The pressure-temperature phase diagram of MgH 2 and isotopic substitution
The pressure-temperature phase diagram of MgH 2 and isotopic substitution
复制标题
MgH 2 的压力-温度相图和同位素取代
DOI：
10.1088/0953-8984/23/30/305403
复制
发表时间：
2011
期刊：
影响因子：
1.7
通讯作者：
Moser D
中科院分区：
文献类型：
--
作者：
Moser D
密度泛函从头计算热力学是计算相图的有力工具。该方法通常应用于标准压力p= 1 bar，并假设吉布斯能等于亥姆霍兹能。在这项工作中，我们已经计算了吉布斯自由能，以研究在高达10 GPa（100 kbar）的高压下MgH2的释放温度和相变化。氘（或氚）对氢的同位素替代对相图没有强烈的影响。这些考虑对于（i）在高压下合成新型置换镁基材料和（ii）确定用于在高压下计算相图的正确参考状态是极其重要的。计算结果与实验数据进行了比较，获得了在现场中子衍射测量。
Computational thermodynamics using density functional theory ab initio codes is a powerful tool for calculating phase diagrams. The method is usually applied at the standard pressure of p= 1 bar and where the Gibbs energy is assumed to be equal to the Helmholtz energy. In this work, we have calculated the Gibbs energy in order to study the release temperature and phase modifications of MgH 2 at high pressures up to 10 GPa (100 kbar). The isotopic substitution of hydrogen with deuterium (or tritium) does not bring about any strong effects on the phase diagram. These considerations are of extreme importance for (i) the synthesis of novel substitutional magnesium based materials at high pressure and (ii) the determination of the correct reference states for the calculation of phase diagrams at high pressure. The calculated results are compared with experimental data obtained with an in situ neutron diffraction measurement.