Dependence of microwave dielectric properties on site substitution in Ba3.75Nd9.5Ti18O54 ceramic

Abstract

Microwave dielectric properties of Ba3.75(Nd1−x Sm x )9.5Ti18−z Al4z/3O54 (0 ≤ x ≤ 0.4, 0 ≤ z ≤ 0.9) ceramic have been determined in this study. All samples showed a single tungsten-bronze like structure. Albeit dielectric constant was degraded by aluminum doping, the quality factor improved by 20 % and the temperature coefficient of resonant frequency decreased by 60 %. Based on this result, samarium replacement was implemented and improved microwave properties, including relative permittivity higher than 80, quality factor around 10,000 GHz and temperature coefficient of resonant frequency at the vicinity of zero, can be obtained. At last, with appropriate site-substitution content control (x = 0.2, z = 0.6), we gained a ceramic, with dielectric constant of 81, quality factor of 8650 GHz and temperature coefficient of resonant frequency of +3.8 ppm/°C, that possesses the potentials for radio frequency identification applications.