Structure and microwave dielectric properties of La (2− x)/3 Na x(Mg 1/2W 1/2)O 3

Abstract

The structure evolution, sintering behavior and microwave dielectric properties of La (2− x)/3 Na x (Mg 1/2W 1/2)O 3 ( x = 0–0.5) were investigated in this paper. The X-ray diffraction (XRD) results show that all samples exhibit single phase, and the structure changed from orthorhombic when 0 ≤ x < 0.3 to monoclinic phase when 0.3 ≤ x ≤ 0.5. The size and ordering degree of A/B-site domains decrease with the increase in x value. The sintering temperature of the Na-doped samples increased compared to the pure La 2/3(Mg 1/2W 1/2)O 3 (LMW) due to the estimated decrease in the concentration of A-site vacancies. The addition of Na + ion does not affect the dielectric permittivity greatly. The Q × f value decreases with the increase in x value, although the estimated concentration of A-site vacancies decreases with increasing x, which may be ascribed to the decrease of A/B-site ordering and domain size with the increase in x. The temperature coefficient of resonant frequency changed from negative values into positive values with the increase in x value.