Phase transition and microwave dielectric properties of LiY(W1−xTex)2O8 (0.0 ≤ x ≤ 0.2)

The phase transition and microwave dielectric properties of LiY(W1−xTex)2O8 ceramics (0.0 ≤ x ≤ 0.2) were investigated in this paper. X-ray diffraction (XRD) results show that there is phase transition from wolframite to scheelite structure due to Te6+ substitution for W6+. The phase of LiY(W1−xTex)2O8 changed from wolframite to scheelite structure completely for the x ≥ 0.1 compositions after sintering at 875 °C/2 h. The dielectric constant and Q × f value decrease with the increase of x when x ≥ 0.05. The temperature coefficient of resonant frequency (τf) changed from positive values into negative values with the increase in x value. Among the compositions examined, those with x = 0.2 sintered at 850 °C/2 h had the best dielectric properties, including ɛr = 14.3, Q × f = 4042 GHz, and τf = −6.05 ppm °C−1.