Structural and magnetic properties of the Zn0.8-4xHoxOy (0.05 ≤ x ≤ 0.10) compounds prepared by solid state reactions

Zn0.8-4xHoxOy (0.05 <= x <= 0.10) diluted magnetic semiconductors were prepared by the solid state reaction method. We have studied the structural properties of the samples by using the XRD, SEM, and EDX techniques. The SEM results clearly demonstrate that Ho3+ ions are quite well substituted for Zn2+ in the ZnO lattice, and the grains of the samples are very well connected to each other and tightly packed. From the XRD and EDX spectra of the samples, it has been concluded that the substitution of Ho causes no change in the hexagonal wurtzite structure of ZnO. According to our M-H and M-T measurements paramagnetism has been observed for all the samples from our attainable lowest temperature of 10 K to 300 K. Furthermore, the trend of the AC-susceptibility (chi) versus temperature curves, measured under an AC-magnetic field of 10 Oe, also support our conclusion about the paramagnetic contribution in the Zn0.8-4xHoxOy compounds explored in this study. In order to clearly see the paramagnetic contribution, and whether there is also a ferromagnetic or antiferromagnetic contribution or not the inverse susceptibility (1/chi) against temperature curves are also plotted. Those curves indicate that, the substitution of Ho into the ZnO compound causes, in addition to the paramagnetism, a weaker antiferromagnetic (AFM) interaction. (C) 2012 Elsevier Masson SAS. All rights reserved.