Improved Densification and Microwave Dielectric Properties of BaO·Nd2O3·5TiO2 Modified with an Iso-Component Borate Glass

[ $BaO{\cdot}Nd_2O_3{\cdot}5TiO_2$ ] (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 $1100^{\circ}C$. The dielectric composition without the glass additive was only slightly densified at $1100^{\circ}C$. The resulting sample exhibited two crystalline phases, $BaNd_2Ti_5O_{14}$ and $Ba_2Ti_9O_{20}$, 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 $1100^{\circ}C$ for 4 h showed promising dielectric properties of k = 71.3 and Q = 1,330.