DOE OSTI2020
RbNa3H4 is Caswellsilverite-like structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Rb1+ is bonded to six H1- atoms to form RbH6 octahedra that share corners with six equivalent RbH6 octahedra and edges with twelve equivalent NaH6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Rb–H bond lengths are 2.64 Å. Na1+ is bonded to six H1- atoms to form NaH6 octahedra that share corners with six equivalent NaH6 octahedra, edges with four equivalent RbH6 octahedra, and edges with eight equivalent NaH6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Na–H bond lengths are 2.64 Å. There are four inequivalent H1- sites. In the first H1- site, H1- is bonded to two equivalent Rb1+ and four equivalent Na1+ atoms to form a mixture of corner and edge-sharing HRb2Na4 octahedra. The corner-sharing octahedral tilt angles are 0°. All H–Na bond lengths are 2.64 Å. In the second H1- site, H1- is bonded to two equivalent Rb1+ and four equivalent Na1+ atoms to form a mixture of corner and edge-sharing HRb2Na4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third H1- site, H1- is bonded to two equivalent Rb1+ and four equivalent Na1+ atoms to form a mixture of corner and edge-sharing HRb2Na4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth H1- site, H1- is bonded to six equivalent Na1+ atoms to form HNa6 octahedra that share corners with six equivalent HNa6 octahedra and edges with twelve HRb2Na4 octahedra. The corner-sharing octahedral tilt angles are 0°.