Preparation, crystal structures and rapid hydration of P2- and P3-type sodium chromium antimony oxides
- Southern Federal University, 7 ul. Zorge, Rostov-na-Donu 344090 (Russian Federation)
Two new Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2} compounds have been prepared by solid-state reactions in argon. Their structures have been determined by the X-ray Rietveld method. Both new phases together with NaCrO{sub 2}-based solid solution comprise brucite-like layers of edge-shared (Cr,Sb)O{sub 6} octahedra but differ by packing mode of the layers and coordination of the interlayer Na{sup +} ions. A P3 phase exists at x{approx}0.5-0.58. It is rhombohedral (R3-bar m), a=2.966, c=16.937 A at x{approx}0.58, with 29% Na{sup +} occupancy of trigonal prisms. A P2 phase exists at x{approx}0.6-0.7. It is hexagonal (P6{sub 3}/mmc), a=2.960, c=11.190 A at x{approx}0.7, with 37% and 33% Na{sup +} occupancy of two non-equivalent trigonal prisms. Both P2 and P3 phases rapidly absorb moisture in air; packing mode is preserved, the a parameter changes slightly but c increases by 24-25%. Very high sodium ion conductivity is predicted for both P2 and P3 anhydrous phases. -- Graphical Abstract: Polyhedral presentation of layered structures of Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2}. (Cr,Sb)O{sub 6} octahedra are green. Part of the sodium prisms are open to show short distances between sodium sites which cannot be occupied simultaneously. Display Omitted highlights: > Two new layered Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2} phases, P2 and P3, have been prepared in argon. > Interlayer O-O distances are larger than in Na{sub x}(M,Ti)O{sub 2} analogs (M=Cr,Ni,Li). > As a result, both rapidly hydrate in air with c-axis expansion of 24-25%. > Bottleneck radii are also larger, and this predicts very high Na{sup +}-ion conductivity.
- OSTI ID:
- 21504070
- Journal Information:
- Journal of Solid State Chemistry, Vol. 184, Issue 5; Other Information: DOI: 10.1016/j.jssc.2011.03.011; PII: S0022-4596(11)00108-3; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTIMONY OXIDES
ARGON
CHROMITES
CHROMIUM COMPOUNDS
HCP LATTICES
HYDRATES
HYDRATION
LAYERS
SODIUM COMPOUNDS
SODIUM IONS
SOLID ELECTROLYTES
SOLID SOLUTIONS
TRIGONAL LATTICES
X RADIATION
ALKALI METAL COMPOUNDS
ANTIMONY COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DISPERSIONS
ELECTROLYTES
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUIDS
GASES
HEXAGONAL LATTICES
HOMOGENEOUS MIXTURES
IONIZING RADIATIONS
IONS
MIXTURES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
RARE GASES
SOLUTIONS
SOLVATION
TRANSITION ELEMENT COMPOUNDS