Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom Study of structural, vibrational, elastic and magnetic properties of uniaxial anisotropic Ni-Zn nanoferrites in the context of cation distribution and magnetocrystalline anisotropy Ch. Srinivas a, ⁎ , M. Deepty a , S.A.V. Prasad a , G. Prasad a , E. Ranjith Kumar b, ⁎ , Sher Singh Meena c , Naidu V. Seetala d , Darnel D. Willams d , D.L. Sastry e, ⁎ a Nanomaterials and Nanomagnetism Research Laboratory, Department of Physics, Sasi Institute of Technology & Engineering, Tadepalligudem 534101, India b Department of Physics, KPR Institute of Engineering and Technology, Coimbatore 641047, Tamil Nadu, India c Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India d Department of Mathematics & Physics, Grambling State University, Grambling, LA, USA e Department of Physics, Andhra University, Visakhapatnam 530003, India article info Article history: Received 23 February 2021 Received in revised form 23 March 2021 Accepted 30 March 2021 Available online 6 April 2021 Keywords: Thermodynamical stability, Cation redistribution Vibrational frequencies Elastic moduli Magnetocrystalline anisotropy abstract Co-precipitation method was adopted to obtain zinc ferrite nanoparticles substituted with nickel (0.5 ≤ x ≤ 0.7) followed by sintering at 500 °C for 2 h. The formation of spinel ferrite phase in the present ferrite compositions was confrmed from the X-ray diffractograms. The experimental lattice parameter (a) and average crystallite size (< D XRD >) are in between 8.359 - 8.348 Å and 12.8 – 14.9 nm. As doping level of Ni 2+ increases, an interesting relation was existed in between a and < D XRD > , such that the frst one is decreasing and the later one is increasing. The variation of average particle size (< D FE-SEM >) from FE-SEM is different from the variation of < D XRD > . The present spinel ferrite Ni 0.6 Zn 0.4 Fe 2 O 4 possessed smaller particle size of 17.6 nm. The existence of higher and lower vibrational frequencies in between 579–587 cm −1 and 380–386 cm −1 , satisfed the Waldron proposals for the ferrite phase. The variations of elastic moduli are very interesting and tricky when compared to the reported literature. The consistency of Poisson’s ratio for these ferrite compositions, revealed the isotropic behavior of present ferrite systems. The saturation magnetization (M S ) at room temperature (RT) has uneven variation and a highest value of 43.2 emu/g was noticed for the composition x = 0.6. The coercivity (H C ) at RT is gradually increasing with the doping level of Ni 2+ ion incorporation. As temperature is decreasing below the room temperature both the M S and H C are increasing for a particular composition. The blocking temperature (T B ) lies in the range of 80–125 K and is increasing with the increase of Ni 2+ ion concentration. The fndings of the present study were discussed in terms of cation distribution and magnetocrystalline anisotropy presuming core-shell morphology. © 2021 Elsevier B.V. All rights reserved. 1. Introduction The size dependent properties of ferrites under nanoscale me- trics make them exceptional due to their abundant multi dis- ciplinary utility [1,2]. Spinel ferrites are represented as ( + + M Fe x x 1 2 3 ) [ + + M Fe x x 2 2 3 ]O 4 (where M 2+ = Ni 2+ , Zn 2+ , Mn 2+ , Mg 2+ , etc. is a divalent metal ion). The metal ions occupied in the tetrahedral (A) interstitial space are shown in parentheses and the metal ions occupied in the octahedral (B) interstitial space are shown in square brackets [3]. In the above formula unit for x = 1, the spinel structure ( + Fe 1 3 )[ + + M Fe 1 2 1 3 ] O 4 is an inverse spinel ferrite ( eg: NiFe 2 O 4 is an inverse spinel having a = 8.339 Å, JCPDS-74-2081 and M S = 55.4 emu/g) and for x = 0, the spinel structure ( + M 1 2 )[ + Fe 2 3 ]O 4 is a normal spinel ferrite (eg: ZnFe 2 O 4 is a normal spinel having a = 8.416 Å, JCPDS-77-11 and M S = 0 emu/g) [4]. The substitution of Ni 2+ for Zn 2+ /Zn 2+ for Ni 2+ in the spinel structure leads to mixed spinel structure with the formula unit Ni x Zn 1–x Fe 2 O 4 /Ni 1–x Zn x Fe 2 O 4 . The study of different solid state properties of Ni–Zn ferrite nanoparticles even today is very inter- esting due to their versatile behaviors like, chemical stability, me- chanical hardness, high saturation magnetization, low coercivity, etc. [5]. Different studies have been reported for Ni–Zn nanoferrites as well as different dopants substituted Ni–Zn nanoferrites synthesized https://doi.org/10.1016/j.jallcom.2021.159748 0925-8388/© 2021 Elsevier B.V. All rights reserved. ]] ]] ]]]]]] ⁎ Corresponding authors. E-mail addresses: srinivas.chintoju75@gmail.com (C. Srinivas), ranjueaswar@gmail.com (E.R. Kumar), dl_sastry@rediffmail.com (D.L. Sastry). Journal of Alloys and Compounds 873 (2021) 159748