In Mansour et al., 2017, it is told that various methods (sol-gel, thermal decomposition, ionic liquidassisted synthesis, hydrothermal method, co-precipitation method, polyol) exist to prepare α-Fe2O3 nanoparticles. Moreover, hematite particles were also prepared by means of the precipitation of β-FeOOH. Mansour and coworkers used two methods: (1) polyol and (2) precipitation in water. "The influence of synthesis methods on the crystalline structure, morphological, optical, magnetic and electrical properties were investigated", using the Raman spectroscopy too. In the Figure by Mansour et al., we can find the peaks as given in the previous page.