Permittivity and ac conductivity study of the layered perovskite [(CH3)(C6H5)3P]2MnCl4 showing evidence of phase transition

Mostafa, M. F.; Atallah, Ahmed

doi:10.1016/s0375-9601(99)00682-9

Cited by 36 publications

(10 citation statements)

References 17 publications

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“…The variation of both s and ln B with temperature is sensitive to the observed phase transformation, as reported earlier [26]. Anomalies in both s(T) and ln B(T) relations are observed at the transition temperature (T C ) from the magnetic region to the paramagnetic region.…”

Section: -Fesupporting

confidence: 73%

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Kaiser

Ata‐Allah

2005

Physica Status Solidi (b)

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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 -anioncation and cation -cation interactions present over the octahedral B-sites in the spinel structure.

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Section: -Fesupporting

confidence: 73%

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Kaiser

Ata‐Allah

2005

Physica Status Solidi (b)

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“…5. These changes in (s) and ln B(T) have been previously noted to occur at the transition temperature T c from the magnetic region to the paramagnetic region [17][18][19]. The values of T c determined from Fig.…”

Section: Resultssupporting

confidence: 52%

Conductivity and dielectric studies of copper–aluminate substituted spinel nickel ferrite

Ata‐Allah¹,

Kaiser²

2009

Journal of Alloys and Compounds

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“…7. These changes in (s) and lnB (T) have been previously noted to occur at the transition temperature [T C ] from the magnetic region to the paramagnetic region [44,45].…”

Section: Temperature and Frequency Dependence Of Conductivitymentioning

confidence: 77%

Cation distribution, hyperfine parameters and conduction mechanism in the ferrimagnetic system Cu_0.5Co_0.5Ga_xFe_2–_xO₄

Ata‐Allah

Kaiser

2005

Physica Status Solidi (b)

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Compositions having the chemical formula Cu 0.5 Co 0.5 Ga x Fe 2-x O 4 with (0.0 ≤ x ≤ 0.5) have been prepared by the usual ceramic processing from high-purity oxides. X-ray diffraction measurements are used for analyzing the composition, lattice parameter, density, porosity and grain size of these compounds. The area ratio of Fe 3+ at the tetrahedral A-and octahedral B-sites deduced from the spectral analysis of Möss-bauer measurements on the present spinel system gives evidence that Ga replaces Fe at A-site in the range 0.0 < x ≤ 0.3. As the Ga content increases (x > 0.3), it replaces Fe at B-site. This change in the site preference reflects an abrupt change in the hyperfine parameters with Ga content at x > 0.3. The electrical measurements as a function of temperature and frequency on these materials revealed semiconducting behavior. These results show a significant increase in the frequency dependence of conductivity as Ga content increases. Variation of the universal exponent s with temperature indicates the presence of smallpolaron (SP) hopping mechanism at low Ga content. As Ga substitution progressed, the overlap large polaron (OLP) becomes the predominant hopping mechanism in these compounds. The determined transition temperature T C of these samples is found to decrease linearly with increasing Ga content x. The results obtained in this study are interpreted in light of the cation-cation and cation-anion-cation interactions in the spinel structure.

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Permittivity and ac conductivity study of the layered perovskite [(CH3)(C6H5)3P]2MnCl4 showing evidence of phase transition

Cited by 36 publications

References 17 publications

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Conductivity and dielectric studies of copper–aluminate substituted spinel nickel ferrite

Cation distribution, hyperfine parameters and conduction mechanism in the ferrimagnetic system Cu_0.5Co_0.5Ga_xFe_2–_xO₄

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Permittivity and ac conductivity study of the layered perovskite [(CH3)(C6H5)3P]2MnCl4 showing evidence of phase transition

Cited by 36 publications

References 17 publications

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite

Conductivity and dielectric studies of copper–aluminate substituted spinel nickel ferrite

Cation distribution, hyperfine parameters and conduction mechanism in the ferrimagnetic system Cu0.5Co0.5GaxFe2–xO4

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Cation distribution, hyperfine parameters and conduction mechanism in the ferrimagnetic system Cu_0.5Co_0.5Ga_xFe_2–_xO₄