Valence Change of A鈥?Site Mn by A-Site Doping in La1鈥?i>xNaxMn3Ti4O12

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• 作者：Takenori Tohyama ; Mark S. Senn ; Takashi Saito ; Wei-tin Chen ; Chiu C. Tang ; J. Paul Attfield ; Yuichi Shimakawa
• 刊名：Chemistry of Materials
• 出版年：2013
• 出版时间：January 22, 2013
• 年：2013
• 卷：25
• 期：2
• 页码：178-183
• 全文大小：310K
• 年卷期：v.25,no.2(January 22, 2013)
• ISSN：1520-5002

文摘

A-site-ordered perovskites La_1鈥?i>xNa_xMn₃Ti₄O₁₂ with (x = 0, 0.5, 1) were synthesized under high-pressure and high-temperature conditions, and their crystal structures and magnetic properties were investigated. Ti/Mn occupancies at the B site were also examined by using resonant X-ray diffraction, and the results confirm that they are stoichiometric with high Ti/Mn site selectivity. Substitution of Na⁺ for some of the La³⁺ changes the valence state of the A鈥?site Mn but not of the B-site Ti, and thus the compositions of the synthesized samples are expressed as La_1鈥?i>xNa_xMn^{(5+2x)/3}+₃Ti⁴⁺₄O₁₂. The magnetic properties change from spin-glass-like to antiferromagnetic to spin-glass-like behavior according to the valence states of A鈥?site Mn.

Keywords:

A-site-ordered perovskites; high-pressure synthesis; resonant X-ray diffraction; magnetic properties; valence states of cations