Simple synthesis, structural and optical properties of cobalt ferrite nanoparticles A. V. Ravindra, M. Chandrika, Ch. Rajesh, Pratap Kollu, Shaohua Ju and S. D. Ramarao Eur. Phys. J. Plus, 134 6 (2019) 296 Published online: 26 June 2019 DOI: 10.1140/epjp/i2019-12690-2