Studies of the properties of ZnxFe3-xO4 (x=0, 0.25, 0.5, 0.75, 1.0) magnetic nanoparticles synthesized by a modified hydrothermal method are presented in comparison with the properties of the same nanoparticles stabilized with polyacrylic acid ZnxFe3-xO4@PAA. The structure, size, morphology, and magnetic properties of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), physical properties measurements (PPMS), and Mossbauer spectroscopy. The synthesized nanoparticles are single-phase, without additional impurities, have a narrow size distribution and are in the superparamagnetic phase. From the (XRD) measurements, it was found that with an increase in the Zn content from x=0 to x=1.0, the sizes of the nanoparticles were increasing from 17 to 33 nm. Analysis of the Mossbauer spectroscopy data showed that when doped with Zn ions from x=0 to x=1.0, the sizes of the nanoparticles were decreasing from 15 nm to 5 nm. The results of the Mossbauer studies showed that both ZnxFe3-xO4 and ZnxFe3-xO4@PAA has a core/shell type structure in which the core is magnetically ordered, whereas the shell does not have magnetic ordering. Mossbauer studies indicate that the coating of citric acid particles leads to their isolation from each other (i. e., a decrease in the thickness of the paramagnetic shell, and due to this to increasing in the diameter of the core). This (the last sentense) sentense is too long. It could be mode two or three sentences for better clarification. Keywords: ferrite-spinel nanoparticles, hydrothermal synthesis, polyacrylic acid functionalization, Mossbauer spectroscopy, properties, crystal and magnetic structure.

The effect of surface functionalization with citric acid on the properties of magnetic nanoparticles (MNPs) ZnxFe3-xO4 (x=0; 0.25; 0.5; 0.75; 1.0) synthesized by the hydrothermal method was studied. To study the properties of MNPs, X-ray diffractometry (XRD) and energy dispersive X-ray spectroscopy (EDS) were used. The magnetic properties of the samples and the phase state of MNPs were studied using a physical property measurement system (PPMS) and Mossbauer spectroscopy (MS). It has been established that the sizes of crystallites and the crystal lattice parameter of ZnxFe3-xO4 MNPs change with increasing Zn2+ concentration. The low values of the coercive force and the presence of a doublet on the MS indicate the presence of both ferrimagnetic and superparamagnetic components. Keywords: ZnxFe3-xO4 ferrite spinel MNPs, hydrothermal synthesis, functionalization of MNPs with citric acid, crystal structure, magnetic properties, magnetic structure.

Studies of the properties of ZnxFe3-xO4 (x=0, 0,25, 0,5, 0,75, 1) magnetic nanoparticles synthesized by a modified hydrothermal method are presented in comparison with the properties of the same nanoparticles stabilized with polyacrylic acid ZnxFe3-xO4@PAA. The structure, size, morphology, and magnetic properties of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), physical properties measurements (PPMS), and Mossbauer spectroscopy. The synthesized nanoparticles are single-phase, without additional impurities, have a narrow size distribution and are in the superparamagnetic phase. From the RD measurements, it was found that with an increase in the Zn content from x = 0 to x= 1.0, the sizes of nanoparticles increasing from 17 to 33 nm. Analysis of the Mössbauer spectroscopy data showed that when doped with Zn ions from x=0 to x=1.0, the sizes of nanoparticles decreasing from 15 nm to 5 nm. The results of the Mossbauer studies showed that both ZnxFe3-xO4 and ZnxFe3-xO4@PAC has a core/shell type structure in which the core is magnetically ordered, whereas the shell does not have magnetic ordering. Mossbauer studies indicate that the coating of citric acid particles leads to their isolation from each other, a decrease or elimination of interactions between particles, a decrease in the thickness of the paramagnetic shell, and, due to this, an increase in the diameter of the core.