Abstract:MgxZn1.8-xSiO3.8(x=0, 0.1, 0.2, 0.3, 0.4) microwave ceramics with willemite structure were prepared by the traditional solid-phase synthesis method. The effect of Mg on crystal structure, microstructure and dielectric properties of MgxZn1.8-xSiO3.8-x ceramics were characterized on the basis of X-ray diffraction, raman spectroscopy, and scanning electron microscopy and vector network analyzer. The results show that the theoretical polarizability of MgxZn1.8-xSiO3.8 microwave ceramics decreases, and the relative permittivity decreases correspondingly with the increase of doping Mg amount x of sintering temperature at 1 300 ℃. With the increase of x, the average twist of oxygen tetrahedron decreases first and then increases, resulting in the temperature coefficient of resonant frequency decreasing first and then increasing. With the increase of doping amount, the symmetry of the six-membered ring composed of Zn(1)/Mg(1)O4, Zn(2)/Mg(2)O4, and SiO4 tetrahedra increases, while the Zn(Mg)—O bond length decreases and the bond energy increases, resulting in the quality factor Q×f increases. Mg0.4Zn1.4SiO3.8 ceramicshave excellent properties, the relative permittivity εr is about 6.2, the Q×f is about 112 100 GHz, and the resonant frequency temperature coefficient τf is about -19.2×10-6 ℃.
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