The real part of dielectric constant (ε΄) and dielectric loss tangent
(tanδ) were studied for Al.- substituted Ni – Cd spinel ferrites having the
chemical formula Ni0.7 Cd0.3 Fe2-x Alx O4 where [x= 0.4, 0.6, 0.8,and 1] This is
carried our in the range of temperature from room temperature up to 650 K
and applying frequencies from 102 to 105 Hz. The distribution of Al ions in the
B and A sites has changed with changing x and was found to affect the
dielectric constant ε ΄ of the samples which have relatively high values. The
frequency dependence of the dielectric constant was found to exhibit two
different behaviors related to temperature values and indicating the presence
of two types of charge carriers at high temperatures. The frequency
dependence of tanδ shows the existence of broad peaks at low temperature
range, which indicates that there is a distribution of relaxation times rather
than a single relaxation time.