Liquid phase deposition process to deposit TiO2 in the porous Mg2SiO4 ceramics

Abstract

We propose use of a liquid phase deposition method (LPD) to prepare the composite ceramics with no chemical reaction between the two phases. Mg2SiO4–TiO2 composite ceramics is desirable for microwave/millimeter-wave dielectric devices, because the appending TiO2 into Mg2SiO4 improves the temperature coefficient of resonant frequency (τf) to 0 ppm/°C. However, there is a problem that the secondary phases: MgSiO3 and MgTi2O5 are created during sintering at elevated temperatures. The presence of the secondary phase results in decrease of the quality factor (Q·f). To prevent the production of the secondary phase, we try to investigate another route to prepare the Mg2SiO4–TiO2 composite ceramics using a liquid phase deposition (LPD) process as follows: Porous Mg2SiO4 ceramics were prepared by sintering Mg2SiO4 with pore-forming agents. Then, TiO2 was deposited into the pores using LPD. In particular, this study focused on two conditions to deposit TiO2 in porous Mg2SiO4: (1) the firing temperature after depositing TiO2 in the porous Mg2SiO4 and (2) the concentration of the precursor solution for the LPD.