Magnetic Properties and Crystal Distortions of BiMnO3and BiCrO3

Magnetic perovskites BiMnO 3 and BiCrO 3 were synthesized under very high pressures. There are phase transitions at 500°K and 410°K at atmospheric pressure for BiMnO 3 and BiCrO 3 respectively, and the crystal distortion of each phase was determined. BiMnO 3 is ferromagnetic below 103°K, while BiCrO 3 is inferred to be antiferromagnetic below 123°K accompanied with weak ferromagnetic moment. BiCrO 3 has an abnormally large effective Bohr magneton number at room temperature phase. The distortion of BiMnO 3 decreases slightly below the ferromagnetic Curie point.