Abstract
In the original version, all the peaks are indexed in all figures expect the two small peaks at 72.08 and 75.54 degrees; they are assigned to the diffraction plane of the hematite phase (1010) and (220) (JCPDS card number 00-001-1053). The peaks located at 71.5 and 74.5 degrees are assigned to the diffraction plans (620) and (533) of the spinel phase, respectively.