Phase control and enhanced gas sensing properties of metastable ϵ-Fe₂O₃

ABSTRACT

Different phase structures (α-Fe₂O₃, γ-Fe₂O₃ and ϵ-Fe₂O₃) of iron oxides (Fe₂O₃) were prepared by the same method- a combination method of reverse-micelle and sol-gel. The phase structures were controlled by adding different ionic additives (Na⁺ and Ba²⁺). The as-synthesized α-Fe₂O₃, γ-Fe₂O₃ and ϵ-Fe₂O₃ samples were investigated and discussed using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and an intelligent gas sensing analysis system. Interestingly, metastable ϵ-Fe₂O₃ showed an excellent selectivity for n-butanol, compared with the stable phases of α-Fe₂O₃ and γ-Fe₂O₃. It indicates that nanostructure ϵ-Fe₂O₃ could be a valuable material for the fabrication of advanced sensing devices.

KEYWORDS:

• ϵ-Fe₂O₃
• Fe₂O₃
• phase control
• gas sensing
• reverse-micelle
• sol-gel method

Additional information

Funding

The authors are grateful for financial support from the National Natural Science Foundation of China (grant nos. 51172157 and 51202159).