Li₂WO₄ Composite Ba₃Ti₄Nb₄O₂₁ Microwave Dielectric Ceramics with Near-Zero Temperature Coefficient and Low-Temperature Sintering for 5G Communication Devices

Abstract In order to solve the problem of device miniaturization, it is urgent to develop high performance medium K materials. A series of (1-x) Ba 3 Ti 4 Nb 4 O 21 -x Li 2 WO 4 ceramics (1-xBTN-xLW, x=12, 15, 17 and 20 mol%) were fabricated by soild-state reaction method. Li 2 WO 4 as the effective sintering aids (~640°C) not only promoted ceramic densification and also decreased the temperature to 925°C. Among them, the 0.83BTN-0.17LW ceramic achieved best microwave performance with ε r ~21.85, Q× f ~10534 GHz, τ f ∼-7.78 ppm/°C. Especially, the second phase BaWO 4 played major factor on microwave performance, making high K materials transfer into medium K materials and decrease the loss. More encouragingly, the temperature coefficient τ f was near zero. The above outstanding results signified that the 0.83BTN-0.17LW ceramic was expected to be a candidate material for LTCC miniaturized devices.