Crystal structure and dielectric properties of Mn-substituted Bi_(1.5)Zn_(1.0)Nb_(1.5)O_7 pyrochlore ceramics as temperature stable LTCC material

摘要

Abstract As a potentially attractive candidate of LTCC material, (Bi_(1.5)Zn_(0.5-x)Mn_x)(Zn_(0.5)Nb_(1.5))O_7 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics with improved temperature coefficient of the dielectric constant were synthesized by a conventional mixed oxide route. The relations between the microstructure and dielectric properties of the specimens were investigated systematically. Microscopic analysis showed that all the samples maintained the (Bi_(1.5)Zn_(0.5)) (Zn_(0.5)Nb_(1.5))O_7 phase. The variation of the unit cell volumes contributed to the shift of the peaks caused by the chemical substitution of ions. The temperature coefficient of the dielectric constant of (Bi_(1.5)Zn_(0.5))(Zn_(0.5)Nb_(1.5))O_7 increased remarkably by Mn~(2+) substitution, but dielectric constant varied slightly while the dielectric loss increased steadily. The (Bi_(1.5)Zn_(0.5-x)Mn_x)(Zn_(0.5)Nb_(1.5))O_7 ceramic with x = 0.5 satisfied the EIA specification NPO and exhibited excellent dielectric properties of ε_r = 132, tanδ = 2.45× 10~(-3), τ_E = -17 ppm/℃ with the low-firing temperature of 950 ℃.