Structure and magnetic properties of coprecipitated nickel-zinc ferrite doped rare earth elements of Sc, Dy, and Gd

Abstract

This research is the basic study of temperature-sensitive ferrite characteristics prepared by coprecipitation with doping different typical sizes of rare earth elements. Ni 0.5 Zn 0.5 Re x Fe 2-x O 4 (NZRF) (X = 0.02, 0.05, 0.07 and 0.09) nanoparticles (NPs) doped by Sc, Dy and Gd prepared by chemical coprecipitation method. The structure and properties of Ni 0.5 Zn 0.5 Re x Fe 2-x O 4 were analyzed by various characterization methods. XRD results show that the grain size of Ni 0.5 Zn 0.5 Re x Fe 2-x O 4 is from 10.6 to 12.4 nm, which is close to the average grain size of 13.9 nm observed on TEM images. It is also found that the ferrite particles are spherical and slightly agglomerated in TEM images. FTIR measurements between 400 and 4000 cm -1 have confirmed the intrinsic cation vibration of the spinel structure. The concentrations of nickel, zinc, iron, and rare earth elements have been determined by ICP-AES, and all ions have participated in the reaction. The magnetic properties of Sc, Dy, and Gd 3+ doped NZRF NPs at room temperature are recorded by a physical property measurement system (PPMS-9). It is found that the magnetization can be changed by adding rare-earth ions. When X = 0.07, Gd 3+ doped Ni 0.5 Zn 0.5 Fe 2 O 4 (NZF) exhibits the highest saturation magnetization. The magnetic properties of NZGd 0.07 vary the most with temperature. The thermomagnetic coefficient of NZGd 0.07 nanoparticles stabilized to 0.18 emu/gK at 0-100℃. Hence, NZGd 0.07 with low Curie temperature and the high thermomagnetic coefficient can be used to prepare temperature-sensitive ferrofluid. All the samples exhibit very small coercivity and almost zero remanences, which indicates the superparamagnetism of the synthesized nanoparticles.

A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy

“…The examples mentioned above and more in literature [290,291] prove the importance of GBs and HIs in magnetic behavior of oxides, and therefore highlight the importance of their characterization.…”

“…Figure 41 represents the BF-TEM image of Mn-doped ZnO films with (a) 10 and (b)15 at% Mn concentration. The direct resolution of the lattice allows the observation of the crystalline ZnO grains in wurtzite structure, and it is clearly visible that amorphous phases lie at the areas between the grains or in other words, GBs[289].The examples mentioned above and more in literature[290,291] prove the importance of GBs and HIs in magnetic behavior of oxides, and therefore highlight the importance of their characterization.…”