Abstract
B doped CaCu3Ti4O12 (CCTO), Sr doped CCTO and (B + Sr) co-doped CCTO ceramics were synthesized using the citrate precursor process and were sintered at 1080°C for 3 h. The effects of B and/or Sr doping on dielectric properties, Raman spectra and resistance were studied. Raman results corroborate with the results of x-ray diffraction, and Raman spectra show a multiphonon phenomenon. The pure CCTO phase can be obtained by citrate precursor processing and a short sintering time. The micrographs reveal that B and Sr additions can speed the grain growth, and a dense and homogenous microstructure was obtained for B and Sr co-doped ceramic. The addition of B and Sr can increase the grain boundary resistance and enhance dielectric properties with dielectric constant of 12108 and dielectric loss of 0.044 at 10 kHz. Moreover, B and Sr additions can enhance the frequency stability (between 100 Hz and 50 kHz) and temperature stability (between 20°C and 100°C) of dielectric loss. The present results show that the microstructure characteristics and grain boundary response are the primary factors in improving the dielectric properties of CCTO ceramics.
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