ORIGINAL PAPER Optimised polyaniline–cadmium ferrite nanocomposite: synthesis, characterisation and alternating current response S. Kotresh 1 • Y. T. Ravikiran 1 • S. C. Vijaya Kumari 2 • CH. V. V. Ramana 3,4 • A. S. Anu 5 • K. M. Batoo 6 Received: 22 May 2017 / Revised: 18 August 2017 / Accepted: 22 August 2017 Ó Springer-Verlag GmbH Germany 2017 Abstract In the present work, optimised polyaniline–cadmium ferrite (PANI– CdFe 2 O 4 ) composite was prepared by chemical polymerization method. Compar- ative structural and morphological studies of PANI, CdFe 2 O 4 and the composite were carried out by Fourier transform infrared spectroscopy, X-ray diffraction study and scanning electron microscopy. Highly crystalline nature of the composite composed of nanosized particles was confirmed by transmission electron micro- scopy studies. The dielectric loss tangent at room temperature for PANI, CdFe 2 O 4 and the composite were investigated in the frequency range 50 Hz–5 MHz. The Maxwell–Wagner type polarisation in PANI and CdFe 2 O 4 was confirmed by the decrease in their dielectric loss tangents with increasing frequency. But for the composite, a loss tangent peak due to relaxation losses implying resonance between hopping frequency of charge carriers and applied alternating current electric field was obtained. Debye type single relaxation in PANI and the distribution of relax- ation in the composite were confirmed by their respective complex plane impedance & Y. T. Ravikiran ytrcta@gmail.com 1 Department of PG Studies and Research in Physics, Government Science College, Chitradurga, Karnataka 577501, India 2 Department of Physics, SJM College of Arts, Science and Commerce, Chitradurga, Karnataka 577501, India 3 Department of ECE, Chirala Engineering College, Ramapuram Beach Road, Chirala, Andhra Pradesh 523157, India 4 Department of Electrical and Electronics Engineering Science, University of Johannesburg, PO Box 524, Auckland Park Campus, Johannesburg 2006, South Africa 5 International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686560, India 6 King Abdullah Institute for Nanotechnology, King Saudi University, P.O. Box 2455, Riyadh 1145, Saudi Arabia 123 Polym. Bull. DOI 10.1007/s00289-017-2169-x