| Abstract |
A novel concept to simultaneously modify the electric responses of the grain and grain boundaries of
CaCu3Ti4O12 ceramics was proposed, involving doping with F anions to improve the giant dielectric
properties. The grain growth rate of CaCu3Ti4O12 ceramics was enhanced by doping with F anions,
which were found to be homogeneously dispersed in the microstructure. Substitution of F anions can
cause an increase in the resistance of the insulating grain boundary and a decrease in the grain
resistance. The former originated from the ability of the F dopant to enhance the Schottky barrier
height at the grain boundaries, leading to a great decrease in the dielectric loss tangent by a factor of 5
(tan d < 0.1). The latter was primarily attributed to the increase in Ti3+ and Cu+ concentrations due to
charge compensation, resulting in a significantly enhanced intensity of space charge polarization at the
grain boundaries. This is the primary cause of the increase in dielectric permittivity from z104 to z105.
The giant dielectric and electrical properties were well described by the Maxwell–Wagner polarization
relaxation based on the internal barrier layer capacitor model of Schottky barriers at the grain boundaries |
Publication
Journal Publication
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