First-principles study of cation disordering in MgAl2O4 spinel with cluster expansion and Monte Carlo simulation
First-principles study of cation disordering in MgAl2O4 spinel with cluster expansion and Monte Carlo simulation
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DOI：
10.1103/physrevb.73.094116
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发表时间：
2006-03
影响因子：
3.7
通讯作者：
Atsuto Seko;Koretaka Yuge;F. Oba;A. Kuwabara;I. Tanaka;Tomoyuki Yamamoto
中科院分区：
文献类型：
--
作者：
Atsuto Seko;Koretaka Yuge;F. Oba;A. Kuwabara;I. Tanaka;Tomoyuki Yamamoto
采用第一性原理总能量计算、团簇展开和正则蒙特卡罗模拟相结合的方法，研究了$\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$尖晶石中阳离子无序的温度依赖性。预测尖晶石晶胞内可能的阳离子无序结构的形成能都是正的，这表明基态是正常的尖晶石，这与广泛接受的观点一致。通过考虑许多有效的团簇相互作用，直到四重态，阳离子无序与温度的关系被很好地再现。根据比热的反常，估算出有序-无序转变温度约为860美元。$\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$体积的团簇膨胀表明，随着阳离子交换量的增加，体积减小。
The temperature dependence of cationic disorder in $\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$ spinel is investigated using a combination of first-principles total-energy calculations, a cluster expansion, and canonical Monte Carlo simulations. The formation energies of the possible cation-disordered structures within the spinel unit cell are predicted to be all positive, suggesting that the ground state is the normal spinel in consistency with a widely accepted view. The temperature dependence of cationic disorder is well reproduced by considering many effective cluster interactions up to quadruplets. The order-disorder transition temperature is estimated at about $860\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ based on the anomaly of specific heat. The cluster expansion of the volume of $\mathrm{Mg}{\mathrm{Al}}_{2}{\mathrm{O}}_{4}$ indicates that it decreases as more cations exchange.