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, Bi-2(Zn1-xNix)(2/3)Nb4/3O7 (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 (beta-BZN) to cubic phase (alpha-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 degrees C. The temperature coefficient of dielectric constant is controlled by phase composition and is found to be -6.4 ppm/degrees C at the two-phase coexistence region of the doping content x = 0.35. The dielectric properties of epsilon = 101.2, tan delta = 9.5 x 10(-4) are obtained in this component. The features of the Bi-2(Zn1-xNix)(2/3)Nb4/3O7 ceramics make them promising for use in high-frequency applications. (c) 2018 Published by Elsevier B.V.