Correlation between Magnetic Properties and Mn/Co Atomic Order in LaMn0.5Co0.5O3+δ: I. Second-Order Nature in Mn/Co Atomic Ordering and Valence State
Correlation between Magnetic Properties and Mn/Co Atomic Order in LaMn0.5Co0.5O3+δ: I. Second-Order Nature in Mn/Co Atomic Ordering and Valence State
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DOI：
10.1021/cm0302781
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发表时间：
2003-11
影响因子：
8.6
通讯作者：
T. Kyōmen;Ryuta Yamazaki;M. Itoh
中科院分区：
文献类型：
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作者：
T. Kyōmen;Ryuta Yamazaki;M. Itoh
通过TG-DTA、粉末X射线衍射、磁化率和XANES研究了LaMn0.5Co0.5O3+δ在1300 K附近的弛豫现象以及Mn和Co原子的价态。DTA表明弛豫现象不是由一级相变引起的，弛豫时间的温度依赖性是热激活类型，这表明Mn/Co原子有序的有序-无序相变是二级类型。晶格参数，XANES，和磁化率测量的结果表明，有序相的基态价态是Mn 4 +/Co 2+和Mn 3 +/Co 3+的分数增加，无论是通过无序的Mn/Co原子配置或通过增加温度。
The relaxation phenomenon around 1300 K in LaMn0.5Co0.5O3+δ and their valence states of Mn and Co atoms were investigated by TG-DTA, powder X-ray diffraction, magnetic susceptibility, and XANES of two samples cooled at 10 Kh-1 in the range 1673−973 K and quenched from 1673 K. DTA clarified that the relaxation phenomenon is not due to a first-order phase transition and that the temperature dependence of relaxation time is a thermal activation type, which suggests that the order−disorder phase transition of Mn/Co atomic ordering is second-order type. The results of lattice parameters, XANES, and magnetic susceptibility measurements suggest that the ground valence state of the ordered phase is Mn4+/Co2+ and that a fraction of Mn3+/Co3+ is increased either by disordering the Mn/Co atomic configuration or by increasing temperature.