Synthesis, Structure, and Heat Capacity of Some Basic Hydroxohalide Glasses of Zirconium and Hafnium

This work highlights the synthesis and properties of
novel basic
hydroxohalide glasses of zirconium and hafnium. The hydroxohalide
glasses are M­(OH)4−αXα·(n)­H2O where M represents either zirconium or hafnium, and X represents
either chloride or bromide. The chemical structure is investigated
using X-ray diffraction, total scattering, and the pair distribution
function method to identify the local structure and any short-range
connectivity. The thermodynamic properties of the glasses are probed
using low-temperature heat capacity, where a gap in the phonon density
of states is discussed and related to boson peaks in the heat capacity
of the glasses. These results represent the first published synthesis
and thermodynamic properties of zirconium and hafnium basic hydroxohalide
glasses. Synthesis methods, structural determination, and analysis
of the heat capacity data allow for a comprehensive look at the makeup
and unique properties of these novel glassy materials. Values of the
standard thermodynamic functions Cp,m°, Δ0TSm°, Δ0THm°, and Φm° are also reported.