Search results for "Solid solution"
showing 10 items of 308 documents
The Li Ni0.2Mn0.2Co0.6O2 electrode materials: A structural and magnetic study
2012
Graphical abstract: EPR signal of the Li{sub 0.6}Co{sub 0.6}Ni{sub 0.2}Mn{sub 0.2}O{sub 2} composition showing that Mn{sup 4+} ions are the solely paramagnetic ions in the structure. Highlights: Black-Right-Pointing-Pointer LiCo{sub 0.6}Ni{sub 0.2}Mn{sub 0.2}O{sub 2} was prepared by the combustion method with sucrose as a fuel. Black-Right-Pointing-Pointer Chemical delithiaition was performed by using NO{sub 2}BF{sub 4} oxidizing agent. Black-Right-Pointing-Pointer The rhombohedral symmetry was preserved upon lithium removal. Black-Right-Pointing-Pointer Lithium extraction leads to Ni{sup 2+} oxidation to Ni{sup 4+} followed by Co{sup 3+} oxidation. Black-Right-Pointing-Pointer The EPR narr…
Ab initio calculations of the atomic and electronic structure of layered Ba0.5Sr0.5TiO3 structures
2005
Abstract Understanding of the atomic and electronic structure of Ba c Sr 1 − c TiO 3 (BST) solid solutions is important for several applications including the non-volatile ferroelectric memories (dynamic random access memory, DRAM). We present results of ab initio calculations of several spatial arrangements of Ba 0.5 Sr 0.5 TiO 3 solid solutions based on DFT-HF B3PW hybrid method. We calculate the atomic and electronic structure, the effective charges, interatomic bond populations, the electronic density distribution, and densities of states for three layered structures with the same composition. The suggested method reproduces experimental lattice parameters of both pure BaTiO 3 and SrTi…
Chemical disorder and Pb207 hyperfine fields in the magnetoelectric multiferroic Pb(Fe1/2Sb1/2)O3 and its solid solution with Pb(Fe1/2Nb1/2)O3
2018
We report on the results of magnetic susceptibility, electron paramagnetic resonance, and $^{207}\mathrm{Pb}$ nuclear magnetic resonance (NMR) studies of the magnetoelectric multiferroic $\mathrm{Pb}(\mathrm{F}{\mathrm{e}}_{1/2}\mathrm{S}{\mathrm{b}}_{1/2}){\mathrm{O}}_{3}$ (PFS) ceramic, as well as its solid solution with $\mathrm{Pb}(\mathrm{F}{\mathrm{e}}_{1/2}\mathrm{N}{\mathrm{b}}_{1/2}){\mathrm{O}}_{3}$ (PFN) of different degrees of the 1:1 ordering of magnetic $\mathrm{F}{\mathrm{e}}^{3+}$ and nonmagnetic $\mathrm{S}{\mathrm{b}}^{5+}$ ions. The ordering has been studied by x-ray diffraction (XRD) and NMR methods. In particular, two spectral lines, originating from the ordered and dis…
Ab initio simulation of (Ba,Sr)TiO3 and (Ba,Ca)TiO3 perovskite solid solutions
2019
This research was supported by the ERA-NET HarvEnPiez project. Many thanks to R. Dovesi, M.M. Kržmanc and D. Gryaznov for fruitful discussions.
Short and Medium Range Order in Se1-xTexGlasses
1997
Complementary XAFS measurements (LURE and NSLS) of Se 1 - x Te x glasses have been carried out on both the Se and Te K-edges at low and room temperatures. Using a multi-shell best fit analysis procedure, we have reconstructed the Se and Te local environment: (i) first shell intrachain nearest neighbors (Se-Se 1 , Se-Te 1 , Te-Se 1 ,and Te-Te 1 ); (ii) second shell intrachain (Se-Se 2 and Se-Te 2 ) and interchain next nearest neighbors (Se⇔Se 3 single scattering in the chains Se-Se 1 -Se 3 and Se-Te 1 -Se 3 ). For the first and second coordination shells we suggest that the intrachain chemical order increases with Te content. On the other hand, we propose a model of random distribution of Se…
Quantum chemical modelling of polarons and perovskite solid solutions
2001
Abstract Following our previous study [J. Phys.: Condens. Matter 10 (1998) 6271] of a single Nb impurity and Nb clusters in KTaO 3 , we present results of the calculations for a series of perovskite KNb x Ta 1− x O 3 (KTN) solid solutions ( x =0, 0.125, 0.25, 0.75, 1). The quantum chemical method of the intermediate neglect of the differential overlap (INDO) combined with the large unit cell (LUC) periodic model is used. According to the INDO calculations, Nb impurity becomes off-center in KTaO 3 already at the lowest studied concentrations ( x =0.125), in a good agreement with XAFS measurements. We compare our results with previous ab initio FP-LMTO calculations. Quantum chemical calculati…
Pd–Pt alloys: correlation between electronic structure and hydrogenation properties
2001
Abstract Palladium and its alloys have been extensively studied because of their faculty to store reversibly hydrogen isotopes. Here, the substitution of palladium with platinum is investigated. Thermodynamical studies have shown an anomalous behaviour regarding to the classical models. This original behaviour is explained by the study of the electronic structure of the binary solid solutions. The drastic decrease of the hydrogen solubility in the Pd–Pt alloys is accounted for by the filling up of the palladium conduction band by the valence electrons of platinum. The anomalous decrease of the stability of the hydride is explained by the large broadening of the valence band due to the subst…
Structure and Physical Properties of Na1/2Bi1/2TiO3-CdTiO3Solid Solutions
2011
Behaviour of ferroelectric properties in Na1/2Bi1/2TiO3-CdTiO3 solid solutions correlates with dependence of lattice symmetry versus concentration of constituents. However, some overlapping is observed in concentration range close to the morphotropic phase boundary. The properties of dielectric permittivity, characteristic for relaxor ferroelectrics, diminish, if concentration of CdTiO3 increases, but it is not influenced by the change of crystallographic symmetry. The electromechanical properties are mostly pronounced in the range of cubic-tetragonal morphotropic phase boundary.
Vapor phase epitaxy of Hg1−xCdxI2 on sapphire
1998
Abstract We demonstrate the possibility of growing Hg 1− x Cd x I 2 layers on sapphire substrates by vapor-phase epitaxy (VPE). The successful growth has been carried out using an α-HgI 2 polycrystalline source and a CdTe buffer layer grown on sapphire by metalorganic vapor phase epitaxy (MOVPE) before the Hg 1− x Cd x I 2 VPE growth. The Hg 1− x Cd x I 2 /sapphire 20–40 μm thick layers with a uniform composition in the range of x =0.2–0.6 were grown at 220–250°C for 70–300 h. The layers were studied by scanning electron microscopy, energy disperse X-ray analysis and X-ray diffractometry. Results on the layer characterization are reported and the effect of VPE conditions on the layer proper…
On the solution growth of single crystals of solid solutions
1986
Abstract Homogeneous solid solution crystals are needed for studying the behaviour of systems with a glass state or incommensurate phases. A simple solution growth procedure is described. It is based on a temperature difference growth method with thermally enforced convection and the use of equilibrated solid and liquid solutions. First results of its application to the [(CH3)4N]2ZnCl 4−xBrx and the Rb1−x(NH4)xH2PO4 systems are presented.