Effect of Vanadium Content on the Microwave Dielectric Properties of Sr 2 V x O 7 (1.80 ≤ x ≤ 2.05) Ceramics

Vanadium content has a prominent effect on the microwave dielectric properties of Sr2VxO7 (1.80 ≤ x ≤ 2.05) ceramics, which is related to extrinsic factors and intrinsic factors, such as secondary phase, bulk density, crystal structure, and V–O bond length. Rietveld refinement, energy dispersive spectroscopy, and Raman spectra analysis revealed that an appropriate vanadium deficiency causes the appearance of secondary phase Sr3V2O8, which results in the variation of unit cell volume and the significant improvement of Q × f value and the temperature coefficient of resonant frequency. Specifically, the Sr2V1.90O7 ceramic sintered at 950°C possesses optimum microwave dielectric performances: the dielectric constant of 11.1, the Q × f value of 36,500 GHz, and the temperature coefficient of resonant frequency of − 35.6 ppm/°C.