Spectral studies of nano Ni ferrite doped with Cr ions O. M. Hemeda, M. I. Abdel-Ati, B. I. Salem, A. M. A. Henaish and F. S. El-Sbakhy Eur. Phys. J. Plus, 133 12 (2018) 531 Published online: 20 December 2018 DOI: 10.1140/epjp/i2018-12346-9