Optical far infrared properties of FeS 2 (original) (raw)
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Optical Reflectivity Spectrum of a CuFeS2 Single Crystal
J Phys Soc Jpn, 1980
Optical reflectivity spectra have been measured at room temperature on a single crystal of CuFeS2 between 0.025 and 6 eV. The experimental results have been used to calculate the optical constants, the dielectric constant and the absorption coefficient. There have been found an absorption band with peaks at 1.0 and 2.1 eV and an absorption edge at approximately 3.2 eV. The band can be assigned to the charge-transfer transition from the valence band to the empty 3d states of Fe, and the edge can be attributed to the commencement of the band to band transition. A schematical energy level diagram for CuFeS2 is given from the result.
ELECTRONIC STRUCTURES OF FeS AND FeS2: X-RAY ABSORPTION SPECTROSCOPY AND BAND STRUCTURE CALCULATIONS
Journal of Physics and Chemistry of Solids, 1997
The bandstructures ofFeSandFeS2including theS3sand3pandtheFe 3d and4sstatesare calculated in thetight-binding approach. In thecaseofFeS,magnetic orderingistakenintoaccount. The FeK,FeL2,3, andSKX-rayabsorption edgeshavebeenrecorded andarediscussed intermsofthecalculated bandstructures. Thethreeabsorption edgesandthecorresponding partialdensityofstates(PDOS) in the conductionbandare presentedon a commonrelativeenergyscalefor bothcompounds. Thisallowsan interpretation ofthosestructures inthespectrawhichcorrespond to bandsnotaccessible bythecalculation (particularlythosederivedfrom Fe 4p states).It is shownthat the methodof usingband structure calculations togetherwitha maximumnumberof absorptionedgesof a compoundallowsto describe conductionbandsup to higherelectroniclevelsand givesa detailedinterpretation of X-rayabsorption spectra.
Journal of applied sciences and nanotechnology, 2022
In this work, the physical properties of iron sulfide (FeS2) thin films deposited by the chemical spray-pyrolysis (CSP) technique were studied. The thin films are deposited on glass substrates at 200 o C, using FeCl3 salt with thiourea (NH2)2CS as precursors. Structural analysis of X-Ray diffraction manifested that the thin films contain two phases: Marcasite and Pyrite in planes (110), (111) at angles 2θ =26.3°, 2θ =28.3° respectively. Optical properties analysis showed that the prepared iron sulfide thin-films were highly absorbing in the UV-Visible range and the absorption coefficient was in the range of 1.6x10 5 cm-1 with a relatively low resistivity of about 0.49 (Ω.cm). The calculated activation energy (Ea) was 0.024 eV and the bandgap value was 2.45 eV. Moreover, the FeS2 thin films were also deposited on (CdO) to fabricate a heterojunction photocell. In conclusion, there is the feasibility of preparing low-cost and highly absorbing iron sulfide (FeS2) thin films for optoelectronic applications with acceptable homogeneity using the spray-pyrolysis technique.
Study of Structural and Optical Properties of FeS2 Nanoparticles Prepared by Polyol Method
Journal of Nano- and Electronic Physics, 2020
FeS2 nanoparticles were prepared using a simple and cost-effective Polyol method with ethylene glycol and precursor thiourea as capping reagents. The crystalline structure of FeS2 nanoparticles were confirmed by X-ray diffraction. Dimensions of the unit cell and Pa-3 space group were determined by Rietveld refinement. The average crystallite size was found to be ~ 42.1 nm. The stoichiometry of these nanoparticles were also confirmed by, Raman and Fourier Transform Infrared Spectroscopy. Further, Raman spectroscopy revealed the chemical bonding and symmetry of molecules. FTIR spectroscopy exhibited the presence of functional groups of Fe=S, Fe-S and S-S in the samples. Advanced measurements and analysis towards the applicability of surfactant coated pyrite FeS2 nanoparticles for solar cell etc. applications are in progress.
Infrared studies of the surface of α-Fe2O3
Materials Chemistry and Physics, 1985
The surface chemistry and structure of a-Fe 0 23 obtained by thermal decomposition of a-FeOOH have been studied by IR spectroscopy. The spectra arising from the adsorption of some probe molecules (water, pyridine, ammonia, carbon monoxide, methanol) on samples after different pretreatments are analyzed, and the nature and behaviour of surface hydroxy groups, Lewis acid sites, acid-base couples and n-bonding adsorption sites are discussed. The results are interpreted on the basis of a disordered model of the {OOOll crystal face that is predominantly exposed on such samples. 0 Elsevier Sequoia/Pr~nted in The Netherlands
The Journal of Physical Chemistry C
Sulfur dimer (S22–) terminated pyrite FeS2{100} surfaces with a low energy electron diffraction (LEED) pattern of 2 × 1 symmetry are reported. The 2 × 1 symmetry correlates with the orientation of the anisotropic surface structure and external symmetry of macroscopic striations on the pyrite cube face. The basic condition to form these surfaces is a mild 200 V Ne+ sputter-cleaning procedure followed by a 570 K anneal of the sample in a 10–7 Torr S2(g) atmosphere. Controlled amounts of surface sulfur monomers (S2–) can be introduced by mild sputtering of the sulfur dimer terminated surfaces. At low monomer concentrations the surface displays the same characteristic 1 × 1 LEED pattern as that for fracture-generated surfaces. With increasing sulfur depletion, a (1/√2 × 1/√2)R45° LEED pattern emerges, and soft X-ray photoelectron spectroscopy (XPS) results show a sulfur dimer deficient near-surface region and a new high binding energy sulfur spectral component suggesting the presence of...
Observation of a Strong Infrared Magneto-Optical Effect in a Pyrite Type Ferromagnet CoS2
J Phys Soc Jpn, 1982
Reflectance magneto-circular dichroism spectra and Kerr rotation spectra have been measured for the first time on a pyrite type ferromagnet CoS2, for photon energies between 0.5 and 3.5 eV below the Curie temperature. There have been observed three major structures around 0.8, 1.5 and 2.8 eV, among which the most prominent is the one at 0.8 eV; the Kerr rotation reaches the value of 1.1° at the peak. Real and imaginary parts of the off-diagonal element of the dielectric tensor have been calculated from the observed spectra. Theoretical study has revealed that the line shape of the 0.8 eV structure can be explained in terms of the localized many-electron excitation associated with the d\varepsilon-dγ absorption edge of this compound. This corresponds to the narrow-band nature of the pyrite type compound.
Synthesis and structural characterization of FeS2 nanoparticles using rietveld refinement
AIP Conference Proceedings, 2019
We report the synthesis and characterization of FeS 2 nanoparticles (NPs) in view of their possible applications, which may range from organic and inorganic based hybrid solar cells to the replacements of Lithium Batteries (LIBs). The Polyol method was used to prepare the Iron Pyrite (FeS 2) NPs with reducing reagent Ethylene Glycol (EG) and precursor Thiourea. The crystalline quality and stoichiometry of synthesized FeS 2 NPs were confirmed by X-ray diffraction (XRD) and Raman Spectroscopy, which gave an average crystallite size of 35.4 nm. The Rietveld refinement of the diffraction data revealed the lattice parameters, hkl values, phase, Rp (Profile Factor) etc. of FeS 2 NPs through the profile matching routine of FullProf software. The elemental has been investigation has been performed using Energy-Dispersive X-ray Spectroscopy (EDS), where characteristic emission peaks of Fe and S elements were observed. Further, Raman Spectroscopy experiment provided information on chemical bonding and symmetry of molecules for the device possibilities of surfactant coated FeS 2 NPs.