Preparation of Ferroelectric KNbO3 Based Borate Glass System

Abstract

The incorporation method was employed to produce ferroelectric glass ceramics from the K2O–Nb2O5–B2O3 glass system. The nanocrystalline potassium niobate (KNbO3) was first prepared using a simple mixed oxide method, where the B2O3 was initially mixed and then melted to form glass. The successfully produced optically transparent glass was then subjected to a heat treatment schedule for further crystallization at temperatures ranging from 500 to 650 C, which resulted in the precipitation of the KNbO3 phase, together with the K3B2Nb3O12 phase. Scanning electron microscopy (SEM) showed the presence of randomly oriented KNbO3 crystals dispersed in a continuous glass matrix. It was found that the glass ceramics subjected to the heat treatment at temperatures higher than 545 C were opaque, while the lower gave a highly transparent glass ceramics. The crystal size and crystallinity were found to increase with increasing heat treatment temperature, which in turn plays an important role in controlling the properties of the glass ceramics,including physical, optical, and dielectric properties.