Structural and magnetic properties of nanograined Ni0.7−yZn0.3CayFe2O4 spinels Mahmoud Hosseny Makled, Nabil M. Shash and Hesham K. Abdelsalam Eur. Phys. J. Appl. Phys., 66 3 (2014) 30402 Published online: 10 June 2014 DOI: 10.1051/epjap/2014130573