Low-temperature sintered MgWO4-CaTiO3 ceramics with near-zero temperature coefficient of resonant frequency

The phases, microstructure, composition analysis and microwave dielectric properties of (1-x)MgWO4-xCaTiO(3) ceramics with Li2CO3-4H(3)BO(3) additions prepared by solid-state reaction method have been investigated by using X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy and advantest network analyzer. The tau(f) of (1-x)MgWO4-xCaTiO(3) were dependent on phase constitutions. The microwave dielectric properties of 0.91MgWO(4)-0.09CaTiO(3) ceramics with Li2CO3-4H(3)BO(3) were characterized, the results indicated that the epsilon(r) and Q x f were associated with the sintering temperature and amount of Li2CO3-4H(3)BO(3). The sintering temperature of ceramics was reduced to 950 degrees C from 1150 degrees C and tau(f) was modified to 0 ppm/degrees C with good Q x f Addition of 5.0 wt% Li2CO3-4H(3)BO(3) in 0.91 MgWO4-0.09 CaTiO3 ceramics sintered at 950 degrees C showed excellent dielectric properties of epsilon(r) = 15.5, Q x f=20,780 GHz (f=7.1 GHz) and r(f)similar to 0 ppm/degrees C. The material has a chemical compatibility with silver, making it a very promising candidate materials for LTCC applications. (C) 2011 Elsevier Ltd. All rights reserved.