Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-017-8504-z Tailoring magnetic and dielectric properties of Co 0.9 Cu 0.1 Fe 2 O 4 with substitution of small fractions of Gd 3+ ions Chandan C. Naik 1  · A. V. Salker 1 Received: 15 November 2017 / Accepted: 29 December 2017 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract This paper describes the structural, magnetic, and dielectric properties of Gd 3+ substituted cobalt–copper ferrite. The infu- ence of Gd 3+ substitution on the structural, magnetic and electrical properties of cobalt–copper ferrite was investigated through various characterization techniques. Thermal analysis was carried out on the prepared gel to know the combustion and calcination temperature. The detailed structural analysis suggests that the substitution of a Fe 3+ ion with a Gd 3+ ion at B site results in lattice distortion, modifcation in crystallite size and grain size of the material. X-ray photoelectron spec- troscopy confrmed the oxidation states of the elements present. Magnetic measurement performed at 300 and 50 K depicts the decrease in saturation magnetization (Ms) and increase in coercivity (Hc) with Gd 3+ substitution in the cobalt–copper spinel ferrite. The dielectric measurements acquired over a wide range of frequencies and temperature showed an increase in dielectric constant with increasing Gd 3+ concentration. 1 Introduction Over the past two decades, the enormous emphasis has been given on development and modulation of the existing materi- als with the fabrication of novel materials having extensive applications. Since the magnetic spinel ferrites are highly stable, sustainable and economical they can be utilized in various felds. Recently magnetic spinel ferrite nanoparticles have engrossed considerable attention due to their potential applications in high-density magnetic recording, magnetic fuids, microwave devices, sensors, spintronics, data stor- age, switch mode power supplies, catalysis and biological tagging [1–9]. Cobalt ferrite has received pronounced scientifc atten- tion because of its fascinating properties and remarkably promising applications. It is considered to have interesting magnetic properties since it has high coercivity, moderate saturation magnetization with a high Curie temperature. The notable magneto-striction property of cobalt ferrite is because of its high positive magneto-crystalline anisotropy, due to the spin–orbit coupling of Co 2+ ions positioned at the octahedral sites (B site) of the spinel lattice [10]. Several fabrication routes have been explored for the preparation of pristine and substituted CoFe 2 O 4 , such as co-precipita- tion, sol–gel, combustion, hydrothermal etc [5, 11–13]. The method of preparation and heat treatment given to the sam- ple has an enormous impact on the grain size of the prepared ferrite, which in turn determines its properties. Furthermore, the properties of cobalt ferrite can be modifed by various chemical alterations such as replacing one or more ions from the lattice with transition metal ions or rare earth metal ions and by changing the reaction conditions. The modifcations in several properties of cobalt ferrite are anticipated with the incorporation of divalent metal ions like Cu 2+ , Ni 2+ and Zn 2+ ions, making it an apt candidate for sensors, catalyst and in biomedical application. Recently Joshi et al. reported the enhancement in gas sensing prop- erties of cobalt ferrite with nickel substitution [14]. Sanpo et al. investigated the efect of copper substitution on cobalt ferrite nanoparticles for biomedical applications [8]. Also, Hankare et al. studied the efect of copper substitution on cobalt ferrite as a catalyst for the selective oxidation of alco- hol [15]. The lower coercivity of spinel ferrites is a major obstacle that considerably limits their usage in high-density magnetic Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10854-017-8504-z) contains supplementary material, which is available to authorized users. * A. V. Salker sal_arun@redifmail.com 1 Department of Chemistry, Goa University, Goa, Goa 403206, India