Improved Densification and Microwave Dielectric Properties of BaO·Nd₂O₃·5TiO₂Modified with an Iso-Component Borate Glass

Abstract

BaO·Nd 2 O 3 ·5TiO 2 (BNT) ceramics modified with a borate glass containing Ba, Nd and Ti as glass constituents were investigated with regard to their sintering behavior and microwave dielectric properties. An addition of iso-component glass significantly improved the sinterabilty of the BNT ceramics and lowered the sintering temperature. A maximum density of 5.29 g/cm 3 and an x-y shrinkage of 17% were obtained for BNT ceramics containing 10wt.% of the glass sintered at 1100 o C. The dielectric composition without the glass additive was only slightly densified at 1100 o C. The resulting sample exhibited two crystalline phases, BaNd 2 Ti 5 O 1 4 and Ba 2 Ti 9 O 2 0 , regardless of sintering temperature and glass content. When >10wt.% glass was added, exaggerated grain growth with a less uniform microstructure was found, resulting in the subsequent reduction of the fired density and the dielectric properties. BNT ceramics containing 10wt.% of the isocomponent glass sintered at 1100 o C for 4 h showed promising dielectric properties of k = 71.3 and Q = 1,330.