A Viable Route for Dense TiO_2 with a Low Microwave Dielectric Loss

摘要

Dense, high-purity TiO_2 was prepared from commercially available powders. These powders were deagglomerated, colloidally stabilized in aqueous NH_3, followed by screening to remove residual agglomerates. Homogeneous compacts were formed using colloidal-filtration followed by sintering. TiO_2 with > 99.5% density and 400 Mpa flexural strength was obtained at a sintering temperature as low as 1000℃. The dielectric loss of this TiO_2 was 1.4 × 10~4 at 6.4 GHz at room temperature. This implied that the product of the quah'ty factor and frequency, (Q × f) = f/tan δ, was 46000 GHz, ～7.6 times higher than 6000 GHz (Q < 2000 at 3 GHz) reported previously. This high-quality factor is attributed to the low sintering temperature as well as a homogeneous dense microstructure with 2.2 urn grain size. The process described can be apph'ed to reah'ze complex TiO_2 structures in new microwave antenna concepts, that require components with a high dielectric constant and low dielectric loss.