Synthesis, structure and properties of solid solutions Ва1–хSn1+хF4 and (KyВа1–y)(1–х)Sn1+хF4–y(1–х)

Abstract

We investigated the structure and electric conductivity of solid solutions of homovalent substitution Ва1–хSn1+хF4 (where х=0.03, 0.05, 0.07, 0.10, 0.15 and 0.23) and heterovalent substitution (KyВа1–y)(1–х)Sn1+хF4–y(1–х) (where х=0.03, 0.05, 0.10 and у=0.03, 0.05, 0.10) with the structure of BaSnF4. It was been found that the substitution of 7 mol.% of Ba2+ cations by Sn2+ cations contributed to an increases in electrical conductivity. The solid solution Ba0.77Sn1.23F4 had the highest electrical conductivity (573=6.8010–3 S cm–1). The substitution of barium ions by potassium ions in the BaSnF4 crystal lattice allowed reducing the conductivity of solid solutions regardless of the substituent content. Only the phases containing more than 3 mol.% of K+ ions exhibited the conductivity which exceeded the value of the initial phase at the temperatures above 385 K. In fluoride-conducting phases (KyBa1–y)(1–x)Sn1+xF4–y(1–х), the following solid solutions showed the highest electrical conductivity: (K0.05Ba0.95)0.97Sn1.03F3.95 (573=6.7810–4 S сm–1), (K0.03Ba0.97)0.95Sn1.05F3.97 (573=1.0010–3 S сm–1) and (K0.10Ba0.90)0.90Sn1.10F3.91 (573=8.7010–3 S сm–1).