High-frequency dielectric behaviour of polycrystalline zinc substituted cobalt ferrites

• Published in: Journal of materials science Vol. 34; no. 13; pp. 3169 - 3176
• Main Authors: RAMANA REDDY, A. V, RANGA MOHAN, G, RAVINDER, D, BOYANOV, B. S
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-07-1999; Springer Nature B.V
• Subjects: Cobalt ferrites; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Curie temperature; Dependence; Dielectric loss; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Frequency ranges; Materials science; Permittivity; Permittivity (dielectric function); Physics; Substitutes; Zinc; Inorganic compounds; Phase transformations; Transition element compounds; Polycrystals; Cobalt oxides; Experimental study; Zinc oxides; Ferrites spinels; Solid solutions; Dielectric losses; Chemical composition; Iron oxides; Quaternary compounds; Permittivity
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004625721864

The dielectric constant (ɛ′) and complex dielectric constant (ɛ′′) of zinc substituted cobalt ferrites have been measured at room temperature in the high frequency range 100 kHz to 1 MHz. The values of dielectric loss tangent (tan δ) have been computed from ɛ′ and ɛ′′. Plots of dielectric constant (ɛ′) versus frequency show a normal dielectric behaviour of the spinel ferrites. The frequency dependence of dielectric loss tangent (tan δ) is found to be abnormal, giving a peak at certain frequency for all the ferrites under investigation. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. The dielectric constant for these mixed ferrites is approximately inversely proportional to the square root of the resistivity. A plot of dielectric constant versus temperature shows a transition near the Curie temperature. An attempt is made to explain the possible mechanism for this observation.