The Effect of Carbon Defects in the Coal–Pyrite Vacancy on the Electronic Structure and Optical Properties: A DFT + U Study

Pyrite is a mineral often associated with coal in coal seams and is a major source of sulfur in coal. Coal–pyrite is widely distributed, easily available, low-cost, and non-toxic, and has high light absorption coefficient. So, it shows potential for various applications. In this paper, the density-functional theory (DFT + U) is used to construct coal–pyrite with carbon doped in the sulfur and iron vacancies of pyrite. The effects of different carbon defects, different carbon doping concentrations, and different doping distributions in the same concentration on the electronic structure and optical properties of coal–pyrite were studied. The results show that the absorption coefficient and reflectivity of coal–pyrite, when its carbon atom substitutes the iron and sulfur atoms in the sulfur and iron vacancies, are significantly higher than those of the perfect pyrite, indicating that coal–pyrite has potential for application in the field of photovoltaic materials. When carbon is doped in the sulfur vacancy, this impurity state reduces the width of the forbidden band; with the increase in the doping concentration, the width of the forbidden band decreases and the visible-light absorption coefficient increases. The distribution of carbon impurities impacts the band gap but has almost no effect on the light absorption coefficient, complex dielectric function, and reflectivity, indicating that the application of coal–pyrite to photovoltaic materials should mainly consider the carbon doping concentration instead of the distribution of carbon impurities. The research results provide a theoretical reference for the application of coal–pyrite in the field of photoelectric materials.

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The optical properties and in-situ observational evidence for the formation of brown carbon in cloud

10.5194/acp-2021-945 ◽

2021 ◽

Author(s):

Ziyong Guo ◽

Yuxiang Yang ◽

Xiaodong Hu ◽

Xiaocong Peng ◽

Yuzhen Fu ◽

...

Keyword(s):

Optical Properties ◽

Absorption Coefficient ◽

Light Absorption ◽

Cloud Water ◽

Water Soluble ◽

Substantial Contribution ◽

Supporting Evidence ◽

Brown Carbon ◽

Light Absorption Coefficient ◽

Free Particles

Abstract. Atmospheric brown carbon (BrC) makes a substantial contribution to aerosol light-absorbing and thus the global radiative forcing. Although BrC may change the lifetime of the cloud and ultimately affect precipitation, little is known regarding the optical properties and formation of BrC in the cloud. In the present study, the light-absorption properties of cloud droplet residual (cloud RES) were measured by coupled a ground-based counterflow virtual impactor (GCVI) and an Aethalometer (AE-33), in addition to the cloud interstitial (cloud INT) and ambient (cloud-free) particles by PM2.5 inlet-AE-33, at Mt. Tianjing (1690 m a.s.l.), a remote mountain site in southern China, from November to December 2020. Meanwhile, the light-absorption and fluorescence properties of water-soluble organic carbon (WSOC) in the collected cloud water and PM2.5 samples were also obtained, associated with the concentration of water-soluble ions. The mean light-absorption coefficient (Abs370) of the cloud RES, cloud INT, and cloud-free particles were 0.25 ± 0.15, 1.16 ± 1.14, and 1.47 ± 1.23 Mm−1, respectively. The Abs365 of WSOC was 0.11 ± 0.08 Mm−1 in cloud water and 0.40 ± 0.31 Mm−1 in PM2.5, and the corresponding mass absorption efficiency (MAE365) was 0.17 ± 0.07 and 0.31 ± 0.21 m2·g−1, respectively. A comparison of the light-absorption coefficient between BrC in the cloud RES/cloud INT and WSOC in cloud water/PM2.5 indicates a considerable contribution (48–75 %) of water-insoluble BrC to total BrC light-absorption. Secondary BrC estimated by minimum R squared (MRS) method dominated the total BrC in cloud RES (67–85 %), rather than in the cloud-free (11–16 %) and cloud INT (9–23 %) particles. It may indicate the formation of secondary BrC during cloud processing. Supporting evidence includes the enhanced WSOC and dominant contribution of secondary formation/biomass burning factor (> 80 %) to Abs365 in cloud water provided by Positive Matrix Factorization (PMF) analysis. In addition, we showed that the light-absorption of BrC in cloud water was closely related to humic-like substances and tyrosine/proteins-like substances (r > 0.63, p < 0.01), whereas only humic-like substances for PM2.5, as identified by excitation-emission matrix fluorescence spectroscopy.

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Crystal Structure and Photoelectric Property of Thin-Film Solar Cell Materials Cd1-xZnxS

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.512-515.23 ◽

2012 ◽

Vol 512-515 ◽

pp. 23-29

Author(s):

Fu Cheng Wan ◽

Wen Jiang Lu ◽

Fu Ling Tang ◽

Yu Dong Feng ◽

Zhi Min Wang ◽

...

Keyword(s):

Crystal Structure ◽

Optical Properties ◽

Electrical Properties ◽

Absorption Coefficient ◽

Band Gap ◽

Density Functional ◽

Doping Concentration ◽

Optical Absorption Coefficient ◽

Generalized Gradient ◽

Rate Of Increase

Based on density functional theory (DFT) within the framework of the generalized gradient approximation method, we have studied the Cd1-xZnxS sphalerite crystal structure and optical properties. We calculated electronic and optical properties of Cd1-xZnxS at the doping concentration x = 0, 0.25, 0.50, 0.75, 1.0. Optical properties (reflectivity, absorption coefficient, refractive index, dielectric function) and the electrical properties (band structure, electron density, etc.) are obtained including Zn-doing effects on the crystal structure, optical properties and electrical properties. With the increase of doping concentration x, the lattice parameter reduces from 0.5910 nm to 0.5409 nm; as a direct wide band gap semiconductor, its band gap increased from 1.15 to 2.22. Optical absorption coefficient increases with the increase of doping concentration, but the rate of increase is relatively small.

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Spectral bio-optical properties of water of Atlantic sector of Antarctic

Marine Biological Journal ◽

10.21072/mbj.2020.05.4.06 ◽

2020 ◽

Vol 5 (4) ◽

pp. 69-78

Author(s):

N. A. Moiseeva ◽

T. Ya. Churilova ◽

T. V. Efimova ◽

V. A. Artemiev ◽

E. Yu. Skorokhod

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter ◽

Absorption Coefficient ◽

Chlorophyll A ◽

Light Absorption ◽

Colored Dissolved Organic Matter ◽

Atlantic Sector ◽

Light Absorption Coefficient ◽

The Relationship

Studies of variability of spectral bio-optical properties of water of Atlantic sector of Antarctic were carried out during the 79th cruise of the RV “Akademik Mstislav Keldysh” (11.01.2020–04.02.2020). Chlorophyll a and phaeopigment concentration varied in the layer studied from 0.1 to 1.8 mg·m−3, except for two stations with content reaching 2.2 and 4.4 mg·m−3. The relationship was revealed between light absorption coefficient by phytoplankton and chlorophyll a concentration at a wavelength, corresponding to spectrum maxima: aph(438) = 0.044 × Ca1.2, r2 = 0.84 (n = 117); aph(678) = 0.021 × Ca1.1, r2 = 0.89 (n = 117). Spectral distribution of light absorption coefficient by non-algal particles and colored dissolved organic matter was described by exponential function. Absorption parameterization coefficients were retrieved: (1) light absorption coefficient by non-algal particles (0.001–0.027 m−1) and by colored dissolved organic matter (0.016–0.19 m−1) at a wavelength of 438 nm; (2) spectral slope coefficients of these components (0.005–0.016 and 0.009–0.022 nm−1, respectively).

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Effect of Varying Pnictogen Elements (Pn=N, P, As, Sb, Bi) on the Optoelectronic Properties of SrZn2Pn2

Zeitschrift für Naturforschung A ◽

10.1515/zna-2017-0388 ◽

2018 ◽

Vol 73 (4) ◽

pp. 285-293 ◽

Cited By ~ 1

Author(s):

G. Murtaza ◽

N. Yousaf ◽

A. Laref ◽

M. Yaseen

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Electronic Structure ◽

Absorption Coefficient ◽

Density Functional ◽

State Of The Art ◽

Photonic Devices ◽

Functional Theory ◽

Band Structure Calculations ◽

Structure Calculations

AbstractPnictogen-based Zintl compounds have fascinating properties. Nowadays these compounds have gained exceptional interest in thermoelectric and optoelectronic fields. Therefore, in this work the structural, electronic and optical properties of SrZn2Pn2 (Pn=N, P, As, Sb, Bi) compounds were studied using state-of-the-art density functional theory. The optimised lattice parameters (ɑ, c, c/ɑ and bond lengths) are consistent with the experimental results. The bulk moduli and c/a showed a decrease when changing the Pnictogen (Pn) anion from N to Bi in SrZn2Pn2 (Pn=N, P, As, Sb, Bi). The modified Becke-Johnson potential is used for band structure calculations. All compounds show semiconducting behaviour except SrZn2Bi2, which is metallic. Pn-p, Zn-d and Sr-d play an important role in defining the electronic structure of the compounds. The optical conductivity and absorption coefficient strength are high in visible and ultraviolet regions. These band structures and optical properties clearly show that SrZn2Pn2 compounds are potential candidates in the fields of optoelectronic and photonic devices.

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Reciprocating internal combustion compression-ignition engines. Apparatus for measurement of the opacity and for determination of the light absorption coefficient of exhaust gas

10.3403/01927221u ◽

2015 ◽

Keyword(s):

Absorption Coefficient ◽

Light Absorption ◽

Internal Combustion ◽

Exhaust Gas ◽

Compression Ignition ◽

Compression Ignition Engines ◽

Light Absorption Coefficient

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Particulate light absorption and the prediction of phytoplankton biomass and planktonic metabolism in northeastern Spanish aquatic ecosystems

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-184 ◽

2000 ◽

Vol 57 (1) ◽

pp. 25-33 ◽

Cited By ~ 2

Author(s):

C M Duarte ◽

S Agustí ◽

J Kalff

Keyword(s):

Absorption Coefficient ◽

Light Absorption ◽

Aquatic Ecosystems ◽

Coastal Lagoons ◽

Strong Relationship ◽

Community Respiration ◽

Chl A ◽

Light Absorption Coefficient ◽

Alpine Rivers ◽

Detrital Particles

Examination of particulate light absorption and microplankton metabolism in 36 northeastern Spanish aquatic ecosystems, ranging from alpine rivers to inland saline lakes and the open Mediterranean Sea, revealed the existence of general relationships between particulate light absorption and the biomass of phytoplankton and microplankton metabolism. The particulate absorption spectra reflected a dominance of nonphotosynthetic, likely detrital, particles in rivers and a dominance of phytoplankton in coastal lagoons. There was a strong relationship between the light absorbed by phytoplankton and the chlorophyll a (Chl a) concentration of the systems, which indicated an average (±SE) Chl a specific absorption coefficient of 0.0233 ± 0.0020 m2·mg Chl a-1 for these widely diverse systems. Chl a concentration was a weaker predictor of the total particulate light absorption coefficient, pointing to an important role of nonphytoplanktonic particles in light absorption. Gross production was very closely related to the light absorption coefficient of phytoplankton, whereas community respiration was strongly correlated with the total particulate light absorption coefficient, indicating the optical signatures of sestonic particles to be reliable predictors of planktonic biomass and metabolism in aquatic ecosystems.

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Electronic Structure and Optical Properties of Non-Metals (N, F, P, Cl, S)-Doped Cubic NaTaO3 by Density Functional Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1245 ◽

2009 ◽

Vol 79-82 ◽

pp. 1245-1248 ◽

Cited By ~ 12

Author(s):

Pei Lin Han ◽

Xiao Jing Wang ◽

Yan Hong Zhao ◽

Chang He Tang

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Electronic Structure ◽

Visible Light ◽

Absorption Edge ◽

Density Functional ◽

Red Shift ◽

Functional Theory ◽

Photoactive Materials ◽

Metal Doped

Electronic structure and optical properties of non-metals (N, S, F, P, Cl) -doped cubic NaTaO3 were investigated systematically by density functional theory (DFT). The results showed that the substitution of (N, S, P, Cl) for O in NaTaO3 was effective in narrowing the band-gap relative to the F-doped NaTaO3. The larger red shift of the absorption edge and the higher visible light absorption at about 520 nm were found for the (N and P)-doped NaTaO3. The excitation from the impurity states to the conduction band may account for the red shift of the absorption edge in an electron-deficiency non-metal doped NaTaO3. The obvious absorption in the visible light region for (N and P)-doped NaTaO3 provides an important guidance for the design and preparation of the visible light photoactive materials.

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Oxygen vacancy and doping atom effect on electronic structure and optical properties of Cd2SnO4

RSC Advances ◽

10.1039/c7ra10641f ◽

2018 ◽

Vol 8 (2) ◽

pp. 640-646 ◽

Cited By ~ 8

Author(s):

Mei Tang ◽

JiaXiang Shang ◽

Yue Zhang

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Oxygen Vacancy ◽

Density Functional ◽

Generalized Gradient ◽

Functional Theory ◽

The Density Functional Theory ◽

La Doped ◽

Doping Atom ◽

Atom Effect

The electronic structure and optical properties of oxygen vacancy and La-doped Cd2SnO4 were calculated using the plane-wave-based pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA).

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