Preparation of Proton Conductive Crystallized Tin Phosphate Glasses by Hydrothermal Treatments

Abstract

Phosphate glasses are known to show proton conductivity, because they contain a significant amount of non‐bridging oxygen and can contain water molecules. However, glasses prepared by the melting method have low‐water content, resulting in very low‐electrical conductivity (10−9–10−11 S cm). Hydrothermal treatment using an autoclave is useful to increase the proton content in glass obtained by the melting method and improve electrical conductivity. In this work, tin phosphate glasses are treated by hydrothermal conditions, and their electrical conductivity is investigated. After the hydrothermal treatment, the glasses change from transparent to white. The glasses are shown to be crystallized SnHPO4, Sn2(OH)PO4, and Sn2P2O7 by XRD. The formation of the crystals is occurred when the samples treated at 75 °C for 60 min, and the crystals are grown with increase of treatment time. The formation of these crystals causes the conductivity of the glasses to increase to 10−4 S cm when the glass is treated at 75 °C for 90 min.