Rodion V. Panin

Ordering of Pd2+ and Pd4+ in the Mixed-Valent Palladate KPd2O3

A new potassium palladate KPd(2)O(3) was synthesized by the reaction of KO(2) and PdO at elevated oxygen pressure. Its crystal structure was solved from powder X-ray diffraction data in the space group R3m (a = 6.0730(1) A, c = 18.7770(7) A, and Z = 6). KPd(2)O(3) represents a new structure type, consisting of an alternating sequence of K(+) and Pd(2)O(3)(-) layers with ordered Pd(2+) and Pd(4+) ions. The presence of palladium ions in di- and tetravalent low-spin states was confirmed by magnetic susceptibility measurements.

Synthesis and electrochemical performance of Li2Co1−xMxPO4F (M = Fe, Mn) cathode materials

Summary In the search for high-energy materials, novel 3D-fluorophosphates, Li2Co1− xFexPO4F and Li2Co1− xMnxPO4F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li2Co1− xFexPO4F and Li2Co1− xMnxPO4F, exhibited narrow ranges of solid solutions: x ≤ 0.3 and x ≤ 0.1, respectively. The Li2Co0.9Mn0.1PO4F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g−1 (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF4/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li2Co0.9Mn0.1PO4F material.

The effect of LiFeBO3/C composite synthetic conditions on the quality of the cathodic material for lithium-ion batteries

Composite electrode materials based on LiFeBO3 are synthesized under different conditions and studied as the cathodic materials for lithiumion batteries. Composites with different degrees of iron oxidation are synthesized by annealing in a closed system with the use of metal-oxide getters. Based on the results of cyclic voltammetry and galvanostatic cycling of samples with different Fe(II) contents, it is concluded that the surface composition is the determining factor for applicability of materials to reversible processes of inter-calation-deintercalation.

Stabilization of the LiMnBO3 monoclinic polymorph by the isovalent substitution of manganese for zinc

Samples of a LiMn1−xZnxBO3 (x = 0, 0.1, 0.15, 0.3) solid solution were synthesized for the first time and characterized. The modification of complex borate with the hexagonal or monoclinic unit cell symmetry is formed depending on the x value. The hexagonal phase has a narrow homogeneity range near x = 0 according to the X-ray powder diffraction data. The monoclinic form is characterized by a broader range of compositions with x = 0.15 and x = 0.3 inside. No ordering of manganese and zinc cations was observed in the whole studied composition range. The lithium diffusion coefficients were calculated by the molecular dynamics simulation for the both modifications of LiMnBO3 and LiMn0.85Zn0.15BO3 solid solution.

Crystal structure and properties of the Na_{1-x}Ru_{2}O_{4} phase

Sodium ruthenium(III,IV) oxide Na1−xRu2O4 was synthesized by the solid state reaction of Na2CO3 and RuO2 in inert atmosphere and characterized by X-ray powder diffraction, electron diffraction, and high-resolution transmission electron microscopy. The compound crystallizes in the CaFe2O4-type structure (space group Pnma, Z = 4, a = 9.2641(7) Å, b = 2.8249(3) Å, c = 11.1496(7) Å). Double rutile-like chains of the RuO6 octahedra form a three-dimensional framework, whose tunnels contain sodium cations. The structure contains two crystallographically independent sites of ruthenium atoms randomly occupied by the RuIII and RuIV cations. The superstructure with the doubled b parameter found for one of the samples under study using electron diffraction is caused, probably, by ordering of the Ru cations in the rutile-like chains. The Na1− xRu2O4 compound exhibits temperature-independent paramagnetism with χ0 = 1.9·10−4 cm3 (mole of Ru−1).

Synthesis and structure investigation of the Pb_{3}V(PO_{4})_{3} eulytite

Abstract Lead vanadium phosphate Pb3V(PO4)3 was synthesized by solid state reaction and characterized by X-ray single crystal and powder diffraction, electron microscopy, and magnetic susceptibility measurements. The crystal structure model of Pb3V(PO4)3 was refined using X-ray single crystal data ( a = 10.127 ( 1 ) A , S.G. I 4 ¯ 3 d , Z = 4 ). The compound has an eulytite-like structure and its average structure model may be presented as a three-dimensional network formed by strongly distorted mixed (Pb/VIII) metal-oxygen octahedra connected by edge sharing and forming corrugated chains. The octahedra are additionally linked by tetrahedral phosphate groups via corner sharing. Lead and vanadium atoms randomly occupy two close positions in the octahedra. The electron microscopy study revealed the presence of a rhombohedral superstructure with a sup = a sub × 2 and c sup = c sub × 75 / 2 indicating ordering in the structure. The same type of superstructure was found by us for two another lead-containing eulytite Pb3Fe(PO4)3 where Fe+3 has an ionic radius close to that of V+3. Magnetic susceptibility measurements revealed Curie–Weiss behavior for the Pb3V(PO4)3 compound.