Effect of Cu substitution on conductivity of Ni-Al ferrite

Electrical properties of Cu substituted Ni-Al ferrite Ni1-xCuxAl3Fe2-yO4, with (0.0 < x < 1.0 and y = 1.0) are investigated by a.c, conductivity measurements in the frequency range (10(2)-10(5) Hz) and over the temperature range (300-600 K). The obtained results of these materials reveal a semiconducting behavior at low concentration of Cu. A semiconducting-to-metallic transition has been observed with increasing Cu content in these compounds. All studied compositions exhibit a transition with change in the slope of conductivity versus temperature curve. This transition temperature is found to decrease linearly with increasing Cu concentration x. The results of conductivity measurements an explained in the light of the cation-anion-cation and cation-cation interactions at the octahedral B-sites. (C) 2000 Elsevier Science Ltd. All rights reserved.