Dependence of microwave dielectric properties on the substitution of isovalent composite ion for Nb-site of MgZrNb2−x(Sn1/2W1/2)xO8 (0 ≤ x ≤ 0.15) ceramics
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MgZrNb2−x(Sn1/2W1/2)xO8 (0 ≤ x ≤ 0.15) dielectric ceramics were synthesized through solid state reaction route. SnO2, WO3 and Nb2O5 were pre-calcined to promote the substitution element to fully enter the Nb-site when reacting with MgO and ZrO2. The formation of solid solutions with monoclinic wolframite structure were confirmed. Rietveld refinement and P–V–L theory were used as intrinsic factors of analyzing the changes in microwave dielectric properties. With the increase of (Sn1/2W1/2)5+ substitution amount, εr of highly densified MgZrNb2−x(Sn1/2W1/2)xO8 ceramic decreased slowly, which was mainly ascribed to low bond iconicity. The optimal substitution of isovalent composite ions enhances the total lattice energy, leading to an increase in Q × f value. The increase of τf was closely correlated with the decrease of the total bond energy. When x = 0.06, the optimal dielectric properties, εr= 24.61, Q × f = 93346.3 GHz, τf= − 48.46 ppm/°C, were successfully obtained for the MgZrNb2−x(Sn1/2W1/2)xO8 specimens sintered at 1300 °C.
This work was supported by the National Natural Science Foundation of China (No. 51877146).
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