The Li₂O-Nb₂O₅-TiO₂ composite microwave dielectric ceramics with adjustable permittivities

A group of new y M-phase/(1-y) Li_2+xTi_1-4xNb _3xO₃ composite ceramics with adjustable permittivities for low-temperature co-fired ceramic applications was initially investigated in the study. The 0.5 M-phase/0.5 Li_2+xTi_1-4xNb _3xO₃ (x=0.01, 0.02, 0.04, 0.06, 0.081) composite ceramics were first investigated to find the appropriate "Li₂TiO ₃ss" composition (x value). The best dielectric properties of ε_r=40.1, Q × f values up to 9318 GHz, τ_f=25 ppm/°C, were obtained for the ceramics composites at x=0.02. Based on the good dielectric properties, the suitable "Li₂TiO ₃ss" composition with x=0.02 was mixed with the Li _1.0Nb_0.6Ti_0.5O₃ powder as the ratio of y "M-phase"/(1-y) "Li₂TiO₃ss" (y=0.2, 0.4, 0.5, 0.6, 0.8). By adjusting the y values, the group of composite ceramics could exhibit largely are adjustable permittivities varying from ∼20 to ∼60, while Q × f and τ_f values relatively good. Nevertheless, in this study, because there are interactions between the M-phase and Li₂TiO₃ss during sintering process, their microwave dielectric properties could not be predicted precisely by the empirical model.