In this study, elastic properties of nanocrystalline Ni-Zn-Al ferrite synthesized by citrate-gel auto combustion method has been presented. X-ray diffraction and Infrared spectroscopy confirms the formation of spinel phase. Elastic properties are estimated from force constants and lattice constant determined from FTIR and XRD respectively. The observed variation of elastic constants has been interpreted in terms of strength of interatomic bonding and electronic configuration of the cations involved in the system. The average grain size has been observed to decrease with Al3+ substitution. A new antistructural modeling for describing of active surface centers is discussed. With this new anti structural modeling the changes in concentration of donor's active centers Ni'(B) and acceptor's active centers Fe-A(center dot) and Al-A(center dot) was explained. (C) 2018 Elsevier B.V. All rights reserved.