The influence of Ta2O5 additions on the thermal properties and crystallization kinetics of a lithium zinc silicate glass

The lithium zinc silicate glass exhibits two crystallization exotherms corresponding to the formation of Li2ZnSiO4 and silica phases, respectively. The silica phases include tridymite and cristobalite. The influence of Ta2O5 additions on the thermal properties and non-isothermal crystallization kinetics of this glass, including nucleation rate maxima and activation energies for crystallization, has been determined by differential scanning calorimetry and X-ray diffraction. It has been found that Ta2O5 affects the crystallization behavior markedly, inhibiting the crystallization of high thermal expansion silica phases at lower concentrations, whilst at higher concentrations also suppressing crystallization of the Li2ZnSiO4 phase. At the higher concentrations, these phases are replaced by small amounts of LiTaO3 and LiTaSiO5.