Glass-Free CuMoO4 Ceramic with Excellent Dielectric and Thermal Properties for Ultralow Temperature Cofired Ceramic Applications

A new glass-free low temperature sinterable CuMoO4 ceramic was prepared by a solid state ceramic route. The structural, microstructural, electron dispersive spectrum, and X-ray photoelectron spectroscopy analysis revealed the quality of the material synthesized. The CuMoO4 ceramic sintered at 650 degrees C exhibits densification of 96% and low coefficient of thermal expansion (CTE) of 4.6 ppm/degrees C in the temperature range of 25-500 degrees C. It has relative permittivity (epsilon(r)) of 7.9, quality factor (Qf) of 53 000 GHz, and temperature coefficient of resonant frequency (tau(r)) of -36 ppm/degrees C (25-85 degrees C) at 12.7 GHz. The sintered ceramic also shows epsilon(r) of 11 and low dielectric loss (tan delta) of 2.7 x 10(-4) at the frequency of 1 MHz. The full width half-maximum (fwhm) of A(1g) Raman mode of CuMoO4 ceramic at different sintering temperatures correlate well with the Qf values. The low sintering temperature, low relative permittivity, high-quality factor, and matching coefficient of thermal expansion to that of Si make CuMoO4 a suitable candidate for ultralow temperature cofired ceramic (ULTCC) applications.