Effect of Divalent Dopants on the Properties of Ba 3.75 Nd 9.5 Ti 18 O 54 Microwave Dielectric Resonators

Pellets in the ternary solid-solution Ba6–3xNd8+2xTi18O54 (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 τf≈+60ppm/°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 τf. While Pb substitution also lowered Qf, it had no significant effect on er and beneficially suppressed τf to values from -16 to +8ppm/°C, tunable with Pb content, strongly suggesting that these materials may be useful for commercial applications.