Sintering behavior and microwave dielectric properties of nano zinc niobate powder

Nanosized ZnNb2O6 powders obtained by high energy ball milling (HEBM) and subsequent heat treatment were compacted and sintered into near full density ceramics using pressureless sintering. The prepared ceramic samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and microwave dielectrical property measurements. All samples prepared at sintering temperatures ranging from 975 to 1100 °C, exhibit a single columbite phase and their relative densities range from ~87% to ~99%. The variation trend of permittivity and Q×f value was in accordance with variation trend of relative density. Pure columbite ZnNb2O6 ceramic sintered at 1050 °C for 5 h exhibited good microwave dielectric properties with a permittivity about 23.6, Q×f value about 72,357 GHz, and temperature coefficient of resonant frequency about −67.72 ppm/°C.