Deficient or excessive CuO‐TiO 2 phase influence on dielectric properties of CaCu 3 Ti 4 O 12 ceramics

Abstract The influence of the CuO–TiO 2 phase ( CT ) on dielectric properties of the CCTO ceramic was investigated. CaCu X T i Y O 12 ( CC X T Y O ) powders were prepared based on the coprecipitated method, where 2.70 ≤ x ≤ 3.30 and 3.25 ≤ y ≤ 4.75. XRD patterns confirmed the presence of CCTO and also the secondary phases as CuO, TiO 2 , and CaTiO 3 for each sample and aided in its quantification. Scanning Electron Microscopy ( SEM ) shows secondary phases evolution in the grain boundaries, and its influence on size and morphology of the grains. Impedance spectroscopy measurements showed that the ceramics with lower amount of CuO and TiO 2 phases ( CT /deficient ceramics) exhibited the highest ε′ values (2.1 × 10 4 at 1 kHz for CC 2.9 T 3.75 O ceramic). Also, CT /deficient ceramics showed lower tanδ values (0.090 at 1 kHz for CC 2.9 T 3.75 O ceramic) than ceramics prepared with excessive CuO–TiO 2 phase (0.241 at 1 kHz for CC 3.1 T 4.25 O ceramics). The deficiency of CuO and TiO 2 phases associated with high percentage of CCTO and CaTiO 3 phases resulted in ceramics with the higher ε′ values.