Vol.:(0123456789) 1 3 Applied Physics A (2018) 124:255 https://doi.org/10.1007/s00339-018-1672-8 Magnetic, hyperthermic and structural properties of zn substituted CaFe 2 O 4 powders Abbas Kheradmand 1  · Omid Vahidi 1  · S. M. Masoudpanah 2 Received: 31 July 2017 / Accepted: 9 February 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract In the present study, we have synthesized single phase Ca 1 − x Zn x Fe 2 O 4 powders by hydrothermal method. The cation distribu- tion between the tetrahedral and octahedral sites in the spinel structure and the magnetic properties as a function of the zinc substitution have been investigated by X-ray difraction (XRD), infrared spectroscopy and vibrating sample magnetometer methods. The obtained XRD pattern indicated that the synthesized particles had single phase cubic spinel structure with no impurity. The magnetic measurements showed that the saturation magnetization increased from 83 to 98 emu/g with the addition of zinc due to the decrease of inversity. The particle size observed by electron microscopy decreased from 1.38 to 0.97 µm with the increase of zinc addition. The Ca 0.7 Zn 0.3 Fe 2 O 4 powders exhibited appropriate heating capability for hyper- thermia applications with the maximum AC heating temperature of 20 °C and specifc loss power of 9.29 W/g. 1 Introduction Many studies in various felds have been focused on mag- netic spinel ferrites due to their unique physical and chemi- cal properties [1–4]. A unit cell of spinel ferrites with the generic formula of MFe 2 O 4 (where M represents a metal such as Fe, Co, Ni, Zn, Ca, etc.) comprises 32 oxygen atoms in cubic close packing structure possessing 8 tetrahedral (A) and 16 octahedral (B) occupied sites. Several factors includ- ing chemical composition, annealing temperature, cation distribution at tetrahedral (A) and octahedral [B] sites and synthesis method afect the spinel ferrites magnetic and elec- trical properties [5, 6]. Among spinel ferrites, calcium ferrite (CaFe 2 O 4 ) has received attentions for its suitable magnetic and electrical properties, remarkable chemical stability and biocompat- ibility making it an ideal material for oxidation catalysts, high-temperature sensors, gas absorbers, etc. [7, 8]. Calcium is inherently a non-toxic element which is safely metabo- lized by the body and its ferrite is capable to be used in biomedical applications [9]. The magnetic and electrical properties of calcium ferrite are efectively tunable by the substitution of the divalent/trivalent and magnetic/diamag- netic cations (e.g. Zn 2+ , Mg 2+ , etc.) [10] and are dependent on the amount of used cations. For instance, the addition of Zn 2+ manipulates the cation distribution in A and B sites. As zinc replaces calcium in the Ca 1 − x Zn x Fe 2 O 4 structure, Zn 2+ ions tend to occupy tetrahedral positions and subsequently, displace Fe 3+ in tetrahedral positions toward octahedral sites [11]. Nevertheless, since diferent ions compete in occupy- ing two sites, experimentation is required to determine the fnal cation distribution. Therefore, changing the cationic distribution and the chemical composition of the spinel fer- rites is a possible strategy to modulate the magnetic behavior because of the strong relationship between the spinel struc- ture and its magnetism [6]. Calcium ferrite nanoparticles can also be employed for biomedical applications such as magnetic separation, mag- netic resonance imaging, drug delivery and magnetic fuid hyperthermia [12]. In particular, magnetic fuid hyperther- mia is based on the ability of magnetic nanoparticles, when an alternate external magnetic feld is applied, to convert the electromagnetic energy into heat [10, 13]. Many eforts have been devoted to the optimization of the magnetic properties aimed to increase the heating ability and to reduce the nano- particle dose to be injected into the human body [14]. For this purpose, some studies investigated the enhancement of the saturation magnetization using alternative metal substi- tuted-ferrite nanoparticles [15, 16]. * Omid Vahidi ovahidi@iust.ac.ir 1 School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran 2 School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Tehran, Iran