Crystallization behavior of new transparent glass-ceramics based on barium borate glasses

This paper describes the preparation of several new transparent and very fine crystal glass-ceramics from the BaO-B2O3 system utilizing an appropriate additive of fluorides, partial replacement of B2O3 by SiO2, and introducing nucleating agents, such as TiO2. The physical properties of the prepared materials and the changes with varying base glass compositions and heat treatment programs were investigated. The thermal behavior and microstructure of the developed phases were characterized using DTA, XRD, and SEM. Glass-ceramics with marked transparency were prepared. These transparent derivatives owe their transparency to the distinctive properties of the nano-crystalline samples. The dielectric constant of transparent glass-ceramics samples at 100 kHz were between 14-20, which is very suitable for a wide range of applications, such as the highspeed switching of large-scale integrators. It was found that the addition of F- and SiO2 greatly influenced the transparency of the produced glass-ceramics. Also, the addition of TiO2 greatly enhanced transparency, in spite of increasing cutoff in the UV region to a higher wavelength. (C) 2008 The Ceramic Society of Japan. All rights reserved.