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[摘要]：ScCrO3 and InCrO3 were synthesized at high pressure of 6 GPa and 1500 K. Crystal structures of ScCrO3 and InCrO3 were studied with synchrotron X-ray powder diffraction. They crystallize in the GdFeO3-type perovskite structure (space group Pnma, a = 5.35845(1) angstrom, b = 7.37523(1) angstrom, c = 5.03139(1) angstrom for ScCrO3 and a = 5.35536(1) angstrom, b = 7.54439(1) angstrom, c = 5.16951(1) A for InCrO3). The physical properties of ScCrO3 and InCrO3 were investigated with specific heat, ac/dc magnetization, and dielectric measurements and compared with those of YCrO3 with nonmagnetic Y3+ ions at the A site. Antiferromagnetic transitions occur at T-N = 73 K in ScCrO3 and 93 K in InCrO3 in agreement with the general trend of ACrO(3) (A = Y and rare earths) where T-N decreases with decreasing the radius of the A ions. Extremely weak ferromagnetism was found in ScCrO3 and InCrO3 in contrast to YCrO3. Ac magnetization measurements revealed some peculiarities in behavior of ScCrO3 and InCrO3, namely, double-peak anomalies just below T-N. Dielectric anomalies were observed in both compounds at T-N indicating magnetoelectric coupling in contact with YCrO3 where no dielectric anomalies were found. ScCrO3 and InCrO3 are very stable for high-pressure phases: no decomposition of ScCrO3 was observed after heating up to 1340 K in air, and InCrO3 only partially decomposed at 1340 K to give Cr2O3 and ambient- and high-pressure modifications of In2O3 as impurities. No anomalies were also found with differential scanning calorimetry up to 870 K and differential thermal analysis up to 1340 K, indicating the absence of high-temperature phase transitions. |
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