Sol–gel synthesis, structure and magnetic properties of Mn-doped ZnO diluted magnetic semiconductors

2.5, 5, 10 and 15% Mn-doped ZnO diluted magnetic semiconductors (DMSs) were prepared via an ethyl acetoacetate-aided sol–gel process. The 5% Mn-doped ZnO consists of 20–50 nm spheroid-like particles and has a wurtzite phase. Existence of nanoscale ZnMnO3 clusters in this sample is confirmed by HRTEM analysis. Vegard's law calculation reveals that about 2.6% Mn atoms have been incorporated into ZnO lattice. Besides major wurtzite phase, ZnMnO3 secondary phase is observed in the 10% and 15% Mn-doped samples. The Mn-doped ZnO shows red shift of photoluminescence (PL), which arises from defects caused by Mn incorporation. The magnetic measurements confirm that the 2.5% and 5% Mn-doped ZnO samples display room-temperature ferromagnetism as well as paramagnetism, while the 10% and 15% samples exhibit paramagnetic effects. The as-observed ferromagnetic behaviors likely originate from cooperative effect of intrinsic and extrinsic magnetisms.

► Mn doped ZnO were prepared using an ethyl acetoacetate aided sol-gel process.
► With addition of ethyl acetoacetate to aqueous ethanol, a stable sol was obtained.
► The 5% sample consists of spheroid-like particles with size of 20–50 nm.
► The 2.5% and 5% samples exhibits room-temperature ferromagnetism and paramagnetism.
► The 10% and 15% samples exhibit large paramagnetic effects.