Crystal Growth and Thermal Conductivity of the Congruently Melting Solid Solution Cd0.77Sr0.23F2

Abstract

Crystals of the Cd_0.77Sr_0.23F₂ solid solution (sp. gr. Fm\(\bar {3}\)m, lattice parameter a = 5.4882(1) Å), corresponding to the minimum in the liquidus and solidus curves in the CdF₂–SrF₂ phase diagram, have been grown from a melt by vertical directional solidification and their thermal conductivity has been measured in the temperature range 50–300 K. The thermal conductivity κ(T) of the Cd_0.77Sr_0.23F₂ crystals is a weak function of temperature: κ₅₀ = 1.9 W/(m K) and κ₃₀₀ = 1.5 W/(m K) at 50 and 300 K, respectively. We have carried out a comparative analysis of the thermophysical properties of congruently melting M_{1 −x}Sr_xF₂ (M = Cd, Ca, Ba) crystals with the fluorite structure, containing SrF₂ as a common component. The κ₃₀₀ of the Cd_0.77Sr_0.23F₂ crystals is lower than that of Ba_0.66Sr_0.34F₂ and Ca_0.59Sr_0.41F₂ by a factor of 2.1 and 2.7, respectively.