Dielectric Properties of Glasses in the Systems Composed of Tellurite (TeO<sub>2</sub>) and Some Phosphates

Abstract

The crystal structure of tellurite (TeO2) is similar to that of titanium dioxide which has high dielectric constant. TeO2-containing glasses which have antisymmetrical (TeO6) octahedra, as in the case of tellurite, show peculiar dielectric properties, namely, high dielectric constants and low dielectric losses. According to an experiment by Stanworth, however, thermal expansion of these glasses is very large, softening temperature or mechanical strength are low, and chemical durability is poor. In this paper, results are reported on experiments to improve electrical and mechanical properties by finding new glass forming regions in the system TeO2-Ba(PO3)2-RPO3(R=Li, Na, K). Rather stable glasses were obtained. Physical properties and chemical durability were considerably satisfactory except for glasses of high potassium content. At a room temperature dielectric constant and dielectric loss for 1Mc/sec is 15-26 and 0.002-0.008 respectively. Thermal expansion coefficients are 120-166×10-7/°C (from room temperature to 200°C) and softening temperatures are 380°C-430°C. Relations between dielectric properties and glass structure are discussed.