The recent development of the using the magnetic nanoparticles for hyperthermia treatments emphasizes the needed of smart materials to become a safety for heat therapy. Self-regulate magnetic nanoparticles of MnZnFe2O4 may be proper for thermal treatments. Structure and magnetic properties of the synthesis Mn1-xZnx Fe2O4 with x=0- 0.5 by step 0.1were studied. Superparamagnetic nanoparticles of MnZnFe2O4 were prepared by co-precipitation method, followed that heat treatment in the autoclave reactor. XRD results showed that is difficult to prepare MnZnFe2O4 directly using the co-precipitation method. Preparation method yield nanoparticles with spherical shape and there is a slight change in the particle size distribution, also observed shrinkage occurs in the particle size after heat treatments, the average particle size was estimated about 20nm as confirmed by FESEM images. FTIR spectra of samples showed two distinct absorption peaks in the range ~ 617 – 426 (cm-1) related to stretching vibrations of the (Fe-O) in the tetrahedral and octahedral side respectively. Magnetic measurements were carried out using (VSM), M-H curves indicate typical soft magnetic materials and particles so small to be identical superparamagnetic nanoparticles. Heating ability of water based colloidal dispersions of samples were studied under magnetic field strength 6.5kA/m and the frequency 190 kHz, and the results showed when increasing Zn2+ to x=0.3 or more the samples not heated up. Depending on the heating curve susceptibility, effective relaxation time and Néel relaxation time , were determined.

In the present work, the Ni-La ferrite chain (NiLa x Fe 2-x O 4) with (x=0.0-0.2),were synthesized using sol-gel auto-combustion as a modern chemical methods. Nitrates, citric acid and ammonia were used in order to get ferrite nano powders at temperature of (200) o C, which characterized a higher dispersion and homogeneity with particle size in the range of (20-39) nm. The dielectric properties are measured using (LCR) meter in the frequency range of (50Hz-5MHz). Dielectric constant (ε r '), the loss tangent (tanδ) and the loss factor (ε r ′′) are decreases with increasing frequency, while the Conductivity (ζ a.c) increases with increasing the rare earth ion (La) concentration in Ni ferrite.

In this work sol-gel method used for preparing nanoscale iron oxide ferrites dopant by copper and lithium, which carries the chemical formula Li 1-x Cu x Fe 5 O 8 where x is the added ratio as molar ratio (x = 0,0.1,0.2,0.3,0.4,0.5,0.6 and 1), during the self-combustion for sol-gel which happen at temperature of 200 o C, after that the samples were divided into four groups , the first group namely that have not been annealed while the other groups ; the second, third and fourth were annealed at 500 o C , 700 o C and 900 o C respectively. In this work the crystalline structure have a dominate phases which have been studied by using the X-ray diffraction as well as

NiZnMg-Ferrite Nano ceramics were prepared by using sol-gel auto combustion method, these ferrites then pelletized and sintered at different temperatures (1000, 1100 and 1200 0 C). Ferrite samples showed spinel structure and inherent properties of high electrical resistivity, low electrical losses and high theoretical densities. Therefore, these ferrites have a potential candidate for high frequency applications. The electrical and structural properties of Ni 0.7-y Zn 0.3 Mg y Fe 2 O 4 (where; y= 0, 0.1, 0.2 and 0.3) were studied and that shows an effect of chemical composition on the electrical, structural, and physical properties depending on Mg content in the Ferrite. Chemical phase analysis carried out by x-ray diffraction spectrum confirms the formation of ferrite Nanopowders with size (22.6 nm), and found that the lattice parameters and particle sizes increase, while theoretical density and porosity decreases with increasing of Mg content in the NiZnMg Ferrites. Resistivity of all samples has been measured at temperatures in the range of (300-540 K), which decreases with increasing of temperatures like a semiconductor behavior.

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