Very high temperature stability and excellent dielectric properties of a novel X9R-type Ca_(1-x)Sr_xCu_3Ti_4O_(12)/TiO_2 nanocomposite synthesized by a polymer pyrolysis technique

摘要

A polymer pyrolysis solution method was employed for the synthesis of Ca1-xSrxCu3Ti4O12/TiO2 ceramics. At 30 degrees C and 1 kHz, a high dielectric constant (epsilon') similar to 4193-10,110 and very low loss tangent (tan delta) similar to 0.009-0.039 were achieved. Interestingly, a Ca0.95Sr0.05Cu3Ti4O12/TiO2 ceramic sintered at 1060 degrees C for 5 h displayed a di-electric temperature coefficient (Delta epsilon') of less than +/- 15% over a temperature range -60-210 degrees C, which is wider than that ever reported. All ceramic samples displayed nonlinear J-E characteristics. Sr2+ doping significantly enhanced the breakdown field (E-b) and the nonlinear coefficient (alpha) with the highest E-b of similar to 20,548 V.cm(-1) and a value of similar to 52.06 in a Sr2+-doped ceramic where x=0.05. X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) were employed to study of the influence of Sr2+ doping on the microstructure and phase composition of the samples. The oxidation state of Cu ions in ceramic samples was investigated using X-Ray Absorption Near Edge Spectroscopy (XANES).