Optical Properties Of Pristine Research Articles

Effect of gamma rays on magnetic and linear/nonlinear optical properties of pristine and modified nickel ferrite nanoparticles

Effect of gamma rays on magnetic and linear/nonlinear optical properties of pristine and modified nickel ferrite nanoparticles

Exploring the structural, morphological, optical and magnetic properties of pure and Ni-doped Triple Perovskite La2SrFe2TiO9 for magneto-opto electronic applications

The Present work represents the Structural, morphological, magnetic, and optical properties of Pristine and Ni-doped La2SrFe2TiO9 Triple Perovskite. The samples were synthesized by using the solid-state reaction approach. We have carried out the structural characterization of the La2SrFe2-xNixTiO9 (x = 0.0, 0.1, 0.2, 0.3 and 0.5) Triple Perovskite by using X-ray diffraction and found that all the synthesized samples were grown in a single phase with space group (Pnma) which has been confirmed further by Rietveld Refinement. The microstructural analysis and the elemental composition analysis were carried out using a Field Emission Scanning Electron Microscope (FE-SEM) and Energy dispersive spectroscopy (EDS) respectively. The morphological studies of the sample reveal that the grain size of the sample decreases (1.11–0.75 μm) with Ni Doping. The optical band gap of the samples was characterized by UV–vis spectroscopy measurements, and we have obtained the value of the energy band gap from 2.02 to 1.67 eV, confirming the application of the material in the Infrared region of the electromagnetic spectrum. The M − H measurements reveal the stabilized ferromagnetic character of the pure La2SrFe2TiO9 Triple Perovskite upon Ni doping. The XPS Studies confirm that Ni exists in the form of Ni2+ while Fe exists in the form of Fe3+. The magnetic measurements were understood theoretically by using the mathematical equation. The current study indicates the stability of the samples, and their possible utilisation in spintronics, magnetic storage devices, magneto-optoelectronics, and solar cell applications.

Research on electronic and optical properties of pristine and Ag/Au/Cu-doped graphene/MoS2 heterostructures

The Dirac cone in the single-layer graphene limits its application in electronic devices such as Schottky barrier diodes and field-effect transistors. Thus, we make the novel heterostructures based on graphene to solve this problem. The electronic and optical properties of pristine and Ag/Au/Cu-doped graphene/MoS2 heterostructures are investigated by using the density functional theory. For the Ag/Au/Cu-doped MoS2 monolayer, the results show that they are magnetic. Their bands across the Fermi level, which indicates these systems are metallic. For the Ag/Au/Cu-doped graphene/MoS2 heterostructures, they are metallic and nonmagnetic. Especially in the Au-doped graphene/MoS2, the Dirac cone opens about 66 meV. It means that Au-doped graphene/MoS2 has the potential to be a candidate material for high speed electronic devices. Compared with pristine heterostructure, the probability of electron transition in the low energy region is the enhanced in Ag/Au/Cu-doped systems. The optical absorption coefficient of doped heterostructure is enhanced in the range of 0–0.4 eV and 1.7–2.7 eV. This work indicates that these heterostructures have a certain potential in the application of nanodevices.

Engineering the electronic, magnetic, and optical properties of GaP monolayer by substitutional doping: a first-principles study

In this paper we present a thorough first-principles density functional theory based computational study of the structural stability, electronic, magnetic, and optical properties of pristine and doped gallium phosphide (GaP) monolayers. The pristine GaP monolayer is found to have a periodically buckled structure, with an indirect band gap of 2.15 eV. The doping by X (B, Al, In, C, Si, Ge, Sn, Zn, and Cd) at the Ga site, and Y (N, As, Sb, O, S, Se, Te, Zn, and Cd) at the P site is considered, and an indirect to direct band gap transition is observed after doping by In at the Ga site. For several cases, significant changes in the band gap are seen after doping, while the system becomes metallic when O is substituted at the P site. The spin-polarized band structures are calculated for the monolayers with doping-induced magnetism, and we find that for some cases a direct band gap appears for one of the spin orientations. For such cases, we investigate the intriguing possibility of spin-dependent optical properties. Furthermore, for several cases the band gap is very small for one of the spin orientations, suggesting the possibility of engineering half metallicity by doping. For the layers with direct band gaps, the calculated optical absorption spectra are found to span a wide energy range in the visible and ultraviolet regions. The computed formation energies of both the pristine and doped structures are quite small, indicating that the laboratory realization of such structures is quite feasible. On the whole, our results suggest that the doped GaP monolayer is a material with potentially a wide range of applications in nanoelectronics, spintronics, optoelectronics, solar cells, etc.

Electronic and optical properties of pristine and alkali metal atom-adsorbed QPHT-graphene: first-principles calculations

Electronic and optical properties of pristine and alkali metal atom-adsorbed QPHT-graphene: first-principles calculations

Stability, electronic, optical and thermoelectric properties of site-substituted [formula omitted]

To unravel the structural and chemical stability, electronic, transport, and optical properties of pristine and site substituted lanthanum vanadate, LaVO3, we employed the density functional theory (DFT) and the dynamical mean field theory (DMFT). The generalized gradient approximation (GGA) and the DMFT with continuous time quantum Monte Carlo (CT-QMC) approach is used for the impurity solver. The variation of the spectral density are studied with different values of the onsite Coulomb interaction (U) and exchange interaction (J), as well as the thermodynamic parameter (β), to investigate the metal insulator transition (MIT) for these materials, which are useful for designing Mottronics, neuromorphic computing devices. The predicted values of U and β for the Mott–Hubbard MIT in La0.40Ca0.60V O3 are consistent with current experimental data. The studied sample’s a characteristic sharp quasi-particle peak is found to be at U = 5 eV and β = 6 (eV)−1. The Mott quantum critical point (QCP) is also computed for an elevated temperatures and it is found at U = 2.95 eV and β = 23.58 (eV)−1. With U = 5.0 eV, β = 10.0 (eV)−1, the clear Mott gaps for La0.40Ca0.60V O3 and La0.60Ca0.40V O3 are estimated as 0.74 eV and 1.64 eV, respectively. The electrical and thermal conductivities are calculated at room temperature using the BoltzTraP code, and they are found to be 2.11 (Ωms)−1 and 1.51 W/(mKs), respectively, for a given chemical potential μ = −0.14 eV of the system. The figure of merit (ZT) is estimated to be 1.78 at μ = −1.44 eV. Larger values of the Seebeck coefficient (S), ZT, and thermoelectric power factor (TPF) indicate that La0.40Ca0.60V O3 system is a good candidate of thermoelectric material. The calculated frequency dependent optical conductivity (Drude weight) on the dependency of U and β for the metal insulator transition supports the other calculations.

Mechanical, structural and optical properties of pristine and PVA capped zinc oxide nanocomposites

Zinc oxide (ZnO) and Poly vinyl alcohol capped zinc oxide (PVA-ZnO) of different concentrations were synthesized by precipitation method. PVA capped ZnO nanoparticles were examined to study the influence of ZnO nanoparticles on PVA as it possesses various properties such as mechanical, structural and optical. The synthesized nanoparticles were analyzed using XRD, FTIR, UV-Vis, SEM EDAX techniques. In the FTIR spectrum, the peak observed at 559 cm−1 indicates M–O stretching in the samples which specifies the interaction of ZnO with PVA matrix. The XRD patterns confirmed the presence of ZnO nanoparticles and the size of the ZnO nanoparticles and PVA- ZnO NPs were 76 nm and 61 nm. The uniform dispersion of ZnO nanoparticles as well as the interaction of nanoparticles with the PVA matrix were also observed in SEM analysis and the purity of NPs was determined from EDS analysis. The UV-vis spectra show the light absorption behavior of the ZnO NPs and ZnO-PVA nanocomposites and they exhibited high absorption in the UV region. The mechanical properties such as tensile strength and elongation were also analyzed for the synthesized samples.

First-principles DFT study of structural, electronic and optical properties of Cu-doped TiO[formula omitted] (112) surface for enhanced visible-light photocatalysis

In this work, first-principles density functional theory (DFT) calculations are used to study the structural, electronic, and optical properties of pristine and Cu-doped TiO2 (112) surface in oxygen-rich environment, and then compare the results to the bulk phase. We find the pristine (112) surface to be chemically and thermodynamically stable, exhibiting indirect band gap value of 2.89 eV. By 5.6% concentration of Cu-doping, the energy gap in the asymmetric spin bands and PDOS reaches a value of 2.00 eV, with induced magnetism. The visible range direct band gap in Cu-doped systems enhances the photo-absorption triggering the threshold value and the inter-band transitions by lowering the intensity of the dielectric constant, reflectance, and refractive index, making them suitable candidates for optoelectronics and photocatalytic applications.

A first principle study to investigate structural, electronic and optical properties of pristine and valency comparable Co, P decorated graphene like boron nitride (BN) nanosheets

ABSTRACT In this ongoing research work, a density functional theory (DFT) study has been performed to investigate the structural, chemical, electrical, and optical properties of the boron nitride nanosheets (BNNSs) by replacing one boron atom from BNNSs with valency comparable Cobalt (Co) and Phosphorus (P) atoms. The order of the calculated cohesion energy is −5.96 > −5.82 > −5.81 eV, respectively, for BN, Co@BN and P@BN, which leads to good structural stability. The calculated Eg follows the order 6.82 > 5.84 > 3.82 eV respectively for BN, P@BN and Co@BN, which reveal evidence of enhancing the electrical properties of the doped structures. Vibrational spectroscopies, global descriptors-DFT parameters, DOS, MEP and absorption spectra gave details information about the enhancement of the various properties of the BN nanosheets by doping, and suggest a high range of application in technology.

Effect of Pt Decoration on the Optical Properties of Pristine and Defective MoS2: An Ab-Initio Study.

Using structural relaxation calculations and first-principles molecular dynamics (FPMD), we performed numerical simulations to explore the interaction of a 2D MoS2 surface and a platinum atom, calculating the optical properties of the resulting material. We explored three initial positions for the interaction of the Pt atom and the pristine MoS2 surface, plus another position between Pt and the MoS2 surface with a sulfur vacancy VS. The surface absorbed the Pt atom in all cases considered, with absorption energies ranging from −2.77 eV to −5.83 eV. We calculated the optical properties and band structure of the two cases with the largest absorption energies (−3.45 eV and −5.83 eV). The pristine MoS2 is a semiconductor with a gap of around 1.80 eV. With the adsorption of the Pt atom (the −3.45 eV case), the material reduces its band gap to 0.95 eV. Additionally, the optical absorption in the visible range is greatly increased. The energy band structure of the 2D MoS2 with a sulfur vacancy VS shows a band gap of 0.74 eV, with consequent changes in its optical properties. After the adsorption of Pt atoms in the VS vacancy, the material has a band gap of 1.06 eV. In this case, the optical absorption in the visible range increases by about eight times. The reflectivity in the infrared range gets roughly doubled for both situations of the Pt-absorbed atom considered. Finally, we performed two FPMD runs at 300 K to test the stability of the cases with the lowest and highest absorption energies observed, confirming the qualitative results obtained with the structural relaxations.

Large shift in surface plasmon resonance wavelength with growth of embedded Au nanoparticles in fullerene C60 by Collision Cascades

We report a 220 keV Ag ion beam irradiation-induced modifications of thin films of fullerene C60 containing gold (Au) nanoparticles. Nanocomposite thin films of Au-C60 were synthesized using a thermal co-deposition technique on a glass substrate. The as-deposited (pristine) thin films were irradiated by 220 keV Ag ion beam at different fluences ranging from 1 × 1013 ions/cm2 to 3 × 1016 ions/cm2 utilizing a low energy ion accelerator. The optical properties of pristine and irradiated thin films of Au-C60 were investigated using UV–visible spectroscopy. A redshift in the Surface Plasmon Resonance (SPR) wavelength from ~ 598–775 nm was obtained with increasing fluence up to 1 × 1014 ions/cm2, which indicated the growth of Au nanoparticles in the fullerene matrix due to ion irradiation. It was further confirmed by High-Resolution Transmission Electron Microscopy (HRTEM). With further increase in fluence, a blue shift from ~ 775–570 nm was obtained at a fluence of 1 × 1016 ions/cm2. The transformation of fullerene C60 into amorphous carbon (a:C) with increasing fluence of Ag ion beam was the main cause of this blue shift which was further confirmed by Raman spectroscopy. An increase in surface grain size with ion fluence was observed by Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM). The X-ray Photoelectron Spectroscopy (XPS) measurements were used for the chemical state analysis of the nanocomposite thin films before and after irradiation. The current-voltage measurements confirm the increase in the conductivity of the nanocomposite films with the fluence due to its transformation in carbon at higher fluences. The control on the size of Au nanoparticles and tuning of SPR wavelength by low energy ion irradiation may enhance the applicability of Au-C60 nanocomposite in organic solar cell.

Effects of transition metal doping on CsGeBr3 perovskite: First-principles study

Metal halide perovskites have shown the most promising results as the light-harvesting section of photovoltaics and opto-electronic devices. Among the non-toxic halide perovskites, CsGeBr3 was found to be the best candidate for opto-electronic applications; however, it is understood that the efficiency of CsGeBr3 can be further increased with the insertion of transition metals as dopants. In this article, the first-principles density functional theory calculations are used to predict the mechanical, structural, electronic, and optical properties of pristine, Ni-doped, Mn-doped, and Fe-doped CsGeBr3 with 12.5% of doping concentration. All the doped materials are found to be ferromagnetic and mechanically stable. They have finite magnetization values. The optical absorption edge in all the doped materials shows that they have additional peaks within the large emission range of solar radiation, which makes them more suitable than the pristine material for photovoltaics and opto-electronic applications. Among the doped materials, Mn-doped and Fe-doped CsGeBr3 have comparably higher absorption peaks and are almost identical in shape. The electronic bandgap is smaller than the pristine structure in the case of Fe-doped CsGeBr3 and larger for Ni and Mn-doped CsGeBr3. These combinational analyses lead to the decision that, among the non-toxic, inorganic perovskite materials, Fe-doped CsGeBr3 is better suited for the use in opto-electronic applications.

Effect of annealing on the structural and optical properties of pristine and cerium doped calcium tungstate nanoparticles synthesized via hydrothermal method

The work is an investigation of the effect of annealing temperature on pristine and rare earth doped CaWO4 nanoparticles with hydrothermal route. The sample was annealed at two varied temperatures 800 ºC and 1200 ºC for 5 h. The structural analysis reveals the reduction in the broadening of the peaks as a result of annealing. Surface morphology shows the formation of agglomerated structures. In Ce3+:CaWO4 nanoparticles the morphology is modified to dumbbell like and flake like structures after annealing. Raman shift observed at 909 cm−1 Ag modes confirms the presence of CaWO4 nanoparticles with its own rotational and vibrationalmodes. Increase in the absorption peak intensity and a double absorption edge appears as an intermediate energy level state after the inclusion of Ce3+ ion as dopant.

A Frist Principle Study to Investigate Structural, Electronic and Optical Properties of Pristine and Valency Comparable Co, P Decorated Graphene Like Boron Nitride (Bn) Nanosheets

A Frist Principle Study to Investigate Structural, Electronic and Optical Properties of Pristine and Valency Comparable Co, P Decorated Graphene Like Boron Nitride (Bn) Nanosheets

Influence of Defects on Optical and Nonlinear Optical Properties of Pristine and Nickel Doped Zinc Oxide Nanostructures

Influence of Defects on Optical and Nonlinear Optical Properties of Pristine and Nickel Doped Zinc Oxide Nanostructures

First-principles study of the electronic and optical properties of homo-doped 2D-hBN monolayer

The two-dimensional (2D) hexagonal boron nitride (h-BN) semiconductor has a wide bandgap and is made up of boron (B) and nitrogen (N) atoms arranged in a honeycomb lattice and connected by strong covalent bonds. We use first-principles based density functional theory (DFT), hybrid functional (GauPBE), and random phase approximation to explore the electronic and optical properties of pristine and 2D-(h-BN)1-xCx, x = 11 % and 22 % (carbon homo-doped 2D h-BN) monolayers. The formation energy analysis showed that the structural stability of carbon homo-doped 2D h-BN monolayer was better than 2D-(h-BN)1-xSx, x = 11 % and 22 % (sulfur homo-doped 2D h-BN) monolayer. The estimated band gaps in the carbon homo-doped 2D h-BN system were 5.9 (pristine), 4.25 (x = 11 % C), and 2.42 (x = 0.22 % C) eV, with the band gap decreasing as the concentration of the C atom increased. The polarization was parallel to the sheet as the carbon-homo doping concentration increased, and the band edge dropped to a minimal energy level, as validated by DFT + RPA calculations. Furthermore, the presence of LFE influence the optical properties of the homo-doped 2D h-BN.

Insight into Structural and Optical Properties of Pristine and Sr2+ Doped La2NiMnO6

Double perovskites oxide (DPO) multiferroics La2-xSrxNiMnO6(x=0.0, 0.1, 0.2, 0.4, 0.6) are synthesized by sol-gel technique. The structural, optical and electrical (both DC and AC) properties of La2-xSrxNiMnO6 have been investigated by XRD and FTIR spectroscopy and two-probe resistivity and dielectric measurements as a function of temperature, respectively. The effect of doping of Strontium at A-site in double perovskites is discussed. XRD has revealed the formation of monoclinic structure of La2-xSrxNiMnO6 with space group P21 / n for x=0.0 and P21 for x=0.1, 0.2, 0.4, 0.6. The average crystallite size has been calculated to be in the range 31 to 46 nm as determined by Debye Scherrer equation. Infrared active optical phonons observed from reflectivity spectra have been analysed fitting the theoretical oscillators using Lorentz oscillator model. We have observed several well-resolved phonon modes in La2-xSrxNiMnO6 with increasing dopant concentration. Activation energy calculated using Arrhenius Plot is in the range of 0.31 to 0.18 eV, confirming the semiconducting nature of all samples. The dielectric constant and tangent loss as a function of temperature and frequency are also discussed for these multiferroics.

Femtosecond relaxation dynamics of two‐dimensional BiOI nanoplatelets as efficient photocatalysts

AbstractThe structural and optical properties of pristine and photoactivated surfaces of facet [001] of 2D BiOI nanoplatelet powders synthesized with an antisolvent method were studied using X‐ray diffraction (XRD), a scanning electron microscope, X‐ray photoelectron spectra (XPS), visible–near infrared (vis–NIR) absorption, and transient absorption spectroscopic techniques. The synthesized BiOI nanoplatelets possessed a tetragonal structure with length 200–400 nm and thickness less than 50 nm. XRD analysis showed that the photoactivation did not affect the crystal structure. In contrast, the XPS analysis showed vacancies associated with elements Bi, I, and O. The band gaps estimated from the diffuse reflectance spectra of pristine and photoactivated samples are 1.83 and 1.80 eV, respectively. Femtosecond transient‐absorption spectra measured in the vis–NIR (2.25–0.9 eV) region showed photobleach bands associated with the band edge, shallow trap, and deep trap states. A global fit of the transient spectral profiles showed that all bands decay synchronously for both pristine and photoactivated samples, but the photoactivated samples showed a greater magnitude of carrier‐carrier annihilation following photoexcitation due to photodoping caused by defects. A carrier‐relaxation model involving thermal equilibrium between band‐edge, shallow, and deep trap states is proposed to explain the synchronous decay of all bands.

Structural, electronic and optical properties of strontium and nickel co-doped BaTiO3: A DFT based study

Density functional theory-based investigation of the structural, electronic, and optical properties of pristine and strontium, nickel doped barium titanate has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The lattice constants of optimized structure, the electronic band structures, total and partial density of states and the optical properties such as absorption, reflectivity, dielectric function, photoconductivity, refractive index and the loss function of the pristine and doped materials have been calculated and thoroughly explained. In this study, we have found (Sr, Ni) co-doping in BTO reduces the lattice constant and structural volume. The band gap of co-doped material found less than the pristine BTO. The simulated optical spectroscopic analysis reveals that the (Sr, Ni) co-doped materials are good dielectric and photoconductive materials.

Electronic and optical properties of pristine and Li/Na/K/Mg/Ca decorated net-Y: First-principles calculations

In this manuscripts, first principles based on density functional theory are used to study the optical properties of pristine and alkali/alkaline-earth metal atoms decorated net-Y. Based on the data of reflection, absorption, refraction, complex dielectric function and loss function under three different polarization, the optical properties of pristine and decorated net-Y are studied for the first time. The results show that the alkali/alkaline-earth metal decorated net-Y exhibits a significant optical response in a wide frequency range of 0 eV–27.0 eV. Under Ex and Ey polarization, alkali metals and alkaline-earth metals can notably change the reflection, refraction, absorption, and energy loss of net-Y. Under Ez polarization, except that net-Y exhibits a certain optical response in the higher ultraviolet band, there is no obvious response in other frequency ranges, and the modification of alkali/alkaline-earth metals will not have a significant impact on the optical properties of net-Y. Meanwhile, under Ex and Ey polarization, with the increase of the modified atomic number, the static dielectric constant, the maximum reflection coefficient, the static refractive index and the maximum absorption coefficient all show different degrees of oscillation behavior, not monotonic changes. Under Ez polarization, the relative optical property coefficients do not change significantly. These results imply that the optical performance of net-Y can be effectively controlled by changing the type of modified alkali/alkaline-earth metals atoms.