Anisotropic dielectric properties of LiNb0.6Ti0.5O3 microwave ceramics by screen-printing templated grain growth

In this work, anisotropic LiNb0.6Ti0.5O3 (LNT) template particles are prepared by molten salt synthesis in LiCl flux. Plate-like particles with diameters of 5-20 μm and thicknesses of 0.5-2.0 μm synthesized at 1000°C are chosen as templates. Highly textured microwave ceramics of M-phase LNT with tunable dielectric properties are fabricated by a novel screen-printing templated grain growth technique (sp-TGG), and their characteristics and dielectric properties are studied systematically. Dielectric anisotropy is observed in dielectric constant (εr) and the temperature coefficient of dielectric constant (τε) at 1 MHz. LNT(//) samples exhibit lower εr (=55.3) than randomly oriented ceramics and a positive temperature coefficient τε (75 ppm/°C), whereas, LNT(⊥) samples exhibit higher εr (=83.6) and a negative temperature coefficient τε (= -120 ppm/°C). The textured ceramics also exhibit anisotropic and excellent properties at microwave frequency, with LNT-M(//) showing εr = 57.9, Q × f = 6325 GHz, τf = -14 ppm/°C and LNT-M(⊥) showing εr = 81.8, Q × f = 5751 GHz, τf = 43 ppm/°C. By tailoring along different directions, continuously tunable dielectric constant ranging from 55 to 83 could be obtained, and τf could be changed from -14 to 43 ppm/°C. These findings can be technologically beneficial for wireless communication devices.