Nanostructured Al3+ doped Ni0.75Zn0.25Fe2-xAlO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ferrites were synthesized via the wet chemical method. X-ray diffraction, transmission electron microscopy, and magnetization measurements have been used to investigate the structural and magnetic properties of spinel ferrites calcined at 950 degrees C. With the doping of Al3+, the particle size of Ni0.75Zn0.25Fe2-xAlO4 first increased to 47 nm at x = 0.4 and then decreased down to 37 nm at x = 1. The main two absorption bands in IR spectra were observed around 600 cm(-1) and 400 cm(-1) corresponding to stretching vibration of tetrahedral and octahedral group Fe3+-O2-. Saturation magnetization and hyperfine field values decreased linearly with Al3+ due to magnetic dilution and the relative strengths of Fe-O-Me (Me = Fe, Ni, Zn, and Al) superexchanges. The coercive field showed an inverse dependence on ferrite particle size with minimum value of 82 Oe for x = 0.4. A continuous drop in Curie temperature was observed with the Al3+ substitution. From the Mossbauer spectral analysis and X-ray diffraction analysis, it is deduced that Al3+ for x < 0.4 has no obvious preference for either tetrahedral or octahedral site but has a greater preference for the B site for x > 0.4. In nutshell the study presents detailed structural and magnetic, and Mossbauer analysis of Ni0.75Zn0.25Fe2-xAlO4 ferrites. (C) 2015 Elsevier Ltd. All rights reserved.