Microwave dielectric properties of low firing temperature stable scheelite structured (Ca,Bi)(Mo,V)O ₄ solid solution ceramics for LTCC applications

In the present work, a systematic study on microwave properties of Ca _1-x Bi _x Mo _1-x V _x O ₄ (0.2 ≤ x ≤ 0.5) solid solution ceramics synthesized by using the traditional solid-state reaction method was conducted. A scheelite structured solid solution was formed in the composition range 0.2 ≤ x ≤ 0.5. We successfully prepared a microwave dielectric ceramic Ca _0.66 Bi _0.34 Mo _0.66 V _0.34 O ₄ with a temperature coefficient of resonant frequency (TCF) near to zero and a low sintering temperature by using (Bi, V) substituted (Ca, Mo) in CaMoO ₄ to form a solid solution. The Ca _0.66 Bi _0.34 Mo _0.66 V _0.34 O ₄ ceramic can be well sintered at only 870 °C and exhibits good microwave dielectric properties with a permittivity (ε _r ) ˜21.9, a Qf ˜18,150 GHz (at 7.2 GHz) (Q = quality factor = 1/dielectric loss; f = resonant frequency), a TCF ˜ + 0.1 ppm/°C. The chemical compatibility with silver indicated that the Ca _0.66 Bi _0.34 Mo _0.66 V _0.34 O ₄ ceramic might be a good candidate for the LTCC applications.