0.45 at 875 K for (Ag 2 Se) 1-x (nano-Cu 2 Se) x sample where x is 0.05.
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| 3. |
- Cano, A., et al.
(författare)
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Intercalation of pyrazine in layered copper nitroprusside : synthesis, crystal structure and XPS study
- 2019
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Ingår i: Journal of Solid State Chemistry. - : Elsevier. - 0022-4596 .- 1095-726X. ; 273, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid inorganic–organic solids form an interesting family of functional materials, where their functionalities are determined by both, the inorganic and organic building blocks. This study reports the intercalation of pyrazine in 2D copper nitroprusside, the crystal structure of the resulting hybrid solid and explores the scope of cryogenic X-ray photoelectron spectroscopy (XPS) to shed light on its electronic structure. In this material, the pyrazine molecule appears coordinated to Cu atoms from neighboring layers, to form the columns in the resulting 3D porous framework. Its crystal structure was solved and refined from the corresponding XRD powder pattern. XPS data, recorded under cryogenic conditions, provided fine details on the electronic structure of this hybrid solid. The binding energy values for the ligand atoms and the involved metals show a definite correlation with the structural data and FT-IR spectra. When XPS spectra were recorded at room temperature, a significant sample decomposition was observed. Three possible mechanisms for the sample damage during the XPS experiment are considered. The hybrid material under study is representative of a wide series of nanoporous solids obtained by intercalation of organic pillars between 2D inorganic solids.
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| 4. |
- Cedervall, Johan, et al.
(författare)
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Low temperature magneto-structural transitions in Mn3Ni20P6
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Academic Press Inc.. - 0022-4596 .- 1095-726X. ; 237, s. 343-348
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Tidskriftsartikel (refereegranskat)abstract
- X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm3¯m (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 12) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.
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| 5. |
- Cedervall, Johan, et al.
(författare)
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Magnetostructural transition in Fe5SiB2 observed with neutron diffraction
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 235, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The crystal and magnetic structure of Fe5SiB2 has been studied by a combination of X-ray and neutron diffraction. Also, the magnetocrystalline anisotropy energy constant has been estimated from magnetisation measurements. High quality samples have been prepared using high temperature synthesis and subsequent heat treatment protocols. The crystal structure is tetragonal within the space group I4/mcm and the compound behaves ferromagnetically with a Curie temperature of 760 K. At 172 K a spin reorientation occurs in the compound and the magnetic moments go from aligning along the c-axis (high T) down to the ab-plane (low T). The magnetocrystalline anisotropy energy constant has been estimated to 0.3 MJ/m3 at 300 K.
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| 6. |
- Celania, Chris, et al.
(författare)
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Structures, properties, and potential applications of rare earth-noble metal tellurides
- 2019
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 274, s. 243-258
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Tidskriftsartikel (refereegranskat)abstract
- As many nations continue to develop and industrialize, the global energy demands are rising rapidly. With the threat of climate change disaster looming, the search for sustainable, green energy has become of higher priority. Thermoelectric materials add an important facet to the mosaic of future energy plans by allowing the scavenging of (low-quality waste) heat created through other processes and their transformation back into useful electrical energy. Thermoelectrics (similar to other green energy sources like solar cells) have struggled to reach high enough efficiencies to allow their cost-effective widespread implementation. Thus, the search for new thermoelectric materials has gained momentum. This review covers the growing family of rare earth metal (R: Sc, Y, and La-Lu)-noble metal (M: Cu, Ag, Au, Pd and Pt)-tellurides which are an interesting group of materials in the discussed context. Rare earth metal -noble metal tellurides constitute an increasing family of structures, numbering nearly forty unique structure types and including quaternary and quinary compounds. Structures include 1D channel structures, 2D layered slab structures, and complex 3D networks. R-M-Te compounds provide a wide variety of p-type semiconducting materials to choose from. The effectiveness of these structures as thermoelectric materials range in utility, with most showing maximum performance (figure of merit, zT - see below) values in the mid to high temperature ranges. To date, this culminates in the highest zT for this family with TbCuTe2, zT = 1.0 at 750 K, which still has potential for optimization. Albeit most observed compounds have been structurally quite well characterized, for many a thorough investigation of their physical properties, be it transport or magnetism is lacking. This work strives to combine, analyze, and at times untangle the variety of structures and properties reported across the breadth of research on this family.
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| 7. |
- Ek, Gustav, et al.
(författare)
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Hydrogen induced structure and property changes in Eu3Si4
- 2019
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 277, s. 37-45
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Tidskriftsartikel (refereegranskat)abstract
- Hydrides Eu3Si4H2-X were obtained by exposing the Zintl phase Eu3Si4 to a hydrogen atmosphere at a pressure of 30 bar and temperatures from 25 to 300 degrees C. Structural analysis using powder X-ray diffraction (PXRD) data suggested that hydrogenations in a temperature range 25-200 degrees C afford a uniform hydride phase with an orthorhombic structure (Immm, a approximate to 4.40 angstrom, b approximate to 3.97 angstrom, c approximate to 19.8 angstrom), whereas at 300 degrees C mixtures of two orthorhombic phases with c approximate to 19.86 and approximate to 19.58 angstrom were obtained. The assignment of a composition Eu3Si4H2+x is based on first principles DFT calculations, which indicated a distinct crystallographic site for H in the Eu3Si4 structure. In this position, H atoms are coordinated in a tetrahedral fashion by Eu atoms. The resulting hydride Eu3Si4H2 is stable by -0.46 eV/H atom with respect to Eu3Si4 and gaseous H-2. Deviations between the lattice parameters of the DFT optimized Eu3Si4H2 structure and the ones extracted from PXRD patterns pointed to the presence of additional H in interstitials also involving Si atoms. Subsequent DFT modeling of compositions Eu3Si4H3 and Eu3Si4H4 showed considerably better agreement to the experimental unit cell volumes. It was then concluded that the hydrides of Eu3Si4 have a composition Eu3Si4H2+x (x
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| 8. |
- Fang, Hailiang, et al.
(författare)
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Directly obtained tau-phase MnAl, a high performance magnetic material for permanent magnets
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 237, s. 300-306
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Tidskriftsartikel (refereegranskat)abstract
- The metastable tetragonal iota-phase has been directly obtained from casting Mn0.54Al0.46 and (Mn0.55Al0.45)(100)C-2 using the drop synthesis method. The as-casted samples were ball milled to decrease the particle size and relaxed at 500 degrees C for 1 h. The phase composition, crystallographic parameters, magnetic properties and microstructure were systematically studied. The results reveal that the iota-phase could be directly obtained from drop synthesis. The highest M-s of 117 emu/g was achieved in the (Mn0.55Al0.45)(100)C-2 where the iota-phase was stabilized by doping with carbon. Carbon doping increased the c/a ratio of the tau-phase as it occupies specific interstitial positions (1/2, 1/2, 0) in the structure. Furthermore, ball milling increases the coercivity (H-c) at the expense of a decrease in magnetic saturation (M-s). The increase in coercivity is explained by a decrease of grain size in conjunction with domain wall pinning due to defects introduced during the ball milling process.
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| 9. |
- Grau-Atienza, A., et al.
(författare)
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Magnetically separable mesoporous Fe3O4/silica catalysts with very low Fe3O4 content
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 237, s. 138-143
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Tidskriftsartikel (refereegranskat)abstract
- Two magnetically separable Fe3O4/SiO2 (aerogel and MSU-X) composites with very low Fe3O4 content (< 1 wt%) have been successfully prepared at room temperature by co-condensation of MPTES-functionalized Fe3O4 nanoparticles (NPs) with a silicon alkoxide. This procedure yields a homogeneous incorporation of the Fe3O4 NPs on silica supports, leading to magnetic composites that can be easily recovered using an external magnetic field, despite their very low Fe3O4 NPs content (ca. 1 wt%). These novel hybrid Fe3O4/SiO2 materials have been tested for the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide showing an enhancement of the stability of the NPs in the Fe3O4/silica aerogel as compared to the Fe3O4 NPs alone, even after five catalytic cycles, no leaching or agglomeration of the Fe3O4/SiO2 systems.
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| 10. |
- Haiduk, Y. S., et al.
(författare)
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Study of WO 3 –In 2 O 3 nanocomposites for highly sensitive CO and NO 2 gas sensors
- 2019
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Ingår i: Journal of Solid State Chemistry. - : Academic Press Inc.. - 0022-4596 .- 1095-726X. ; 273, s. 25-31
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Tidskriftsartikel (refereegranskat)abstract
- Pure semiconductor tungsten oxide (WO 3 ), indium oxide (In 2 O 3 ) and mixed nanocomposites with different WO 3 to In 2 O 3 ratios were successfully synthesized by simple sol-gel method following calcination at 600 °C. The morphology, phase composition and features of crustal structure of the materials were studied by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transition electron microscopy and electron paramagnetic resonance spectroscopy. It was found that the nanocomposite materials are characterized by fine crystallinity of 8–38 nm, highly defective crystal cells and presence of delocalized electrons in their structures, which can significantly affect gas sensitivity. The gas sensors based on WO 3 –In 2 O 3 composite structures exhibited excellent CO and NO 2 detecting performance at optimal operating temperature of ∼240 °C and ∼140 °C, respectively.
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