Structural and magnetic properties of Zn1−xMnxO (≤x≤0.40) nanoparticles

Abstract

${\text{Zn}}_{1-x}{\text{Mn}}_x\text{O}$ nanoparticles synthesized by a combustion method with Mn concentration $x$ up to 0.40 are carefully characterized by means of x-ray powder diffraction and high resolution transmission electron microscopy. Single-phase solid solution ${\text{Zn}}_{1-x}{\text{Mn}}_x\text{O}$ is achieved with a solubility limit of $\sim 30\text{at}.\%$ Mn. An almost linear dependence of lattice constant on the Mn content is observed, indicating the homogeneous substitution of ${\text{Mn}}^{2+}$ for the ${\text{Zn}}^{2+}$ in wurtzite ZnO. Magnetization at $T=5\text{K}$ and $H=5\text{T}$ exhibits a maximum around the Mn doping concentration of $x_m=0.125$ . Room temperature ferromagnetism with low coercive field $\left({\text{H}}_c\sim 70\pm 5\text{Oe}\right)$ is obtained for the sample with $x=0.01$ . The observed magnetic properties of ${\text{Zn}}_{1-x}{\text{Mn}}_x\text{O}$ can be well understood within the framework of the donor impurity band exchange model.