Very high performance dielectric and non-Ohmics properties of CaCu3Ti4.2O12 ceramics for X8R capacitors

摘要

CaCu3Ti4O12 (CCTO) and CaCu3Ti4.2O12 (TiO2) precursor powders were prepared by the polymer pyrolysis solution method. Effect of sintering time/temperature on microstructural, dielectric and non-linear properties of CCTO and TiO2 ceramic samples obtained by sintering all precursor powders at various sintering conditions were investigated. Interestingly, very low tan delta similar to 0.008 and high epsilon' similar to 7221 with temperature coefficients Delta epsilon' +/- 15% in a wide temperature range of - 60 to 180 'C were achieved in the TiO2 ceramic sample sintered at 1025 degrees C for 12 h (TiO2-2 sample). This suggested the potential use of TiO2-2 sample for EIA X5R, X7R and X8R capacitors. Moreover, sintering could enhance the non-linear characteristics of all ceramic samples with a non-linear coefficient (alpha) of similar to 29.04 and the maximum breakdown field (E-b) of similar to 12,221 V/cm(-1) in TiO2-2 sample. Enhancement of epsilon' due to the sintering was suggested to originate from the promotion of oxygen vacancies and the increase of grain size.