T. V. Dyachkova

Observation of ferromagnetism at room temperature in polycrystalline Zn1 − x Fe x O solid solutions synthesized by the precursor method

Polycrystalline Zn1 − xFexO (0 ≤ x ≤ 0.075) solid solutions with the wurtzite structure, which belong to the class of diluted magnetic semiconductors, have been synthesized by the precursor method using a mixed formate of the composition Zn1 − xFex(HCOO)2 · 2H2O as a precursor. It has been found that the iron concentration in Zn1 − xFexO solid solutions, which exhibit ferromagnetic properties with a high degree of magnetization at room temperature, is determined by two factors: (1) the degree of substitution of iron for zinc in the structure of zinc formate Zn(HCOO)2 · 2H2O and, therefore, in the structure of zinc oxide ZnO and (2) the conditions of heat treatment of the precursor. It has been shown using samples with x = 0.025 and 0.05 as an example that the magnetization of Zn1 − xFexO solid solutions regularly increases with an increase in the iron concentration. Based on the results of the X-ray photoelectron spectroscopy analysis of Zn1 − xFexO powders, it has been suggested that the iron concentration increases in the surface layer of particles, and the oxidation state of iron is 3+.

Synthesis and magnetic properties of nanocrystalline Zn1–xFexO solid solutions

Zn1–xFexO nanocrystalline solid solutions (x = 0, 0.025, 0.05) with wurtzite structure and ferromagnetic properties at room temperature are synthesized for the first time using mixed formate of Zn1 - xFex(HCOO)2 · 2H2O composition as a precursor. It is shown that the magnetization of Zn1–xFexO solid solutions rises along with the iron concentration.

Structure of the monoclinic modification of Re3B

By powder X-ray diffraction the structure of the monoclinic modification of Re3B is studied. The phase is obtained under high pressure and high temperature (10 GPa, 1800°C) using nanocrystalline rhenium and amorphous boron. The results of the comparative crystal chemical analysis are reported.