Sintering Behavior, Microstructure, and Microwave Dielectric Properties of Li4(1+x)WO5 (0 ≤ x ≤ 0.08)

A series of low-firing Li 4(1+ x ) WO 5 ( x  = 0.02, 0.04, 0.06, 0.08) ceramics were prepared using the solid-state reaction method. Effects of excess lithium on the crystal structure, sintering behavior, and microwave dielectric properties were studied. For x  < 0.06 samples, only a single Li 4 WO 5 phase was formed, while a secondary phase detected as Li 6 WO 6 appeared in the x  = 0.08 sample. The relative density increased obviously with increasing amount of excess lithium, resulting in the remarkable increase in quality factor. The sample with x  = 0.04 sintered at 950°C obtained a high relative density of ∼95.1% and good microwave dielectric properties with ε r  ∼ 9.5, Q  ×  f  ∼ 50200 GHz (at 12.2 GHz), τ f  ∼ −3.2 ppm/°C.