Structures, phase transformations, and dielectric properties of Bi2(Zn1−xMgx)2/3Nb4/3O7 pyrochlore ceramics as temperature stable LTCC material

Abstract

As a candidate of thermostable LTCC material, Bi2(Zn1−xMgx)2/3Nb4/3O7 (0.0⩽x⩽1.0) ceramics with improved dielectric properties have been prepared via conventional mixed oxide route. The relations of phase equilibrium, crystal structure and dielectric properties of the composites were investigated systematically. A monoclinic – [ monoclinic+cubic ] – cubic phase transition occurred with the increasing Mg2+ content. The phase boundaries located around x=0.3 and x=0.7 for monoclinic and cubic phases, respectively. Near-zero temperature coefficient of permittivity was obtained and the permittivity was improved from 80 to 200 in this system, which were strongly correlated with phase composition. The Bi2(Zn1−xMgx)2/3Nb4/3O7 ceramic with x=0.5 satisfied the EIA specification NP0 exhibited excellent dielectric properties of k′=98, tanδ=3.4×10−4, τk=0.65ppm/°C with the low-firing temperature of 900°C within the two-phase region, which can be a promising candidate for low temperature co-fired ceramics (LTCC) and multilayer components applications in high frequency and microwave range.