Effect of ZnO on the microstructure and dielectric properties of BaTiO3 ceramic coatings prepared by plasma spraying

Three contents of zinc oxide (2 wt %, 4 wt % and 6 wt %) were added into raw BaTiO3 powders. The maximum relative permittivity value (εr) is in the range 230-406 and the dielectric loss (tanδ) varies between 0.18 and 0.09 for all ZnO modified BaTiO3 coatings for frequency1 kHz at ambient temperature. The reasons for enhancing the relative permittivity are attributed to the elimination of micro-cracks and pores. The detail discussion was conducted on the characteristics morphologies (cross section, fracture surface and spreading behavior of BaTiO3+xwt. % ZnO composite powders) and phase. With the analysis, the addition of ZnO leads to the improvement in the melting state and increment in amorphous phase. Zn existed in the form of secondary phase (ZnO) and substitution in the BaTiO3 lattice. The enhancement in structure and dielectric performance is highly discussed based on the phase equilibria and chemical defect.