Mg-Ti-H 体系晶体结构与相稳定性的第一性原理计算

采用基于密度泛函理论的第一性原理赝势平面波方法计算了不同Ti 含量的MgxTi（1-x）H2 （x=0.25,0.5,0.75,0.875）体系的平衡晶格结构、总能量及稳定性.结果表明：氢原子在晶胞中的位置接近于四面体间隙位置; H―Ti 原子间距小于H―Mg原子间距,表明Ti 较Mg具有更强的＂亲氢性＂,Ti 原子在吸引周围H原子的同时削弱了H―Mg键的强度; 随Ti 含量的增加,体系的稳定性和脱氢温度均降低,且MgxTi（1-x）H2体系与MgH2相比,稳定性更差,脱氢温度更低,表明Ti 可降低MgxTi（1-x）H2体系的分解温度并加速其脱氢动力学过程,表现出脱氢催化活性....

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Bibliographic Details
Published in物理化学学报 Vol. 27; no. 12; pp. 2793 - 2798
Main Author 杜晓明 李武会 黄勇 吴尔冬
Format Journal Article
LanguageChinese
Published 沈阳理工大学材料科学与工程学院,沈阳,110159%中国科学院金属研究所,沈阳,110016 2011
Subjects
MgxTi（1-x）H2
晶体结构
稳定性
赝势平面波
赝势平面波
晶体结构
MgxTi(1-x)H2
稳定性
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ISSN1000-6818
DOI10.3866/PKU.WHXB20112793

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Summary:采用基于密度泛函理论的第一性原理赝势平面波方法计算了不同Ti 含量的MgxTi（1-x）H2 （x=0.25,0.5,0.75,0.875）体系的平衡晶格结构、总能量及稳定性.结果表明：氢原子在晶胞中的位置接近于四面体间隙位置; H―Ti 原子间距小于H―Mg原子间距,表明Ti 较Mg具有更强的＂亲氢性＂,Ti 原子在吸引周围H原子的同时削弱了H―Mg键的强度; 随Ti 含量的增加,体系的稳定性和脱氢温度均降低,且MgxTi（1-x）H2体系与MgH2相比,稳定性更差,脱氢温度更低,表明Ti 可降低MgxTi（1-x）H2体系的分解温度并加速其脱氢动力学过程,表现出脱氢催化活性.
Bibliography:11-1892/06
First-principles calculations were performed to determine the equilibrium crystal structures, energetic properties, and stability of MgxTi（1-x）H2 （x=0.25, 0.5, 0.75, 0.875） systems containing different amounts of titanium using the pseudopotential plane-wave method based on density functional theory. The calculation results show that the hydrogen atoms in the MgxTi（1-x）H2 hydrides roughly occupy the tetrahedral interstitial sites. The calculated H --Ti distances are less than the H- Mg distances. This indicates that Ti has a more notable affinity for hydrogen than Mg. The bonding strength of H -- Mg is weaker when the Ti atom attracts surrounding hydrogen atoms. The stabilization and dehydrogenation temperatures of the hydrides MgxTi（1-x）H2 are lower than those of MgH2 with an increasing Ti content. This indicates that titanium can reduce the decomposition temperature of the MgxTi（1-x）H2 hydrides and play a significant catalytic role in improving the dehydrogenation dynamic properties of the MgxTi（1
ISSN:1000-6818
DOI:10.3866/PKU.WHXB20112793