Abstract
A novel NaAgMoO4 material with spinel-like structure was synthesized by using the solid state reaction method and the ceramic sample was well densified at an extreme low sintering temperature about 400°C. Rietveld refinement of the crystal structure was performed using FULLPROF program and the cell parameters are a = b = c = 9.22039 Å with a space group F D −3 M (227). High performance microwave dielectric properties, with a permittivity ~7.9, a Qf value ~33,000 GHz and a temperature coefficient of resonant frequency ~−120 ppm/°C, were obtained. From X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS) analysis of the co-fired sample, it was found that the NaAgMoO4 ceramic is chemically compatible with both silver and aluminum at the sintering temperature and this makes it a promising candidate for the ultra-low temperature co-fired ceramics technology. Analysis of infrared and THz spectra indicated that dielectric polarizability at microwave region of the NaAgMoO4 ceramic was equally contributed by ionic displasive and electronic polarizations. Its small microwave dielectric permittivity can also be explained well by the Shannon's additive rule.
Highlights
From XRD and EDS analysis of the co-fired sample, it was found that the NaAgMoO4 ceramic is chemically compatible with both silver and aluminum at the sintering temperature and this makes it a candidate for the ultra-low temperature cofired ceramics technology
Its densification temperature is almost half of that of the most popular low-fired Al2O3 material with glass addition and it might be promising in the dielectric substrate application
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Summary
Correspondence and requests for materials should be addressed to Z.D. Low temperature co-fired ceramic (LTCC) technology has played an important role in the fabrication of modern electronic devices[3,4]. Advantage of this technology is that the green tape, consisting of inorganic powders and organic materials, is soft and easy to be processed layer by layer separately in the meantime, and passive components can be integrated within a monolithic bulk module with IC chips mounted on the surface. The most popular method to lower sintering temperature of dielectric ceramic with high microwave dielectric performance is the addition of glass or low melting point oxides (B2O3 based, SiO2 based etc.)[3]. It is seen that as sintering temperature was increased from 350uC to 380uC, bulk density of the NaAgMoO4 ceramic increased from
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