Mg2SiO4-TiO2 composite ceramics prepared using a liquid phase deposition process

Forsterite (Mg2SiO4) indicates a high quality factor (Q center dot f) of 270,000 GHz and a low dielectric constant E > (r) of 6.8, which are applicable for microwave and millimeter-wave dielectric devices. However, a large negative temperature coefficient of resonant frequency (tau (f)) of -73 ppm/A degrees C hinders stability. Actually, Mg2SiO4-TiO2 composite ceramics prepared by ordinary solid state reaction showed improved tau (f) to 0 ppm/A degrees C. However, Q center dot f of the composite ceramics decreased because other phases such as MgTi2O5, MgTiO3 and MgSiO3 were created in the reaction between TiO2 and Mg2SiO4 during sintering. This study uses a different process to prepare the Mg2SiO4-TiO2 composite ceramics to prevent the production of the secondary phase. Porous Mg2SiO4 ceramics were prepared by sintering Mg2SiO4 with pore-forming agents. Then, TiO2 was inserted into the pores using liquid phase deposition (LPD). Deposited TiO2 in the pores was anatase form. The increase of the inserted anatase TiO2 amount contributed to improvement of tau (f).