Effect of Co-substitution on microwave dielectric properties of Li3(Mg1−xCox)2NbO6 (0.00 ≤ x ≤ 0.10) ceramics

- Co-Substitution increased the Q·ƒ values of Li3Mg2NbO6 ceramics to 127,600 GHz.
- Substitution of Mg2+ improved the τf values of ZnZrNb2O8 ceramics.
- Excellent microwave dielectric properties were obtained when x = 0.02.

The Li3(Mg1−xCox)2NbO6 (0.00 ≤ x ≤ 0.10) ceramics were prepared by the solid-state reaction route in this paper. The effects of Co-substitution on phase composition, microstructure and microwave dielectric properties of the Li3Mg2NbO6 were investigated by a variety of characterization methods. XRD patterns and Raman spectrum revealed that the all the compositions possessed orthorhombic structure with the space group of Fddd. The Q·f values of samples sintered at 1300 °C increased from 91,600 GHz at x = 0 to 127,600 GHz at x = 0.02, which was basically attributed to the appropriate amount of Co2+. With the x value increasing from 0 to 0.10, the τf value was gradually shifted toward zero, which indicated that the ionic substitution could effectively adjust the crystal stability of the matrix. In addition, there were no significant changes in the dielectric constant and grain sizes in the Li3(Mg1−xCox)2NbO6 compositions. Out these compositions, the Li3(Mg0.98Co0.02)2NbO6 ceramic sintered at 1300 °C exhibited excellent microwave dielectric properties of ɛr = 15.22, Q×f = 127,600 GHz and τf = −3.64 ppm/°C, which made the ceramics promising for future applications.

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