Correlation between the structure and the spin state in R{sub 1-x}Sr{sub x}CoO{sub 3} (R=La, Pr, and Nd)
- University of Texas at Austin, 1 University Station, C2201, Austin, Texas 78712 (United States)
- Department of Crystalline Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)
The crystal structures of the perovskites R{sub 1-x}Sr{sub x}CoO{sub 3} (R=La, Pr, and Nd) with 0{<=}x{<=}0.3 were refined from x-ray powder diffraction spectra with the Rietveld method. The result of the Rietveld analyses indicates the presence of three unequal Co-O bonds with different lengths for all samples, and we found that the difference between the two Co-O(2) bond lengths increases with temperature and Sr content. The intermediate-spin (IS) state of the Co{sup 3+} ion is Jahn-Teller (JT) active, and the structural data show that the concentration of Co{sup 3+} ions increases with temperature and Sr content. For the non-Sr-doped R=La sample, we observed only a small distortion at 90 K while the JT distortion was large at 300 K. With substitution of Sr for La, the distortion at 90 K was found to increase. This observation can be accounted for by the increased stability of the IS state with Sr doping. On the other hand, the distortion was small even at 300 K for nondoped PrCoO{sub 3} and NdCoO{sub 3}, indicating that the low-spin state is stable up to higher temperatures than in LaCoO{sub 3}. The distortion at 90 K was larger for the Sr-doped samples as in the R=La system, but the Sr content at which the JT distortion started to increase significantly was larger than that in the R=La system.
- OSTI ID:
- 21052713
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 14; Other Information: DOI: 10.1103/PhysRevB.76.144116; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis, structure and electric studies for La{sub 0.7}A{sub 0.3}Mn{sub 0.96}(In{sub x}Al{sub (1-x)}){sub 0.04}O{sub 3}; A=Ca and Sr perovskites
Thermoelectric properties of polycrystalline La{sub 1-x}Sr{sub x}CoO{sub 3}
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOND LENGTHS
COBALT IONS
COBALT OXIDES
CORRELATIONS
CRYSTAL STRUCTURE
DOPED MATERIALS
JAHN-TELLER EFFECT
LANTHANUM COMPOUNDS
NEODYMIUM COMPOUNDS
PEROVSKITES
PRASEODYMIUM COMPOUNDS
SPECTRA
SPIN
STRONTIUM COMPOUNDS
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
X-RAY DIFFRACTION