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Preparation, crystal structures and rapid hydration of P2- and P3-type sodium chromium antimony oxides

✍ Scribed by A.A. Pospelov; V.B. Nalbandyan


Book ID
104030816
Publisher
Elsevier Science
Year
2011
Tongue
English
Weight
392 KB
Volume
184
Category
Article
ISSN
0022-4596

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✦ Synopsis


Two new Na x [Cr (1 ΓΎ x)/2 Sb (1 Γ€ x)/2 ]O 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 2 -based solid solution comprise brucite-like layers of edge-shared (Cr,Sb)O 6 octahedra but differ by packing mode of the layers and coordination of the interlayer Na ΓΎ ions. A P3 phase exists at x E 0.5-0.58. It is rhombohedral (R3 Β―m), a ΒΌ 2.966, c ΒΌ 16.937 Γ… at x E 0.58, with 29% Na ΓΎ occupancy of trigonal prisms. A P2 phase exists at x E0.6-0.7. It is hexagonal (P6 3 /mmc), a ΒΌ 2.960, c ΒΌ 11.190 Γ… at x E 0.7, with 37% and 33% Na ΓΎ 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.


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