| 1. |
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| 2. |
- Mahmoudkhani, Amir Hussein, et al.
(författare)
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Layered strontium phenylphosphonate: synthesis, thermal properties and crystal structure from X-ray powder diffraction data
- 2002
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Ingår i: Solid State Sciences. - 1293-2558. ; 4:6, s. 873-878
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Tidskriftsartikel (refereegranskat)abstract
- Strontium phenylphosphonate, Sr(PhPO3H)2, was synthesized by the reaction of strontium carbonate and phenylphosphonic acid. The compound was structurally characterized by Rietveld refinement on X-ray powder diffraction data. It consists of a layered structure with inorganic framework of SrO8 polyhedra from which phenyl groups are pointing out. The compound is isomorphous with the already known calcium and barium phenylphosphonates. Infrared spectroscopy analysis shows the presence of (P-)O-H...O hydrogen bonds in the solid material. The thermal behavior of the compound in the range 30650°C, studied by thermogravimetry (TG), differential thermal analysis (DTA) and X-ray powder thermodiffractometry, revealed that strontium phenylphosphonate is stable up to 330°C. The compound undergoes consequent thermal decomposition and phase transitions above 330°C temperatures until it converts to crystalline Sr(PO3)2 above 570°C.
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| 3. |
- Flemström, A., et al.
(författare)
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Effects from hydrogen bonds on water structure in (H3O)2[Mo6Cl8X6]·yH2O X=Cl (y=7), Br (y=6), or I (y=6)
- 2002
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Ingår i: Solid State Sciences. - 1293-2558 .- 1873-3085. ; 4:8, s. 1017-1022
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Tidskriftsartikel (refereegranskat)abstract
- The compounds (a) (H3O)2[Mo6Cl8Cl6]·7H2O, (b) (H3O)2[Mo6Cl8Br6]·6H2O and (c) (H3O)2[Mo6Cl8I6]·6H2O were synthesized from MoCl2 and the corresponding halide acid. The structures were determined by X-ray diffraction and refined in the monoclinic space groups, (a) C2/c and for (b) and (c) P21/a. The cell parameters were for (a), a=17.3607(2), b=9.1351(7), c=18.6300(2) Å and β=98.13(1)°, (b) a=17.4295(2), b=9.3803(10), c=9.3769(12) Å and β=101.04(1)° and (c) a=18.0083(10), b=9.7612(10), c=9.8139(12) Å and β=100.20(2)°. The positions of the hydrogen atoms were determined by theoretical energy optimization. The structures are compared with respect to the effect of hydrogen bonding on the water structure.
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| 4. |
- Hannerz, H, et al.
(författare)
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Structure and magnetic susceptibility of MnNb3O6
- 1999
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Ingår i: Solid State Sciences. - 1293-2558 .- 1873-3085. ; 1, s. 567-575
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Tidskriftsartikel (refereegranskat)abstract
- The mixed valence state niobium compound MnNb3O6 was found while studying phase formations in the system MnO-Nb2O5-NbO. It is isostructural with AxNb3O6, x ≤ 1 and A = Na, Ca. Single crystals were obtained by heating MnC2O4 · 2H2O and Nb2O5 in a flow of H2 at 1300 °C. Monophasic samples were also prepared by heating stoichiometric mixtures of MnO, Nb2O5 and Nb in niobium ampoules under Ar(g) at 1100 °C. The crystal structure of MnNb3O6 (Immm, Z = 4, a = 7.1057(5), b = 10.1420(6), c = 6.5341(5) Å) was refined, using singlecrystal MoKα X-ray diffraction data, to a weighted R value of 0.018 for 329 unique reflections. The structure contains undulating layers of NbO6 octahedra of the type α2[NbO6/2]in the ac-plane, with the octahedra sharing edges along [001]and corners along [100]. Between the layers there are columns along [001]of edge-sharing square MnO8 prisms alternating with columns containing Nb2O8 clusters with an Nb-Nb distance of 2.6163(5) Å. The magnetic susceptibility shows a Curie-Weiss behaviour: χM = C/(T+θ) with θ ≈ −22 K and μeff = 6.0(1) μB for T ≥ ca. 35 K, with a small deviation from this dependence at lower temperatures, indicating Mn2+ ions with localised magnetic moments and antiferromagnetic interactions.
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| 5. |
- Istomin, S. Ya., et al.
(författare)
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A neutron powder diffraction study of Na1-xSrxTaO3 (x=0.2 and 0.3)
- 2002
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Ingår i: Solid State Sciences. - 1293-2558 .- 1873-3085. ; 4:2, s. 191-195
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Tidskriftsartikel (refereegranskat)abstract
- Black powder samples of the reduced oxotantalates Na1-xSrxTaO3 x = 0.2 and 0.3 were prepared via solid state reactions from appropriate amounts of NaTaO3, Sr5Ta4O15 and Ta (99.99%) in sealed tantalum ampoules at 1500degreesC. They crystallize in variants of the perovskite type structure (a(per)). According to structural refinements from neutron powder diffraction data Na0.8Sr0.2Ta03 crystallizes orthorhombic in the GdFeO3 type structure with unit cell parameters a approximate to root2 x a(per), b approximate to 2 x a(per), c approximate to root2 x a(per) and space group Prima. The structure of the more reduced phase Na0.7Sr0.3TaO3 is tetragonal with unit cell parameters a approximate to root2 x a(per), c approximate to 2 x a(per) and space group P4/mbm.
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| 6. |
- Johansson, Börje, et al.
(författare)
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Chemical composition-elastic property maps of austenitic stainless steels
- 2003
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Ingår i: Solid State Sciences. - 1293-2558 .- 1873-3085. ; 5:6, s. 931-936
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Tidskriftsartikel (refereegranskat)abstract
- Despite a tremendous development during the last decades, both as regards computer power and methodology, it has remained impossible to treat steel at a fundamental atomic level. However, recently we have shown [L. Vitos, P.A. Korzhavyi, B. Johansson, Phys. Rev. Lett. 88 (2002) 155501] that the most efficient theories of random substitutional alloys combined with advanced numerical techniques have made possible to establish a theoretical insight to the electronic structure of stainless steels. Here a detailed description of the quantum-mechanical modeling of austenitic stainless steels is presented. We adopt an ab initio electronic structure calculation method based on the coherent potential approximation, implemented within the framework of the exact muffin tin orbitals theory, to map the chemical composition distributions of austenitic stainless steels into the elastic property distributions. The so generated database can be fruitfully used in the design of new class of steel alloys.
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| 7. |
- Valldor, M., et al.
(författare)
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The structure of the new compound YBaCo4O7 with a magnetic feature
- 2002
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Ingår i: Solid State Sciences. - 1293-2558 .- 1873-3085. ; 4:7, s. 923-931
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Tidskriftsartikel (refereegranskat)abstract
- Single crystals and pure powder samples of the new compound YBaCo4O7 have been obtained by solid-state reactions, using different temperature programs. From X-ray powder diffraction the structure was determined as hexagonal, space group P6(3)mc. having the cell parameters a = 6.2982(4) and c = 10.2467(9) Angstrom. This phase is isostructural with that previously reported for LuBaZn3.09Al0.91O7. Refinements of powder neutron diffraction data collected at two different temperatures and X-ray single crystal data at room temperature, agree well. Changes with temperature in the relative positions of Co and its surrounding oxygen atoms are the only geometrical manifestation of a probable spin-glass transition at about 65 K from the high temperature paramagnetic state.
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| 8. |
- Zhu, Bin, et al.
(författare)
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Calcium doped ceria-based materials for cost-effective intermediate temperature solid oxide fuel cells
- 2003
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558 .- 1873-3085. ; 5:8, s. 1127-1134
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies preparation and characterization of the calcium doping ceria (CCO) and carbonate composite materials. The material preparation was performed based on an oxalate co-precipitation. Various material characterizations were carried on the material phase structure based on XRD, TG/DSC and their fuel cell applications. The CCO materials showed a two-phase composite with very high ionic conductivity, 0.01 to 0.5 S cm(-1) between 400 and 700degreesC. Using the CCO-composites as the electrolytes for intermediate temperature solid oxide fuel cells (ITSOFC) a high performance, e.g., 600 mW cm(-2) was demonstrated at 600degreesC.
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| 9. |
- Adam, Rania Elhadi, 1978-, et al.
(författare)
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Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light
- 2020
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Ingår i: Solid State Sciences. - : Elsevier. - 1293-2558 .- 1873-3085. ; 99
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Tidskriftsartikel (refereegranskat)abstract
- Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 °C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2θ angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.
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| 10. |
- Baron, V, et al.
(författare)
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Neutron powder diffraction study of Mn-bearing hematite, α-Fe2−xMnxO3, in the range 0 x 0.176
- 2005
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Ingår i: Solid State Sciences. - : Elsevier BV. - 1293-2558. ; 7:6, s. 753-759
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Tidskriftsartikel (refereegranskat)abstract
- A detailed neutron powder diffraction and calorimetric study was conducted to determine the influence of increasing Mn-substitution on the crystal and the magnetic structures of hematite, α-Fe2O3. The study was initiated to determine, if Mn substitution may be responsible for unusual ferromagnetic properties of natural hematite samples from the Kalahari Mn field, South Africa. Natural as well as synthetic Mn-bearing hematite samples with the compositional range Fe2−xMnxO3 (x=0 to 0.176) were examined. Calorimetric measurements were performed to determine the Néel TN and the Morin TM temperature transitions. All studied hematite samples, irrespective of chemical composition, display weak ferromagnetism at 295 K and coexistence of weak ferromagnetic and antiferromagnetic phases at 10 K. A slight decrease of the total magnetic moment and TM but a drastic decrease of TN can be attributed to increasing Mn-substitution. The results illustrate that Mn substitution may contribute but cannot be the sole reason for the unusual magnetic properties of natural hematite samples.
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