PREPARATION OF LOW-LOSS TITANIUM DIOXIDE FOR MICROWAVE FREQUENCY APPLICATIONS

摘要

Dense titanium dioxide (TiO_2) was prepared from commercially available high-purity powders. The powders were first deagglomerated and colloidally stabilized in aqueous NH_3 to form a stable suspension. The suspension was screened, followed by colloidal-filtration, drying and sintering. Sintering at 1000℃ for 10 hours resulted in > 99.5% density and 2.2 μm grains. The dielectric loss of the dense-sintered TiO_2 was 1.4×10~(-4) at 6.4 GHz at room temperature. This low dielectric loss is attributed to a low sintering temperature and homogeneous microstructure. Dense, low-loss TiO_2 is particularly interesting for microwave applications because of its very high dielectric constant at GHz frequencies. The process presented here will be used to make dense TiO_2 parts with complex shape in new microwave antenna concepts, for its high dielectric constant and low dielectric loss at microwave frequencies.