Temperature-stable dielectrics based on Ni-doped Bi2Zn2/3Nb4/3O7 pyrochlore ceramics for low temperature co-fired ceramic

As an admirable candidate of thermostable LTCC materials, Bi2(Zn1-xNix)2/3Nb4/3O7 (0.0 ≤ x ≤ 0.5) ceramics with improved dielectric properties have been prepared via conventional mixed oxide route. Microstructure analysis manifests that the phase transition occurs from monoclinic zirconolite phase (β-BZN) to cubic phase (α-BZN) for Ni doped specimens. The crystal field theory supported the analysis of the initial phase transition processes. From the structure transformation and electrical properties test result, the Ni2+ substituted Zn2+ shows an effective method to restrain the grain growth and improve dielectric constant when sintered at 925 °C. The temperature coefficient of dielectric constant is controlled by phase composition and is found to be −6.4 ppm/°C at the two-phase coexistence region of the doping content x = 0.35. The dielectric properties of ε = 101.2, tanδ = 9.5 × 10−4 are obtained in this component. The features of the Bi2(Zn1-xNix)2/3Nb4/3O7 ceramics make them promising for use in high-frequency applications.