High-performance 0.9Al2O3-0.1TiO2 microwave dielectric ceramics prepared by digital light processing

In this work, the 0.9Al2O3-0.1TiO2 ceramic sample with good microwave dielectric properties and complex structures can be well fabricated by digital light processing (DLP). A relationship between dispersant content and rheological behavior of 0.9Al2O3-0.1TiO2 slurry was explored. When dispersant content was 3.0 wt%, 0.9Al2O3-0.1TiO2 slurry with high solid loading (50 vol%) and low viscosity (2.9 Pa s) could be obtained. 0.9Al2O3-0.1TiO2 ceramic parts with high accuracy were fabricated successfully by adding 3.0 wt% photoinitiator under 600 mJ/cm2 exposure energy. With the increase of sintering temperature from 1400 °C to 1600 °C, relative density, dielectric constant (εr), and quality factor (Q × f) of 0.9Al2O3-0.1TiO2 ceramic sample increased first and then decreased, and all reached the maximum value at 1550 °C due to the uniformity and densification of microstructures. The temperature coefficient of resonant frequency (τf) value showed an almost monotonous increase, changing from negative to positive, and near-zero τf value at 1550 °C. In addition, 0.9Al2O3-0.1TiO2 ceramic samples sintered at 1550 °C fabricated by DLP method presented much better microwave dielectric properties: εr = 11.30 ± 0.02, Q × f = 35,345 ± 143 GHz (@∼12 GHz), τf = 2.16 ± 0.21 ppm/°C than that of by dry pressing method: εr = 11.16 ± 0.11, Q × f = 30,195 ± 257 GHz (@∼12 GHz), τf = 4.45 ± 0.13 ppm/°C, especially the Q × f value achieved a 17% increase. Accordingly, DLP technique, which has advantages of producing relatively high properties and complex geometry of microwave dielectric ceramics as well as without extra high-cost mold, greatly satisfies application requirements.