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 γ-Fe 2 O 3 from the nanowires of α-Fe 2 O 3 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 γ-Fe 2 O 3 . The nanowires have a diameter ranging from 50 to 90 nm and their typical lengths are in the range of 10∼20 μm. 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 α-Fe 2 O 3 nanowires to γ-Fe 2 O 3 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 α-Fe 2 O 3 nanowires, and then α-Fe 2 O 3 is transformed into γ-Fe 2 O 3 .