Ternary Hydrides Possessing the Cubic Perovskite Structure. I. A Neutron-Diffraction Study of BaLiH3 and BaLiD3

Abstract

Neutron‐diffraction studies on powered samples of BaLiH₃ and BaLiD₃ have shown that the structure is of the inverted perovskite type with the atomic positions of space group $\mathrm{P}\text{m3m}$ : Ba in (0, 0, 0), Li in $(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ , and H or D in $(\frac{1}{2},\frac{1}{2}\text{, 0; 0,}\frac{1}{2},\frac{1}{2};\frac{1}{2}\text{, 0,}\frac{1}{2})$ . The SrLiH₃ and EuLiH₃ are presumably isostructural. The lattice parameter for BaLiH₃ is 4.023 ± 0.001 Å and slightly smaller for BaLiD₃. The total neutronscattering cross section for hydrogen is $\text{30\hspace{0.17em}±\hspace{0.17em}2 b}$ , a rather low value compared to other hydrogen‐containing compounds, but comparable to that observed in other hydrides.