Top-down synthesis of mesocrystalline [alpha]-Fe2O3 submillimeter-sized rhombohedrons

• Published in: Particulate science and technology Vol. 34; no. 5; p. 571
• Main Authors: Kiss, Mihaela Luminita, Chirita, Marius, Ieta, Adrian, Sacarescu, Liviu, Savii, Cecilia
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Ltd 01.09.2016
• Subjects: Chemical synthesis; Nanoparticles; Scanning electron microscopy
• ISSN: 0272-6351; 1548-0046
• DOI: 10.1080/02726351.2015.1090508

Here, we focus on the obtaining of mesocrystalline submillimeter-sized (150/50 µm) rhombohedral hematite (α-Fe2O3) by thermal treatment in air of single crystalline submillimeter-sized (150/50 µm) rhombohedrons of ferrous carbonate (FeCO3). Mass spectrometer-coupled thermogravimetric analysis and TGA-MS revealed the chemical reactions occurring during the thermal treatment of ferrous carbonate sample. The X-ray Diffraction (XRD) data sustain that the final product is hematite. The XRD line-profile analysis indicates that the resulted hematite is built of individual ordered crystallites with 66 ± 5 nm average sizes, confirmed by scanning electron microscopy and transmission electron microscopy images. Small-angle x-ray scattering investigation of hematite sample was presented. The log-log plot of scattering intensity decay showed the same slope, α = -3.76, corresponding to both high and low scattering vector regions; the fractal surface is Ds = 2.24. This fractality is extended over a range of sizes and can touch high molecular dimensionality. The internal morphology and the synthesis mechanism of the obtained hierarchical superstructure were described.