Phase Equilibria in the Quasibinary Li2O center dot 2B(2)O(3)-Yb2O3 center dot B2O3 System, Assessment of Stability, and Conductivity of Solid Solutions Based on Li2O center dot 2B(2)O(3)

摘要

Using the methods of differential thermal analysis and X-ray powder diffraction, the T-x phase diagram of the Li2O center dot 2B(2)O(3)-Yb2O3 center dot B2O3 system has been constructed. Phase diagram of this system belongs to the eutectic type and is characterized by the formation of limited Li2O center dot 2B(2)O(3)-based solid solutions. The region of limited (1 - x)Li2O center dot B2O3-xYb(2)O(3)center dot B2O3 solid solutions at 298-1038 K is x = 0-0.1 mole fraction of Yb2O3 center dot B2O3 (or alpha-Li2O center dot 2B(2)O(3)). Eutectic coordinates: 1038 K and similar to 17 mol % Yb2O3 center dot B2O3. Depending on the thermal history, (1 - x)Li2O center dot 2B(2)O(3)-xYb(2)O(3)center dot B2O3 (x = 0-0.1) solid solutions are formed both in the form of polycrystals (annealed) and in the form of amorphous glasses (quenched). Glassy and polycrystalline samples of solid solutions alpha-Li2O center dot 2B(2)O(3) (x = 0, 0.05, and 0.1) were synthesized and their physico-chemical properties were studied. The temperature dependence of the standard Gibbs energy of the reaction of formation of solid solutions is estimated (0 575 K, the conductivity of alpha-Li2O center dot 2B(2)O(3) glasses deviates from the Arrhenius equation.