Competition of Covalency between CrIII-O and TaV-O Bonds in the Perovskites Ca2CrTaO6 and Sr2CrTaO6

✍ Scribed by Jin-Ho Choy; Jae-Hyun Park; Seung-Tae Hong; Dong-Kuk Kim

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 467 KB
• Volume: 111
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1241

✦ Synopsis

According to the Rietveld refinement, the perovskites (\mathrm{Ca}{2} \mathrm{CrTaO}{6}) and (\mathrm{Sr}{2} \mathrm{Cr}^{2} \mathrm{TaO}{6}) are found to have space groups (P 2_{1} / n) (monoclinic, (a=5.4199(1) \AA, b=5.4936(1) \AA, c=) (7.7108(2) \AA), and (\beta=90.02(1)^{\circ}) ) and (F m 3 m) (cubic, (a=7.8837(1)) (\AA) ), respectively, with partial disordering of (\mathrm{Cr}) and (\mathrm{Ta}) ions. Structural analysis indicated that the (\mathrm{Cr}-\mathrm{O}) bond distance is shorter than the Ta-O distance in both compounds. XANES for (T) Ta (L_{\text {III }}) edge and EPR spectroseopic analyses and magnetic susceptibility measurements were performed to obtain information on the covalency between (B) cations ( (B=C r), Ta) and oxygen ions. The variation of crystal structure and magnetic properties in the two compounds could be explained by the size and the covalent bonding nature between metal and oxygen ions. 1994 Academic Press, Inc.