In this paper we report results of structural, spectroscopic, and magnetic investigations of ${\text{MgFe}}_2{\text{O}}_4$ nanoparticles prepared by soft mechanochemical synthesis. ${\text{MgFe}}_2{\text{O}}_4$ nanoparticles crystallize in $Fd\overline{3}m$ space group with mixed cation distribution and reduced percentage of ${\text{Fe}}^{3+}$ at tetrahedral (8a) sites. Discrepancy in the cation distribution compared to that in the bulk Mg–ferrite is one of the highest known. X-ray line broadening analysis reveals crystallite size and strain anisotropy. The saturation magnetization, $M_{\text{sat}}=62\text{emu}/\text{g}$ measured at 5 K is twice higher than that found in the bulk counterparts. Such high value of $M_{\text{sat}}$ is attributed to the low value of cation inversion parameter $\left(\delta =0.69\right)$ , to the core/shell structure of the nanoparticles and to the surface/volume ratio. Mössbauer spectrum collected at room temperature reveals ferrimagnetic ordering between ${\text{Fe}}^{3+}$ ions in $8a$ and $16d$ sites, while zero-field-cooled (ZFC) and field-cooled (FC) M(T) measurements were shown superparamagnetic state above 350 K.

Polyvinylalcohol/graphite nanocomposites with graphite nanosheets have been prepared by a mechanical method based on grinding of graphite powder, under low energy pure shearing milling, using water or KOH as lubricant. The use of different lubricant concurs to obtain graphite sheets that differently disperse in hydrophilic polymeric matrix. An improvement of water vapor permeability (up to 12%), compared with homopolymer, has been observed.

Herein we present the results of specific loss power (SLP) analysis of polydisperse water based ferrofluids, Fe₃O₄/PEG200 and Fe₃O₄/PEG6000, with average Fe₃O₄ particle size of 9 nm and 11 nm, respectively. Specific loss power was measured in alternating magnetic field of various amplitudes and at fixed frequency of 580.5 kHz. Maximum SLP values acquired were 195 W/g for Fe₃O₄/PEG200 and 60 W/g for Fe₃O₄/PEG6000 samples. The samples were labeled as superparamagnetic by magnetization measurements, but SLP field dependence showed deviation from the behavior predicted by the commonly employed linear response theory. The scope of this theory for both samples with wide particle size distribution is discussed. Deviation from the expected behavior is explained by referring to polydisperse nature of the samples and field dependent relaxation rates.