Temperature treatment of nano-scaled barium titanate filler to improve the dielectric properties of high-k polymer based composites

A commercially available nano-scaled barium titanate powder was compounded with a polyester-styrene reactive resin to create a high-k polymer-composite material. The influence of a temperature treatment on the filler was examined for treatment temperatures between 500 and 1200 °C. As a result grain and particle growth as well as lattice relaxation was induced into the powder particles. The resulting composite permittivity rises from 9.2 to 25.0 (at room temperature, 1 kHz, filler load 60 wt%/∼22 vol%) and the dielectric loss factor drops to values below 0.005 as a result of this treatment. The changes in lattice structure, powder morphology and composite viscosity were determined by XRD, SEM, BET, He-pycnometry and rheology measurements. The temperature dependency of the dielectric properties of the pure polymer and the composite were measured between −60 and 70 °C. The temperature dependency of the polymer matrix is superimposed with the temperature characteristic of the BaTiO₃.