Mn-Doped In2O3 Nanoparticles: a Simple Synthesis and Room-Temperature Ferromagnetism

In this research, Mn-doped In2O3 nanoparticles were successfully synthesized by a simple thermal decomposition method using indium acetate and manganese acetate tetrahydrate as the starting materials. The precursor was characterized by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) to obtain the thermal decomposition and crystallization temperature. The precursor was calcined at 500–600∘C in air for 2 h to obtain nanoparticles of In2O3 and Mn-doped In2O3. The phase composition of calcined samples was studied by X-ray diffraction (XRD). The XRD results confirmed the formation of In2O3 phase with cubic structure. The particle sizes of the samples were found to be 12–22 nm as evaluated by the X-ray line broadening method. The corresponding selected area electron diffraction analysis further confirmed the formation of the cubic structure of In2O3 without any impurity phases. The optical properties of the samples were investigated by optical absorption. The estimated band gap of the samples was in the range of 3.30–3.45 eV. X-ray photoelectron spectroscopy was performed and played an important role to confirm and understand in terms of qualitative In and Mn oxidation states causing a ferromagnetic properties in the Mn-doped In2O3 sample. Room-temperature ferromagnetism was investigated by a vibrating sample magnetometer. The undoped samples exhibit a diamagnetic behavior, whereas the Mn-doped In2O3 samples are ferromagnetic, having the magnetizations of 0.25–0.62 memu/g at 15 kOe. Successful synthesis of Mn-doped nanoparticles with room-temperature ferromagnetism was of great importance in both technological and theoretical aspects.