Tuning of structural, electrical and transport behaviour of cobalt nanoferrite by dysprosium ions substitution

Present study explores the structural, electrical and transport properties of dysprosium cation (Dy3+) substitution on (Fe+3) site in cobalt nonoferrites [CoFe2-xDyxO4 (Dy(x) = 0.00, 0.05, 0.10 & 0.15)] prepared by sol-gel chemical route. X-ray diffraction pattern confirms the pure cubic spinel structure for all samples. The average crystallite size was found in the range of 49 to 72 nm with no linear variation with incresing doping concentration of (Dy3+) ions. The values of lattice parametres is found to be changed from 8.34 to 8.39 & ANGS; for pristine cobalt nanoferrite (CoFe2O4) and sample having highest doping concentration i.e. Dy(x) = 0.15 respectively. The porosity observed to be decrease linearly with increasing (Dy3+) ion concentration. The electrical properties have been investigated by analyzing dielectric behaviour in the frequency range of 75 kHz- 5 MHz and temperature range of 100K- 400K. The frequency dependent dielectric behaviour at different temperatures is explained in terms of Maxwell-Wagner and Koop's phenomenological models. Ferrite with Dy(x) = 0.15 have achieved highest dielectric constant in the range of 441 to 5234 which was measured at 100K (5 MHz) and 400K (75 kHz) respectively. The electrical resistivity of each of the ferrite sample reduces with rising temperature representing the semiconductor behaviour of all ferrites which is due to the thermally triggered charge carriers hopping between (Fe2+) and (Fe3+) ions and associated with higher drift mobility. The increase in drift mobility at room temperature with increasing (Dy3+) ion concentration is considered to be a sign of improved transport behaviour. The high value of dielectric constant and low dielectric loss of all these ferrites make them suitable for the memory storage devices.

Automated summary

This study investigates the structural, electrical and transport properties of cobalt nanoferrites (CoFe2O4) doped with dysprosium cation (Dy3+) on the iron (Fe3+) site. The results confirm that the samples maintain a pure cubic spinel structure. The average crystallite size ranges from 49 to 72 nm and is not affected by the concentration of Dy3+ ions. The lattice parameters vary from 8.34 Å for pristine CoFe2O4 to 8.39 Å for the sample with the highest doping concentration (Dy(x) = 0.15). The porosity decreases with increasing Dy3+ ion concentration. The electrical properties are analyzed through dielectric behavior at different frequencies and temperatures. The ferrite with Dy(x) = 0.15 exhibits the highest dielectric constant in the range of 441 to 5234, indicating its suitability for memory storage devices.