Anisotropic Effects of Bromine Substitution in Betaine Calcium Chloride Dihydrate

摘要

The effects of partial substitution of chlorine by bromine in incommensurate betaine calcium chloride di-hydrate (BCCD) have been investigated by FTIR reflectivity and elastic neutron scattering. Bromine distorts the H-bonds linking the Ca complexes and induces local symmetry breaking. The temperature dependence of b and c lattice parameters of the 4 percent and 8 percent brominated compounds reveals that this distortion has effects that are markedly anisotropic. This anisotropy may help to clarify why bromine progressively destabilizes the low temperature phases of BCCD.