Effect of 1 wt% CoO addition on dielectric and microstructural behaviour of (SrO·TiO₂)-(2SiO₂·B₂O₃) glass and glass ceramic

Abstract

Glass of the nominal composition 64 wt%(SrO·TiO₂)·35 wt%(2SiO₂·B₂O₃)-1 wt%(CoO) was prepared. The glass samples were subjected to heat treatment at 900 and 950 C. The phase progression in these glass ceramics from X-ray diffraction studies shows the formation of Sr₂B₂O₅ as primary crystalline phase followed by rutile (TiO₂), Sr₃Ti₂O₇, SrB₂Si₂O₈ and Sr₃B₂SiO₈ as secondary phases. The first DTA exothermic peak of glass corresponds to the crystallization of Sr₂B₂O₅, rutile and Sr₃Ti₂O₇ phase while second crystallization peak may be assigned to the formation of SrB₂Si₂O₈ and Sr₃B₂SiO₈ phases. From microstructure studies we find that strontium borate grows with larger grain size whereas the other phases like Sr₃Ti₂O₇, TiO₂ appear smaller in size. Cobalt oxide content in the strontium titanate borosilicate glass ceramic gives the thermal stability to dielectric behaviour and decreases the dielectric loss.