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Low frequency conductivity study of gallium‐substituted magnesium–copper spinel ferrite
Author(s) -
Kaiser M.,
AtaAllah S. S.
Publication year - 2005
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200541116
Subject(s) - ferrimagnetism , spinel , polaron , gallium , activation energy , electrical resistivity and conductivity , ferrite (magnet) , paramagnetism , conductivity , materials science , analytical chemistry (journal) , thermal conduction , copper , condensed matter physics , chemistry , magnetization , metallurgy , magnetic field , physics , quantum mechanics , chromatography , electrical engineering , composite material , engineering , electron
Abstract 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. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)