Dielectric properties and charge compensation of Li and Co co-doped NiO (LCNO) ceramics prepared
by a simple sol–gel route have been investigated. The concentration of Co makes a great influence on
microstructure, dielectric properties and charge compensation mechanism of the LCNO ceramics. Grain
size of the ceramics increases from 5.6 m to 7.2 m with dependence on Co concentration. By using a
complex impedance analysis at different temperatures, the samples exhibit an electrically heterogeneous
structure, which is responsible for a giant dielectric permittivity. The relationship between the activation
energies of dielectric relaxation and conduction and charge compensation mechanism in this system
were discussed.