We report results on the configuration and vibrational dynamics of hydride ions (H^–) in the novel mixed-anion, nitride-hydride, catalyst Ca₃CrN₃H by means of variable temperature inelastic neutron scattering experiments, harmonic phonon calculations, and machine-learning molecular dynamics calculations. The combined analyses of experimental and theoretical data show that the vibrational dynamics of H^– are manifested as a broad, asymmetric vibrational band between 80 and 130 meV. These vibrational dynamics are generally anharmonic in nature and polarized along the crystallographic c axis, and their dispersive character reveals significant interactions between neighboring H^– in the material. We find that most H^– are surrounded by two other H^– and that the H^– sites of the studied sample have an occupancy of at least 95%. We argue that this high H^– occupancy may be related to the material’s high efficiency as a catalyst for ammonia synthesis.

中文翻译：

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氮化物氢化物催化剂 Ca3CrN3H 中氢离子的构型和动力学


我们通过变温非弹性中子散射实验、谐波声子计算和机器学习分子动力学计算，报告了新型混合阴离子、氮化物氢化物催化剂 Ca₃CrN₃H 中氢离子 （H^–） 的构型和振动动力学结果。实验和理论数据的综合分析表明，H^– 的振动动力学表现为 80 至 130 meV 之间的宽而不对称振动带。这些振动动力学本质上通常是非谐的，并沿晶体学 c 轴极化，它们的色散特性揭示了材料中相邻 H^– 之间的显着相互作用。我们发现大多数 H^– 被另外两个 H^– 包围，并且研究样本的 H^– 位点的占用率至少为 95%。我们认为，这种高 H^– 占用率可能与该材料作为氨合成催化剂的高效率有关。