Inelastic neutron scattering from the alkali metal borohydrides and calcium borohydride

Abstract

This paper reports a study of the librational modes of the borohydride, BH^–₄, ion in the alkali metal borohydrides and in calcium borohydrides. Values for sodium borohydride have previously been inferred from specific heat data but values of the librational frequencies in these salts have not previously been determined directly. In the case of caesium borohydride, which can be cooled to liquid nitrogen temperatures without undergoing a phase transition, the frequency of the librational mode increases on cooling and its breadth decreases dramatically.