Energetic prediction on the stability of A2Mg2Si7, A2Mg4Si3, and AMgSi in the A2Si-Mg2Si system (A=Ca, Sr and Ba) and their calculated electronic structure
Energetic prediction on the stability of A2Mg2Si7, A2Mg4Si3, and AMgSi in the A2Si-Mg2Si system (A=Ca, Sr and Ba) and their calculated electronic structure
复制标题
A2Si-Mg2Si体系（A=Ca、Sr和Ba）中A2Mg2Si7、A2Mg4Si3和AMgSi稳定性的能量预测及其计算的电子结构
DOI：
10.1016/j.jallcom.2013.12.015
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发表时间：
2014
影响因子：
6.2
通讯作者：
K. Takarabe
中科院分区：
文献类型：
--
作者：
Y. Imai;Y. Mori;S. Nakamura;K. Takarabe
用密度泛函理论和Perdew-Wang广义梯度近似计算了A_2Si-Mg_2Si系统中A_2Mg_4Si_3、A_2Mg_(12)Si_7和AMgSi(A_w=0.Ca，Sr和Ba)的相对稳定性。结果表明：(1)与A2Si和Mg2Si等摩尔混合物相比，AMgSi很稳定；(2)Ba2Mg4Si3和Sr2Mg4Si3也很稳定；(3)Ca2Mg4Si3和Ca2Mg12Si7的稳定性不如CaMgSi和Mg2Si的混合物稳定；(4)Ba2Mg12Si7的稳定性比Sr2Mg4Si3(或，SrMgSi3)和Mg2Si的混合物在能量上不稳定。Sr2Mg12Si7的存在可能是由于振动和/或构型熵造成的，这在本研究中没有讨论。从计算的态密度可知，化合物具有p型和n型两种特征，这取决于化合物中SrMgSi和Mg2Si的比例。
In order to evaluate the relative stability of A2Mg4Si3, A2Mg12Si7, and AMgSi (A = Ca, Sr, and Ba) in the A2Si–Mg2Si system, electronic energy changes in the formation of these compounds were calculated using a density-functional theory with the Perdew–Wang generalized gradient approximations. It was found that (1) AMgSi’s are quite stable compared to equi-molar mixture of A2Si and Mg2Si, (2) Ba2Mg4Si3and Sr2Mg4Si3are also stable, (3) Ca2Mg4Si3and Ca2Mg12Si7are less stable than the mixture of CaMgSi and Mg2Si, and (4) Stability of Ba2Mg12Si7is a tender subject and Sr2Mg12Si7is energetically unstable compared to the mixture of Sr2Mg4Si3(or, SrMgSi) and Mg2Si. The presence of Sr2Mg12Si7may be due to the vibrational and/or configurational entropy, which are not treated in the present study. From the calculated electronic densities of state, complex compounds of SrMgSi and Mg2Si have bothp-type andn-type character, depending on the ratio of SrMgSi and Mg2Si in that compound.