Effect of Divalent Dopants on the Properties of Ba_3.75Nd_9.5Ti₁₈O₅₄ Microwave Dielectric Resonators

Pellets in the ternary solid-solution Ba 6_3xNd8+2xTi18O 54 (x=0.75) have been processed to near theoretical density by mixed-oxide synthesis, and their dielectric properties determined to be Er,89, Qf>10,000, and tf-+60ppmf C at microwave frequencies. Similar ceramics with Ca, Sr, and Pb partially substituted for Ba were also processed and analysed. Both Ca and Sr were found to increase Er to 100-105 but significantly lower Qf and inflate tf. While Pb substitution also lowered Qf, it had no significant effect on Er and beneficially suppressed tf to values from -16 to +8ppm/°C, tunable with Pb content, strongly suggesting that these materials may be useful for commercial applications.