Microwave dielectric properties of CaCu_(3)Ti_(4)O_(12) ceramics:A clue to its intrinsic dielectric response

CaCu_(3)Ti_(4)O_(12)(CCTO)is a potential dielectric material with giant permittivity,good stability over the wide temperature and frequency range.However,the dielectric responses of CCTO-based ceramics are mainly investigated in the frequency of 102-106 Hz,which is far low to clarify the intrinsic dielectric feature.So,microwave dielectric properties have been investigated for the CCTO porous ceramics sintered at low temperature(≤1000°C).Good microwave dielectric properties of permittivityε=62.7,quality factor Qf=3062 GHz and temperature coefficient of the resonant frequencyτf=179 ppm/°C are achieved for the CCTO ceramics sintered at 1000°C,the dielectric loss significantly decreases two orders to 0.002 compared to that of CCTO ceramics sintered at critical temperature of 1020°C confirmed by differential scanning calorimetry(DSC).This clue indicates that giant permittivity and high loss is not intrinsic for CCTO ceramics,but derives from composition segregation,liquid phase and defects associated with internal barrier layer capacitor(IBLC).It suggests that CCTO-based ceramics is a promising microwave dielectric materials with high permittivity.