A thermal neutron scattering law for yttrium hydride
A thermal neutron scattering law for yttrium hydride
复制标题
氢化钇的热中子散射定律
DOI：
10.1051/epjconf/201714613005
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
J. Holmes
中科院分区：
文献类型：
--
作者：
M. Zerkle;J. Holmes
氢化钇（YH 2）由于其在高温下保持氢的上级能力而作为高温减速剂材料受到关注。本文报道了用从头算方法制备的氢化钇中束缚氢和束缚钇的热中子散射规律。采用密度泛函理论，结合交换关联能的广义梯度近似（GGA），模拟了YH 2的面心立方结构，计算了包含96个原子的2 × 2 × 2超原胞的原子间Hellmann-Feynman力.晶格动力学计算使用声子，然后用于确定声子色散关系和态密度。利用NJOY 2012的LEAPR模块，利用计算得到的YH 2中H和Y的声子态密度，建立了H-YH 2和Y-YH 2热散射定律.对所得积分和微分散射截面的分析表明S（α，β）函数具有足够的分辨率。比较实验晶格常数，热容，非弹性中子散射谱和总散射截面测量计算值被用来验证热散射定律。
Yttrium hydride (YH 2 ) is of interest as a high temperature moderator material because of its superior ability to retain hydrogen at elevated temperatures. Thermal neutron scattering laws for hydrogen bound in yttrium hydride (H-YH 2 ) and yttrium bound in yttrium hydride (Y-YH 2 ) prepared using the ab initio approach are presented. Density functional theory, incorporating the generalized gradient approximation (GGA) for the exchange-correlation energy, is used to simulate the face-centered cubic structure of YH 2 and calculate the interatomic Hellmann-Feynman forces for a 2 × 2 × 2 supercell containing 96 atoms. Lattice dynamics calculations using PHONON are then used to determine the phonon dispersion relations and density of states. The calculated phonon density of states for H and Y in YH 2 are used to prepare H-YH 2 and Y-YH 2 thermal scattering laws using the LEAPR module of NJOY2012. Analysis of the resulting integral and differential scattering cross sections demonstrates adequate resolution of the S(α,β) function. Comparison of experimental lattice constant, heat capacity, inelastic neutron scattering spectra and total scattering cross section measurements to calculated values are used to validate the thermal scattering laws.