Relaxation characteristics of NiGaxFe2−xO4

Dynamic dielectric measurements are carried out for NiGaxFe2−xO4 ferrites with 0.0≤x≤2.0 over the frequency range 102 to 105 Hz at temperature between 300 and 900 K. The variation of dielectric permittivity ε′ with frequency at different temperatures shows a normal behavior for the studied compounds, while the variation of dielectric loss tangent with frequency at different temperatures shows abnormal behavior with more than one relaxation peak. This behavior is attributed to a collective contribution of two types of carrier (p and n) to the polarization. Observed relaxations are found to fit the Cole–Cole arc with a distribution of relaxation times.