Principle of equivalence of the disorder sources and heat conductivity of solids

The correlation between chemical composition and heat conductivity of fluoride materials, including glasses and anti-glasses (heterovalent solid solutions with variable amount of ions in the unit cells), obeys Tretyakov’s principle of equivalency of the disorder sources. Increase of the rare earth element content in M$_{1-x}$R$_{x}$F$_{2+x}$ (M = Ca, Sr, Ba; R = La–Lu, Y) solid solutions results in a sharp decline of their heat conductivity as well as alters the temperature dependency of the latter parameter. Heat conductivity of M$_{1-x}$R$_{x}$F$_{2+x}$, instead of going through its maximum at lower temperature (as it should be for the typical crystalline materials), becomes monotoneous as for glasses. Methods controlling the heat conductivity of the novel materials have been discussed.