Abstract—A series of copper substituted nickel nano ferrites with the compositional formula Ni  _1-X  Cu_XFe ₂ O₄ (X=0,  0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) were prepared by the Citrate gel auto combustio n technique and sintered at 700^oC for 5 hr. The X-ray difractrograms (XRD) clearly exhibited the existence of single phase cubic spinel structure. The crystallite size was found in the range of 36-58nm. With the increment of Cu content the X-ray density and porosity were found to increase where as the bulk density was found to decrease. The DC electrical properties were carried out by two-probe method from room temperature to well beyond the Curie temperature. DC electrical resistivity decreases with increase of temperature ensuring the semiconducting nature of the ferrites. The DC electrical conductivity found to increase with increase of Cu content and reaches maximum at X=1.0 at which the activation energy for conduction becomes minimum. The activation energy in the ferrimagnetic region is in general lesser than that in the paramagnetic region. The activation energy was found to decrease with the increase of Cu content. The Curie temperature determined from DC electrical properties was found in satisfactory agreement with that determined from Loria technique. The DC electrical resistivity results are discussed in terms of hopping model.

Index Terms—Ni–Cu nano ferrite, x-ray density, bulk density, porosity, DC electrical properties.

K. Vijaya Kumar is with Department of Physics, JNTU Hyderabad College of Engineering, Nachupally (Kondagattu), Karimnagar-505501, Andhra Pradesh, India (e-mail: kvkphd@gmail.com).
Rapolu Sridhar is with Vignan’s Institute of Technology & Aeronautical Engineering College, Deshmukhi, Nalgonda-508284, Andhra Pradesh, India (e-mail: rapolu31@gmail.com).
D. Ravinder is with Department of Physics, Nizam College, Bashbeerbagh, Osmania University, Hyderabad- 500001, Andhra Pradesh, India(e-mail: ravindergupta28@rediffmail.com).
K. Rama Krishna is with Department of Physics, Malla Reddy College of Engineering & Technology, Secunderabad, India (e-mail: ramu521@yahoo.com).

Cite: K. Vijaya Kumar, Rapolu Sridhar, D. Ravinder, and K. Rama Krishna, "Structural Properties and Electrical Conductivity of Copper Substituted Nickel Nano Ferrites," International Journal of Applied Physics and Mathematics vol. 4, no. 2, pp. 113-117, 2014.