Synthesis, characterization, and microwave dielectric properties of Ni0.5Ti0.5NbO4 ceramics through the aqueous sol-gel process

A kind of dielectric ceramic based on tetragonal rutile structure Ni0.5Ti0.5NbO4 (NTN) was prepared by the aqueous sol-gel process. The main objective was to significantly reduce the ceramic sintering temperature by sol-gel process while maintaining acceptable properties. A further objective was to optimize the three key properties-relative permittivity (epsilon(r)), quality factor (Q.f) and the temperature coefficient of resonant frequency (tau(f)). Highly reactive nanosized NTN powders with particle sizes of 20-50 nm were successfully obtained at 800 degrees C as precursors. Sintering characteristics and microwave dielectric properties of Ni0.5Ti0.5NbO4 ceramics were studied depending on sintering temperatures ranging from 850 degrees C to 1200 degrees C. The excellent microwave properties of Ni0.5Ti0.5NbO4 (NTN) ceramic was found at 1100 degrees C with epsilon(r) = 59.95, Q.f = 15,094 GHz, tau(f) = 111.15 ppm/degrees C. The lower sintering temperatures and excellent microwave dielectric properties would make these ceramics promising for application in microwave components. (C) 2015 Elsevier B.V. All rights reserved.