Fabrication of low-temperature co-fired ceramic (LTCC) densified at a low sintering temperature (<900 °C) is energy saving and environmentally friendly. Here, an interesting attempt has been made to lower the sintering temperature of MgGa2O4 by adding CuMoO4 for LTCC application. The sintering temperature of MgGa2O4 was remarkably reduced from 1410 to 900 °C, which contributed to energy saving. Furthermore, a series of studies on microstructure, sintering behavior, lattice parameters, and microwave dielectric characteristic of the samples were carried out. The occurrence of ion substitution between MgGa2O4 and CuMoO4, which affected the sintering densification, ionic polarizability, and Mg–O bond length, made the composites present various sintering and dielectric properties. Moreover, the full width half maximum (FWHM) value of the T2g peak in Raman spectra and lattice distortion were also analyzed to reveal the intrinsic interaction between structure and dielectric properties. Finally, the 0.5MgGa2O4–0.5CuMoO4 ceramics sintered at 900 °C showed the best comprehensive performance, εr = 6.8, Q × f = 15,800 GHz, τf = −54.2 ppm/°C. These promising properties make the composite more suitable for practical application.
This study optimizes the temperature coefficient of resonant frequency (τ f ) in CuMoO 4 ceramics from −36 to −8.82 ppm/°C through W 6+ B-site substitution. XRD analysis confirms the single-phase structure of CuMo 1- x W x O 4 ceramics, while Rietveld refinements reveal an expansion in lattice parameters. W 6+ substitution slightly reduces the relative permittivity (ε r ) due to the changes in sintering density and ion polarizability. Moreover, the internal effects of W 6+ substitution on the Q×f value are systematically investigated by analyzing the Raman peak's full width at half maximum (FWHM) and conducting packing fraction calculations. Additionally, lattice distortion and bond valence analyses elucidate the intrinsic mechanism behind τ f improvement. Consequently, when x = 0.08, CuMo 1- x W x O 4 sintered at 625°C exhibits superior overall performance: ε r = 5.13, Q×f = 65,506 GHz, τ f = −8.82 ppm/°C. Furthermore, it demonstrates good chemical compatibility with Al electrodes making the material more suitable for ULTCC practical applications.
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