CO-SUBSTITUTION EFFECTS OF Eu3+/Dy3+ ON Na+ CONDUCTION PROPERTIES OF Na5YSi4O12-TYPE PHOSPHOSILICATES GLASS-CERAMICS OF Na4Y0.6-2zEuzDyzP0.2Si2.8O9

Abstract

In the present study, Eu³⁺/Dy³⁺-co-introduced glasses and fully crystallized glass-ceramics were prepared by partially substitution of Y³⁺ with Eu³⁺ and Dy³⁺ in the composition of Na₄Y_0.6-2zEu_zDy_zP_0.2Si_2.8O₉. By varying the amount of [Eu³⁺ + Dy³⁺] added to those glasses and crystallized glass-ceramics, we evaluated the co-substitution effect on the conduction properties of the glass-ceramics. The added amount of [Eu³⁺ + Dy³⁺] = 0.2 gave the highest conductivity of the Na₅YSi₄O₁₂-type family of Na₄Y_0.6-2zEu_zDy_zP_0.2Si_2.8O₉ as 7×10^-2 and 1.1 S cm^-1 for grains and grain boundaries at 300°C, respectively.