Influence of addition of Al 3þ on the structural and solid state properties of nanosized NieZn ferrites synthesized using malic acid as a novel fuel Prajyoti P. Gauns Dessai a , Sher Singh Meena b, ** , V.M.S. Verenkar a, * a School of Chemical Sciences, Goa University, Taleigao Plateau, Goa, 403206, India b Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India article info Article history: Received 8 April 2020 Received in revised form 24 May 2020 Accepted 28 May 2020 Available online 3 June 2020 Keywords: NieZneAl-Ferrites Combustion synthesis Cation distribution M€ ossbauer Magnetic properties FC-ZFC curves abstract In this work, the synthesis of Ni 0.7 Zn 0.3 Fe 2-x Al x O 4 (x ¼ 0.0e0.6) nanoferrites by combustion method using malic acid as a novel fuel is being reported for the first time. The structural analysis of the nanosized ferrites was carried out by using XRD and IR studies. The cation distribution of all the ferrites was predicted using the Rietveld refinement data and was well supported by the M€ ossbauer analysis. The XRD parameters were calculated using this predicted cation distribution. The theoretical lattice constant matched exactly with the lattice constant obtained from the Rietveld refinement confirming the pre- dicted cation distribution. The morphology of all the ferrites was studied using the SEM microscopy from which the particle size distribution was calculated along with the EDS mapping which confirmed the presence of all the constituent elements in all the ferrite samples. The dielectric properties of all the ferrites as a function of frequency as well as temperature were studied. The influence of substitution of magnetic Fe 3þ by non-magnetic Al 3þ in the ferrite series was also studied. It was observed that the addition of non-magnetic Al 3þ in ferrites decreases the lattice parameter, density, saturation magneti- zation, and the Curie temperature. The FC-ZFC magnetization curve revealed a decrease in blocking temperature (T B ) with an increase in Al 3þ concentration in Ni 0.7 Zn 0.3 Fe 2-x Al x O 4 . © 2020 Elsevier B.V. All rights reserved. 1. Introduction Nowadays, research in nanotechnology has touched almost all the fields, simply because nanomaterials are found to show extraordinary properties compared to its bulk counterparts and find applications in many fields [1]. And if the nanomaterial is of spinel ferrite type having general formula AB 2 O 4 which is commercially important class of materials, then it won’t be sur- prising that nanoparticles research of these ferrites will generate an enormous interest amongst the researchers. Spinel ferrites exhibits the Cubic close packed structure in which the large oxygen ions forms an FCC lattice. Two interstitial sites are present in this Cubic lattice namely, the tetrahedral (A) site and the octahedral (B) site. Depending upon the distribution of cations, bivalent and trivalent cations in these sites, the spinel ferrites are classified as the normal, inverse and random spinels [2,3]. The nickel zinc ferrites among the spinel ferrites have been synthesized and characterized extensively because of their huge technological applications which are due to their high permeability at high frequency, low eddy current loss and high resistivity [1 ,3e6]. It is a well-known fact that when a magnetic ferrite is diluted with a non-magnetic ion it can alter the electrical and magnetic properties of the system. For example, substitution of Fe 3þ by Al 3þ ions in NieZn ferrites increases re- sistivity, lowers the dielectric losses and decreases the saturation magnetization thereby altering the magnetic and electrical prop- erties of the material [4,7]. Besides this, few other factors which are known to change the properties of a material are the method of preparation, the fuel used (especially, if the method of preparation is precursor combustion or combustion method) and the sintering temperature with time [8e10]. Although there are many reports available in general on aluminium substituted NieZn ferrites, very few reports are available specifically on aluminium substituted Ni 0.7 Zn 0.3 Al x Fe 2-x O 4 system [7 , 11e 16]. It has been also observed * Corresponding author. School of Chemical Sciences, Goa University, Taleigao Plateau, Goa, 403206, India. ** Corresponding author. Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India. E-mail addresses: ssingh@barc.gov.in (S.S. Meena), vmsv@rediffmail.com (V.M.S. Verenkar). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2020.155855 0925-8388/© 2020 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 842 (2020) 155855