Structure and magnetic properties in mixed valent LaCr0.7Cu0.3O3 ceramics

Single-phase LaCr0.7Cu0.3O3 ceramics was fabricated successfully using high pressure sintering method. A mixed valent state with the coexistence of Cr2+，Cr3+ and Cr4+ was confirmed by X-ray photoelectron spectroscopy measurement. Magnetic measurement results indicate that in addition to antiferromagnetic superexchange interaction of Cr3+ -O2- -Cr3+ accompanied by weak ferromagnetism at high temperature, two types of short-range order ferromagnetism can be observed at low temperature, which could be attributed to double exchange interactions of Cr2+ -O2- -Cr3+ and Cr3+ -O2- -Cr4+, respectively. The results here would enrich the understanding on magnetic interactions in rare-earth chromites.