High-pressure synthesis, structure and magnetic properties of LaCrO3 ceramics

Single-phase LaCrO3 ceramics was synthesized successfully by the solid state sintering method under high pressure (5 GPa). X-ray diffraction measurements suggest that the high-pressure synthesized sample is well-crystallized, but the cell volume is larger than that of the sample synthesized under ambient pressure, which can be ascribed to the occurrence of Cr2+ converted form part of Cr3+. Such mixed valent state with coexistence of Cr2+ and Cr3+ could be confirmed by X-ray photoelectron spectroscopy measurements. Magnetic measurement results indicate that in addition to antiferromagnetic superexchange interaction of Cr3+-O-Cr3+ network accompanied by weak ferromagnetism at high temperature, another kind of ferromagnetic behavior can be observed at low temperature (below 30 K), which could be attributed to double exchange interaction of Cr2+-O-Cr3+ networks.