Growth and properties of single-crystalline γ-Fe2O3 nanowires

By carefully controlling the reacting conditions, including atmosphere, temperature, and time, we directly acquire the nanowires of gamma-Fe2O3 from the nanowires of alpha-Fe2O3 in a reduced atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectrum, and transmission electronic microscope analyses demonstrate that the nanowires are single-crystalline gamma-Fe2O3. The nanowires have a diameter ranging from 50 to 90 nm and their typical lengths are in the range of 10 similar to 20 mu m. The optical property of the nanowires is observed by photoluminescence spectrum. The magnetic behavior of it is investigated by a magnetic property measurement system. The blocking temperature is found to be about 200 K. In addition, the mechanism of the transformation from alpha-Fe2O3 nanowires to gamma-Fe2O3 nanowires is preliminarily studied by ab initio approach. It is found that the role of H-2 is to change the Fe-O bonds in alpha-Fe2O3 nanowires, and then alpha-Fe2O3 is transformed into gamma-Fe2O3.