CRYSTAL STRUCTURE AND MICROWAVE DIELECTRIC PROPERTIES OF Ba_nLa_4Ti_(3+n)O_(12+3n) HOMOLOGOUS COMPOUNDS WITH HIGH DIELECTRIC CONSTANT AND HIGH QUALITY FACTOR

摘要

Homologous compound Ba_nLa_4Ti_(3+n)O_(12+3n) series are one of candidate materials for base station of telecommunications. Crystal structure of the compound with n= 1 was refined using X-ray diffraction data of the single crystal obtained. Position of Ba and La ions were determined. Resonator ceramics discs with n=0.8 to 4 synthesized were identified on the precipitated phases and measured the microwave dielectric properties. Homologous compound with n=1 has good microwave dielectric properties: epsilon_r =46, Q centre dot f= 46,000 GHz and tau_f =-11. Moreover, temperature coefficient of resonant frequency was improved to near zero: 1.3 ppm/deg C with high epsilon_r of 44 and Q centre dot f of 47,000 GHz.