Dielectric Properties of Low-Firing Bi_2Mo_2O_9 Thick Films Screen Printed on Al Foils and Alumina Substrates

摘要

Low-firing Bi_2Mo_2O_9 thick films with a thickness of 15-20 μm were screen printed on Al foils and alumina substrates by screen-printing technology. The phase evolution, morphologies, and dielectric properties of the thick films were investigated. The thick films showed a pure Bi_2Mo_2O_9 phase at temperatures below 610℃. A mixture of Bi_2MoO_6, Bi_2Mo_3O_(12), and Bi_2Mo_2O_9 phases was found in the thick films sintered at 610 ℃ and higher temperatures. The Bi_2Mo_2O_9 thick films on Al foils sintered at 645℃ showed excellent dielectric properties with a relative permittivity of 38 and a dielectric loss of 0.7% at 5 MHz. At the microwave frequency range from 5 to 19 GHz, the Bi_2Mo_2O_9 thick films on alumina substrates sintered at 645 C had a relative permittivity of ～35 and Q ×f of ～ 12500 GHz. It indicates that the Bi_2Mo_2O_9 composition as potentially useful for low-temperature cofired ceramic using Al electrode.