Microstructure and dielectric properties of ST ceramics prepared by the sol–gel combustion technique with chitosan addition

The effect of chitosan content and sintering temperature on phase formation, microstructure, physical properties and dielectric properties were studied. Strontium titanate (ST) ceramic powders were synthesized by the sol–gel combustion method with various chitosan contents (1, 3, 5, 7 and 10 mol%) addition. The synthesized samples were characterized by XRD, FT-IR, SEM and TEM. The results showed that the obtained ST powders were uniform in size with a cubic perovskite structure. The highest percentage of the perovskite phase and well crystallinity were exhibited at 3 mol% chitosan addition, while the perovskite phase decreased with increasing chitosan content. It was demonstrated that the chitosan adding process is beneficial to the homogenously distributed in the ST preparation. The highest density of the sintered ST ceramic was 4.3 g/cm3 (84% of theoretic value) when sintered in the range of 1200–1300 °C for 4 h and had an average grain size of approximately 437±61.4 nm. The high dielectric constant of ST ceramics sintered at 1200 °C for 4 h was 504 (at 1 kHz).