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

Abstract

Polycrystalline Zn 1 -x Fe x O (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 Zn 1 -x Fe x (HCOO) 2 · 2H 2 O as a precursor. It has been found that the iron concentration in Zn 1 -x Fe x O 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 · 2H 2 O 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 Zn 1 -x Fe x O solid solutions regularly increases with an increase in the iron concentration. Based on the results of the X ray photoelectron spectroscopy analysis of Zn 1 ⎯ x Fe x O powders, it has been suggested that the iron concentration increases in the surface layer of parti cles, and the oxidation state of iron is 3+.