This paper reports the dielectric properties of fly ash. The dielectric measurements were performed as a function of frequency and temperature. The sample of fly ash shows almost similar behaviour in the frequency and temperature range studied. The large value of dielectric constant in the typical frequency range is because of orientation polarization and tight binding force between the ions or atoms in the fly ash. The sample of fly ash is of great scientific and technological interest because of its high value of dielectric constant (10⁴).

Ceramics of BaTiO₃ co-doped with Gd and Cr at Ba-site was synthesized via solid-state reaction route. Surface morphology shows the increase in grain size with the increase of Cr-content below 3 mol%. The high value of 𝜀 in the synthesized samples is associated with space charge polarization and inhomogeneous dielectric structure. Gd is diffused well into the most of Ba sites and vacancies leaving very few defects or voids for the generation of absorption current which results in dielectric loss. Below 3 mol% of Cr-concentration, dissipation factor was improved. Increase in a.c. conductivity with rise of temperature is due to increase in thermally activated electron drift mobility of charges according to the hopping conduction mechanism. Moreover, samples show the positive temperature coefficient of conductivity, which is most desirable for developing highly sensitive thermal detectors and sensors. Also, higher frequency indicates motion of charges in the ceramic samples.