Microstructure and electrical properties of nano-scale SnO_2 hydrothermally coated CCTO-based composite ceramics

摘要

The hydrothermal method was successfully applied in this article to prepare nano-scale SnO_2 coated CCTO composite ceramics (CCTO/xSnO_2, X = 0, 0.1, 0.2, 0.3, 0.4). XRD, HRTEM, FESEM, EDS, XPS are systematically used to study the phase composition, surface structure, microstructure, composition distribution, and valence state of CCTO/SnO_2 composite ceramics. Sintered at a high temperature of 1040°C for 8 h, the prepared CCTO/ SnO_2 composite ceramic has obtained a dense microstructure and an exceptionally colossal dielectric constant(ε_r > 6.7x 10~5 at 25Hz, ε_r > 8.1x 10~4 at 1 kHz). The impedance spectroscopy and FESEM confrmed that the CCTO/ SnO_2 composite ceramics have the polarization behavior between grain boundaries on the micrometer scale and the polarization between nanocrystals on the nanometer scale. This nanoscale nanocrystalline barrier layers capacitor has become the primary source of the giant dielectric phenomenon of CCTO/SnO_2 composite ceramics.