Surface and bulk crystallization of some glasses from the BaO-TiO_2-B_2O_3 system

摘要

Dielectric and especially ferroelectric materials can be used in many applications such as dynamic random access memories and infrared sensors. The dielectric properties of such materials have to be improved. For this purpose several compositions in the BaO-B_2O_3-TiO_2 system have been studied. The investigated composition was BaTiO_3 with a different amount of B_2O_3 in the range 25-50 mol%. Depending on the B_2O_3 amount the melting temperatures of the investigated glasses were in the range 1100-1250 °C. The vitreous materials have been submitted to thermal treatment in order to obtain surface and bulk crystallization. The Differential Thermal Analyses (DTA) showed out the tendency of crystallization for these samples in the 600-800 °C-temperature range. For structural analyses there have been used the X-ray diffractometry. DTA analyses, electronic microscopy and atomic force microscopy on samples crystallized by controlled thermal treatments.