Synthesis and crystal structure of β-AlD3

β-AlD3 was synthesized from LiAlD4 and AlCl3 via thermal decomposition of aluminum hydride etherate in presence of LiBH4 and excess LiAlD4. β-AlD3 was determined by powder neutron diffraction and synchrotron X-ray diffraction to take the pyrochlore structure and it crystallizes in space group Fd3¯m. The cubic structure has unit-cell dimension a = 9.0037(1) Å and consists of corner-sharing AlD6 octahedra where each hydrogen is shared between two octahedra. Each of the six octahedra surrounding an octahedron is interconnected to two of the other surrounding octahedra. The octahedra are forming a 3D network with about 3.9 Å channels. There is one Al and one D crystallographic site and the Al-D distance is 1.712(1) Å.