Formation of unusual Cr5+ charge state in CaCr0.5Fe0.5O3 perovskite

• 来源期刊: 中国物理B（英文版）
• 关键词: high pressure synthesis perovskite valence state
• 年，卷（期）: 2018,（3）
• 页码范围: 433-438
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/3/037503

摘要

A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions.It crystallizes in a B-site disordered Pbnm perovskite structure.The charge combination is determined to be CrS+/Fe3+ with the presence of unusual Cr5+ state in octahedral coordination,although Cr4+ and Fe4+ occur in the related perovskites CaCrO3 and CaFeO3.The randomly distributed Cr5+ and Fe3+ spins lead to short-range ferromagnetic coupling,whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe3+-O-Fe3+ interaction.In spite of the B-site Cr5+/Fe3+ disorder,the compound exhibits electrical insulating behavior.First-principles calculations further demonstrate the formation of CaCr0.55+Fe0.53+O3 charge combination,and the electron correlation effect of Fe3+ plays an important role for the insulting ground state.CaCr0.5Fe0.5O3 provides the first Cr5+ perovskite system with octahedral coordination,opening a new avenue to explore novel transition-metal oxides with exotic charge states.