Experimental and computational investigations of LaNi(5-x)Alx (x = 0,0.25, 0.5, 0.75 and 1.0) tritium-storage alloys  

作　　者：Guoliang Liu Demin Chen Yuanming Wang Ke Yang 

机构地区：[1]Institute of Metal Research, Chinese Academy of Sciences ,Shenyang 110016, China [2]University of Chinese Academy of Sciences, Beijing 110049, China

出　　处：《Journal of Materials Science & Technology》2018年第9期1699-1712,共14页材料科学技术（英文版）

基　　金：support from the National Natural Science Foundation of China under the grant No. 51271176

摘　　要：Although already scientists in recent years have reported some experimental and theoretical results of LaNi-Al series of tritium-storage alloys, several key aspects remain the subject of considerable debate. In an effort to interpret some of these unknowns, we have performed experimental and theoretical investigations for LaNi（5-x）Alx（x = 0, 0.25, 0.5, 0.75 and 1.0） tritium-storage alloys. Firstly, the XRD characterization indicates that the unit cell volumes of LaNi（5-x）Alx increase with Al content in alloys. Secondly, the PCisotherm measurement of LaNi（5-x）Alxalloys shows that their hydrogen absorption/desorption plateau pressures reduce with the increase of Al content while their plateau widths narrow simultaneously. The deuterium absorption/desorption plateaus have a similar trend to hydrogen＇s except for their plateaus being higher than hydrogen＇s. To explain the above experimental findings, a series of calculations based on density functional theory（DFT） and frozen phonon approach have been performed. The results manifest that：（1） the partial substitutions of Al for Ni reduce the hydrogen formation energies of LaNi（5-x）AlxH and the number of available interstitial sites, and therefore lead to the absorption/desorption plateau pressures being reduced and the plateau widths being narrowed down at the same experimental temperatures;（2） the covalent interaction between H and Ni is an important factor for estimating the stability of LaNi（5-x）Alx-H system;（3） since the calculated enthalpy change H is generally more accurate than the calculated entropy change S with respect to the corresponding experimental value for each LaNi（5-x）AlxH（or D）, the curves of H vs. hydrogen storage capacity instead of Van＇t Hoff relation, can be used to predict the experimental plateau pressures of LaNi（5-x）Alx-H（D or T） at a given temperature;（4） the hydrogen isotope effect of LaNi（5-x）Alx-H（D or T） system can be quantitatively described as a linearity relatAlthough already scientists in recent years have reported some experimental and theoretical results of LaNi-Al series of tritium-storage alloys, several key aspects remain the subject of considerable debate. In an effort to interpret some of these unknowns, we have performed experimental and theoretical investigations for LaNi（5-x）Alx（x = 0, 0.25, 0.5, 0.75 and 1.0） tritium-storage alloys. Firstly, the XRD characterization indicates that the unit cell volumes of LaNi（5-x）Alx increase with Al content in alloys. Secondly, the PCisotherm measurement of LaNi（5-x）Alxalloys shows that their hydrogen absorption/desorption plateau pressures reduce with the increase of Al content while their plateau widths narrow simultaneously. The deuterium absorption/desorption plateaus have a similar trend to hydrogen＇s except for their plateaus being higher than hydrogen＇s. To explain the above experimental findings, a series of calculations based on density functional theory（DFT） and frozen phonon approach have been performed. The results manifest that：（1） the partial substitutions of Al for Ni reduce the hydrogen formation energies of LaNi（5-x）AlxH and the number of available interstitial sites, and therefore lead to the absorption/desorption plateau pressures being reduced and the plateau widths being narrowed down at the same experimental temperatures;（2） the covalent interaction between H and Ni is an important factor for estimating the stability of LaNi（5-x）Alx-H system;（3） since the calculated enthalpy change H is generally more accurate than the calculated entropy change S with respect to the corresponding experimental value for each LaNi（5-x）AlxH（or D）, the curves of H vs. hydrogen storage capacity instead of Van＇t Hoff relation, can be used to predict the experimental plateau pressures of LaNi（5-x）Alx-H（D or T） at a given temperature;（4） the hydrogen isotope effect of LaNi（5-x）Alx-H（D or T） system can be quantitatively described as a linearity relat

关 键 词：Hydrogen isotope storage material lectron structure calculation Thermodynamic property calculation 

分 类 号：TB2[一般工业技术—工程设计测绘]