The effects of Sm2O3 addition on the microstructure and the microwave diele
ctric properties of BiNbO4 ceramics ha;e been investigated. The phase trans
ition temperature (from orthorhombic to triclinic phases) of BiNbO4 ceramic
s can be lowered with Sm2O3 addition. It also decreases with increasing Sm2
O3 addition. The dielectric constant and the theoretical density are found
to increase with increasing sintering temperature, but decrease with increa
sing Sm2O3 content. The quality factor, Q, is significantly dependent on Sm
2O3 substitution, due to many factors, including the microstructure, the ph
ase transition, and the densification. The temperature coefficient of reson
ant frequency, tau (f), is correlated to the phase transition. Bi0.95Sm0.05
NbO4 ceramics, sintered at 950 degreesC, exhibits the microwave dielectric
properties epsilon (r) similar to 44.43. Q X f values similar to 1800 (at 7
.2 GHz), and tau (f) similar to -4.2 ppm/degreesC. (C) 2001 Elsevier Scienc
e Ltd. AII lights reserved.