Microwave dielectric properties of Li(Mg_(1-x)Ni_x)PO_4 ceramics for LTCC applications

摘要

Li(Mg_(1-x)Ni_x)PO_4 (x=0-0.1) ceramics were prepared by the conventional solid-state ceramic method. The formation of single-phase Li (Mg_(1-x)Ni_x)PO_4 (x=0-0.1) solid solutions is confirmed by the X-ray diffraction (XRD) patterns. Ni~(2+) substitution for Mg~(2+) can lower the sintering temperature and improve the microwave dielectric properties of LiMgPO_4 ceramics. The LiMg_(0.95)Ni_(0.05)PO_4 ceramic sintered at 875 °C for 2 h can reach a maximum relative density of 97.1% and shows the microwave dielectric properties of ε_r=6.91, Q × f =98,600 GHz, and Ti= -55.3 ppm/°C. The large negative τ_f - value is adjusted to nearly zero with the addition of TiO_2. The LiMg_(0.95)Ni_(0.05)PO_4-TiO_2 composite ceramic with 11 vol% TiO_2 sintered at 875 °C for 2h exhibits good microwave dielectric properties of ε_r=9.88, Q × f = 50,800 GHz, and τ_f=-1.4ppm/°C. The composite ceramic is chemically compatible with silver and promising for low-temperature cofired ceramic applications.