Ti deficiency effect on the dielectric response of CaCu_3Ti_4O_(12) ceramics

摘要

Single phase ceramics CaCu_3Ti__(4.0)O_(12) and CaCu_3Ti_(3.9)O_(12) have been prepared using the traditional solid-state reaction method. Compared with the stoichiometric ceramics CaCu_3Ti_(4.0)O_(12), Ti-deficient ceramics CaCu_3Ti_(3.9)O_(12) have the larger lattice parameter, the higher force constant, and smaller dielectric constant and the lower dissipation factor, although their fundamental characters of dielectric response are similar. Their characteristic relaxation frequencies are not well fitted with the Arrhenius Law but a tentatively supposed relation. With the Cole-Cole Law, the fitted broadened factors of dissipation peaks are 0.5433 and 0.8651 for CaCu_3Ti_(3.9)O_(12) and CaCu_3Ti_(4.0)O_(12), respectively. All facts mentioned above imply that mutually correlated motion of Ti ions or defects may be expected to be responsible for the giant dielectric constant and high dissipation factor of CaCu_3Ti_(4.0)O_(12).