Phase Relations inBa6−3xLn8+2xTi18O54(Ln = Nd & Sm) Electroceramics

Abstract

A careful, systematic investigation ofBa6−3xLn8+2xTi18O54(BLnTss) ceramics has been performed in order to understand the relationship between composition, microstructure evolution, and microwave dielectric properties. In this paper, we report the effects of composition, morphology, and sintering time on the phase relations and properties of BLnTss (Ln = Nd, Nd/Sm, Sm) ceramics. The microwave dielectric properties of the materials are reported in addition to phase characterisation and structural analysis via X-ray diffraction and field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. BLnTss,x=0.33, ceramics with high Sm content are found to experience a severe degradation of Qf and changes inτcftrending, associated with the onset of globular and needle-like grain morphology and a Ba-Ti rich phase.x=0.67ceramics with high Nd content are found to exhibit a secondary phase (Nd2Ti2O7) upon prolonged sintering which resulted in beneficial changes to Qf andτcfwithout affectingεr. Two BLnTss ceramics compositions with near-zeroτcfwere successfully synthesised with high Qf andεrvalues.