X-ray diffraction and Mossbauer studies on superparamagnetic nickel ferrite ('NI''FE' IND. 2''O' IND. 4') obtained by the proteic sol–gel method - Nogueira, N. A. S.; Vasconcelos, I. F.; Utuni, V. H. S.; Silva, Y. C.; Miranda, M. A. R.; Sasaki, J. M.; Kiyohara, Pedro Kunihiko (MATERIALS CHEMISTRY AND PHYSICS, 2015)