Low frequency conductivity study of gallium-substituted magnesium-copper spinel ferrite
| Autor: | S. S. Ata‐Allah, M. Kaiser |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Chemistry
Transition temperature Spinel Analytical chemistry chemistry.chemical_element Activation energy engineering.material Condensed Matter Physics Polaron Electronic Optical and Magnetic Materials Paramagnetism Nuclear magnetic resonance Ferrimagnetism Electrical resistivity and conductivity engineering Gallium |
| Zdroj: | physica status solidi (b). 242:3138-3148 |
| ISSN: | 1521-3951 0370-1972 |
| Popis: | Mixed ferrites with the chemical formula Mg 0.5 Cu 0.5 Ga x Fe 2-x O 4 (0.0 ≤ x ≤ 0.5) were prepared by a ceramic route. X-ray diffraction results confirmed the presence of single-phase spinel structure for these samples. Electrical properties of these ferrites at various compositions were investigated from room temperature up to 550 K in the frequency range 10 2 -10 5 Hz. The obtained results revealed semiconductor behavior at high frequency and metallic behavior at low frequency in these materials. All studied compositions exhibit a transition with a change in the slope of the conductivity versus temperature curve. The obtained transition temperature T C is found to decrease linearly with increasing Ga concentration. As Ga substitutes Fe in these compounds the activation energy for electrical conduction in the ferrimagnetic region (E f ) has a small variation with frequency. In contrast, the activation energy in the paramagnetic region (E p ) shows undefined behavior reflecting the nature of this disordered state. The relation of the universal exponent s with temperature gives evidence for the presence of the large overlap polaron (LOP) hopping conduction mechanism in these compounds. The obtained results are explained in the light of the cation-anion-cation and cation-cation interactions present over the octahedral B-sites in the spinel structure. |
| Databáze: | OpenAIRE |
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