Study on emission spectral lines of hematite and magnetite for purity’s differentiation

Maurizio Manzo,Seifollah Nasrazadani,Hossain Ahmed

doi:10.1063/1.5143413

Maurizio Manzo, Seifollah Nasrazadani + Show 1 more

Open Access

https://doi.org/10.1063/1.5143413

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Journal: AIP Advances	Publication Date: Oct 1, 2020
Citations: 14	License type: cc-by

Affiliation: University of North Texas

Abstract

Iron oxides have been investigated by employing mostly Fourier-transform infrared spectroscopy (FTIR). However, absorption spectra sometimes are difficult to obtain in situ, where accessibility to the location is limited. In this paper, we propose using emission spectra to investigate the purity of hematite (α-Fe2O3) and magnetite (Fe3O4). We used an infrared beam (wavelength of 1064 nm) from a pulsed laser to obtain emission spectra of the α-Fe2O3 and Fe3O4 for two different purities (99.99% and 96%) ranging from visible to near-infrared regions. The average values of full width at half maximum (FWHM) for the 99.99% purity were found to be 0.15 nm and 0.17 nm for the hematite and the magnetite, respectively; the average values of FWHM for the 96% purity were found to be 0.19 nm and 0.23 nm for the hematite and the magnetite, respectively. In addition, it is found that lower purity iron oxides exhibited a higher amplitude in the broader emission spectrum when compared to the iron oxides with high purity under the same experimental conditions. Therefore, by observing the amplitude of the broader emission spectra, it is possible to differentiate qualitatively between hematite and magnetite purities; moreover, from the average value of the FWHM of the spectral lines, it is possible to evaluate percentage purity content of hematite and magnetite, which are useful for different mechanical and biomedical applications. FTIR measurements also confirmed that the purity of the oxides can be found by measuring the peaks’ shifts. However, the proposed technique can be used in place of FTIR, where accessibility to the measurement’s location becomes problematic.

Highlights

Iron oxides are abundantly present in rocks, soils, and in all different partitions of the global system: atmosphere, pedosphere, biosphere, hydrosphere, and lithosphere.1 Iron oxides are used due to their abundance, low cost, low toxicity, excellent chemical stability, and tunable optical and magnetic properties in different areas such as steel and iron industries, catalytic reactions, paint manufacturing, biomedical applications, lithium-ion batteries, gas sensors, and magnetic storage devices.2–6For more than 100 years, people have appreciated the physical principles underlying infrared spectroscopy
The schematic of the experimental setup used for obtaining the emission spectra from the iron oxides pellets is depicted in Fig. 4 and is similar to the one used in other works of the authors;20,21 a Q-switch Nd:YAG laser with a maximum pulse repetition of 10 Hz, a pulse linewidth of 5 ns, and a beam diameter of ∼0.3 cm is used to heat up the pellet in order to generate the emission spectrum
There is a broad emission from the salt (∼2000 counts) that is extended along the region of interest covering the emission of the hematite and magnetite

Summary

Introduction

Iron oxides are abundantly present in rocks, soils, and in all different partitions of the global system: atmosphere, pedosphere, biosphere, hydrosphere, and lithosphere.1 Iron oxides are used due to their abundance, low cost, low toxicity, excellent chemical stability, and tunable optical and magnetic properties in different areas such as steel and iron industries (i.e., manufacturing of pure iron, steel, and many alloys), catalytic reactions, paint manufacturing, biomedical applications, lithium-ion batteries, gas sensors, and magnetic storage devices.2–6For more than 100 years, people have appreciated the physical principles underlying infrared spectroscopy. We propose using emission spectra to investigate the purity of hematite (α-Fe2O3) and magnetite (Fe3O4).

Results

Conclusion