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

• Effect of Mg substitution on dielectric property of Bi2(Zn2/3Nb4/3)O7 was studied.
• The solid solution limits in Bi2(Zn1−xMgx)2/3Nb4/3O7 were determined.
• A near-zero temperature coefficient of permittivity was obtained at 900 °C.
• The relationship between phase compositions and microstructure was investigated.

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, tan δ = 3.4 × 10−4, τk = 0.65 ppm/°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.