Influence of Fe-Doping on the Structural and Magnetic Properties of ZnO Nanopowders, Produced by the Method of Pulsed Electron Beam Evaporation

Abstract

The nanopowders (NPs) ZnO-Zn-Fe and ZnO-Fe with the various concentrations of Fe (xFe) (0≤xFe≤0.619mass.%) were prepared by the pulsed electron beam evaporation method. The influence of doping Fe on structural and magnetic properties of NPs was investigated. X-ray diffraction showed that powders contain fine-crystalline and coarse-crystalline ZnO fractions with wurtzite structure and an amorphous component. Secondary phases were not found. The magnetic measurements made at room temperature, using the vibration magnetometer and Faraday’s scales, showed ferromagnetic behavior for all powders. Magnetization growth of NPs ZnO-Zn and ZnO-Zn-Fe was detected after their short-term annealing on air at temperatures of 300–500°C. The growth of magnetization is connected with the increase in the concentration of the phase ZnO with a defective structure as the result of oxidation nanoparticles (NPles) of Zn. The scanning transmission electron microscopy (STEM) showed a lack of Fe clusters and uniform distribution of atoms dopant in the initial powder ZnO-Zn-Fe. A lack of logical correlation between magnetization and concentration of a magnetic dopant of Fe in powders is shown.

Bimodal Fucoidan-Coated Zinc Oxide/Iron Oxide-Based Nanoparticles for the Imaging of Atherothrombosis

“…Compared with the other preparations, the additional signal between 46° and 53°, which corresponds to an indexation (400) of the cubic phase, made it possible to conclude that the two Zn 0.54 (Fe) 0.46 O and ZnFe 2 O 4 phases were mixed with a molar proportion determined by refinement of 2.57: 1. In previous works using polyol method the NPs sizes were higher than those obtained in our study: Balti et al: 17 nm [ 20 ], Dinesha et al: 19–34 nm [ 21 ], Ciciliati et al: 11–25 nm [ 31 ], Il’ves et al: 10–20 nm [ 13 ] and Arciniegas-Grijalba et al: 20–35 nm [ 32 ]. Moreover, irrespective of the synthesis method, other studies have observed that the size of Zn(Fe)O NPs decreased with the increase of iron concentration and they noted also the formation of a secondary phase-spinel ZnFe 2 O 4 increasing with the concentration of Fe doping and with the annealing temperature [ 13 ].…”

“…In previous works using polyol method the NPs sizes were higher than those obtained in our study: Balti et al: 17 nm [ 20 ], Dinesha et al: 19–34 nm [ 21 ], Ciciliati et al: 11–25 nm [ 31 ], Il’ves et al: 10–20 nm [ 13 ] and Arciniegas-Grijalba et al: 20–35 nm [ 32 ]. Moreover, irrespective of the synthesis method, other studies have observed that the size of Zn(Fe)O NPs decreased with the increase of iron concentration and they noted also the formation of a secondary phase-spinel ZnFe 2 O 4 increasing with the concentration of Fe doping and with the annealing temperature [ 13 ]. Surprisingly, TEM evidenced a unique population of NP-0.50 with an average size of 4.2 ± 0.6 nm in accordance with the sizes of the crystallites determined by XRD ( Table 1 ).…”

“…We hypothesize that for this time, nucleation occurred but the growth of wurtzite crystals was very limited by the rapid removal of water molecules. The formation of other secondary phases, such as Fe 3 O 4 , could also be observed which was not the case in our study, likely due to the relatively low temperature of the polyol medium as compared to much higher annealing temperatures needed to induce the formation of Fe 3 O 4 [ 13 ].…”

“…In addition to luminescence properties related to quantum size effect, the Fe-doping ZnO NPs (Zn(Fe)O) would allow for the consideration of dual MR and optical bimodal imaging. Zn(Fe)O have been synthesized by many ways [ 13 ], the most popular approach being the polyol method [ 14 ] which makes it possible to solubilize a large number of metallic precursors and to efficiently activate the reactions favoring particles with a high crystallinity and a narrow size distribution [ 15 , 16 ] and Fe 3 O 4 @ZnO [ 17 , 18 ], and ZnO nanorods decorated with γ-Fe 2 O 3 have been proposed [ 19 ]. The formation of Zn(Fe)O nanocrystals without modification of the elementary cell, i.e., leading to the same crystal lattice, could be obtained either by substitution of some zinc ions by iron ions, or by the inclusion of iron ions into tetrahedral sites of the hexagonal wurtzite cell [ 20 , 21 ].…”

Magnetic and Photoluminescent Coupling in SrTi0.87Fe0.13O3−δ/ZnO Vertical Nanocomposite Films

“…This would not be detectable from XRD because Fe 2+ substituting for Zn 2+ leads to only a small increase of the ZnO lattice parameter of ∼0.01 Å for ∼10 atom % Fe 2+ substitution . We note that any Fe present in the ZnO could contribute to the magnetization of the nanocomposite, but the reported magnetization of Fe in ZnO varies widely. − …”