%0 Journal Article
%T Covalent Si¨CH Bonds in the Zintl Phase Hydride CaSiH1+x (x ¡Ü 1/3)£¿
%J Inorganics | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/inorganics7090106
%X The crystal structure of the Zintl phase hydride CaSiH ¡Ö4/3 was discussed controversially, especially with respect to the nature of the silicon-hydrogen interaction. We have applied X-ray and neutron powder diffraction as well as total neutron scattering on a deuterated sample, CaSiD 1.1. Rietveld refinement (CaSiD 1.1, Pnma, a = 14.579(4) £¿, b = 3.8119(4) £¿, c = 11.209(2) £¿) and an analysis of the neutron pair distribution function show a silicon-deuterium bond length of 1.53 £¿. The Si¨CH bond may thus be categorized as covalent and the main structural features described by a limiting ionic formula Ca 2+H £¿(Si £¿) 2/3(SiH £¿) 1/3. Hydrogen atoms decorating the ribbon-like silicon polyanion made of three connected zigzag chains are under-occupied, resulting in a composition CaSiH 1.1. Hydrogen-poor Zintl phase hydrides CaSiH <1 with hydride ions in Ca 4 tetrahedra only were found in an in situ neutron diffraction experiment at elevated temperature. Hydrogen (deuterium) uptake and release in CaSiD x (0.05 ¡Ü x ¡Ü 0.17) is a very fast process and takes less than 1 min to complete, which is of importance for possible hydrogen storage applications. View Full-Tex
%U https://www.mdpi.com/2304-6740/7/9/106