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Along this research the (110), (101) (200) and (211) surfaces were chosen to be studied by considering their atomic surface density. The surfaces were studied using CASTEP for the transition state search by DFT calculations, the initial coordinates that establish the SnO2-Methane distance were obtained with Adsorption Locator, a software able to calculate adsorption configurations using Monte Carlo methods. The results show that in terms of overall energy change, surface (101) presents the most favorable configuration with an exothermic total-energy change (form CH4 on the surface to a CO and H2O molecules on the surface) of − 18.47 kcal/mol, being the worst case the CH4 on a (200) surface with an endothermic total energy-change of 128.86 kcal/mol. In terms of the TS energy, the (101) surface remains as the most favorable system with energy maximums on the TS reaction path of 99.25 kcal/mol for the dissociation and adsorption of the CH4 molecule on the surface, and a maximum of 266.42 kcal/mol for the desorption and formation of the CH4 and H2O molecules on the SnO2 surface.

Regarding advanced 5G mobile communication, microwave dielectric ceramics are considered as the most potential materials to develop new-generation base station resonators. Herein, ZnNb2O6 ceramics with er of approximately 24 have been prepared using the solid-state reaction method, with tailored extra ZnO of x mol% (x = 1, 2 and 3). We have for the first time applied the P-V-L chemical bond theory to investigate ZnNb2O6 ceramics with ZnO doping, by exploring the relationship of dielectric properties and chemical bond characteristics. Particularly, the Raman spectra demonstrates that the full width at half maximum of υ1 (Ag) vibration mode can exhibit significant correlation with the quality factor (Q × f ). To further support the experimental study, we have also conducted the first-principle calculation of electron density difference via CASTEP package, which further confirms the change of temperature coefficient of resonance frequency (τf ). Our newly designed ZnNb2O6 ceramics doped with 1 mol% ZnO exhibit excellent dielectric properties, i.e., er = 23.74, Q × f = 102,824 GHz and τf = −55.38 ppm/°C, which demonstrates great potential to construct miniaturized 5G base station with advanced ceramic dielectrics.

The structural, electronic, optical, and thermodynamic properties of the YRu2P2 superconductor are investigated theoretically using the CASTEP (Cambridge Serial Total Energy Package) code, which utilizes an ultra-soft pseudopotential USP plane wave and a Perdew Burke Ernzerhof (PBE) exchange–correlation functional of the Generalized Gradient Approximation (GGA). The evaluated value of the lattice parameters is found to be 4.84 A. The band structure of the compound indicates that this compound does not possess the band gap. The absence of the band gap suggests that the compound has a metallic nature. The density of states (partial and total) verifies the findings obtained from band structure. The existence of strong ionic contact between Ru–Ru atoms is shown by the negative value of the Mulliken population. The research has also been done on the optical properties of the material to find out how it responds optically. The results of the elastic constant calculation show that the material is mechanically stable and brittle in its natural state. The positive value of AU indicates that the compound is anisotropic. It is also revealed from the AG and AB values that the compound has anisotropic characteristics. Vickers hardness value obtained for the compound demonstrates that it is relatively hard in nature. Along with the initial elastic modulus calculation, the bulk, shear, and Young’s modulus are also determined. The existence of covalent character in the compound is shown by the Poisson’s ratio. The thermal conductivity, melting point, and Dulong-Petit limit of the material have all been determined to perform a more in-depth analysis of the material. The overlapping of the Fermi bands shows that the material is a superconductor, and the material’s metallic nature suggests that it will be an excellent reflector of incoming light.

Se sintetizaron nanovarillas de óxido de manganeso en fase cristalina beta (β-MnO2). Microscopía electrónica de barrido (SEM) y difracción de rayos-X (XRD) confirmaron la morfología y fase cristalina, respectivamente. Mediante la teoría del funcional de densidad (DFT), se calcularon las propiedades mecánicas teóricas de β-MnO2 con el programa CASTEP. Se realizó una optimización de la geometría de la celda unitaria, determinándose las constantes elásticas Cij, calculándose los valores del módulo de Young y de corte, y el coeficiente de Poisson, entre otros. Los resultados fueron comparados con los valores reportados en la literatura, encontrándose una significante similitud en los parámetros analizados. Las relaciones de Cij indicaron la aceptación de los criterios de Born, confirmando la estabilidad de la estructura cristalina de β-MnO2. La constante C44, así como el módulo de volumen y de corte, mostraron valores grandes, lo que indica un material con considerable dureza. Este comportamiento fue confirmado con el valor obtenido de la razón del módulo de volumen entre el módulo de corte por la aproximación de Hill. El entendimiento de las propiedades calculadas en este estudio usando CASTEP permitirá obtener parámetros adicionales de propiedades ópticas, termodinámicas, entre otras, así como el desarrollo de modelaciones y simulaciones que permitan entender y aplicar los conocimientos adquiridos a aplicaciones reales (experimentales), p. ej., en la remoción de contaminantes.

Sb-doped Y2O3, a compound with excellent optical properties, is used in laser applications. Recently, it has been found that it coexists in two distinct polymorphs upon doping with various levels of Sb. Therefore, the electronic structure and optical properties of Sb-doped Y2O3 corresponding to two distinct phases, i.e., bixbyite and fluorite, are explored in this paper using the CASTEP density functional theory (DFT) code. Sb is substituted at Y sites in pure Y2O3 in both phases, and the corresponding band structure, density of states, and various optical properties, namely the dielectric function, refractive index, reflectivity, and optical loss functions, are investigated. The results reveal that Sb-doped Y2O3 in fluorite phase is conductive for 12.5% doping but shows a small gap of 0.45 eV in the case of 25% Sb doping. Moreover, the fluorite phase of Sb-doped Y2O3 has defect states in the bandgap above the Fermi level, while the bixbyite phase exhibits insulating behavior. Moreover, the bandgap of the bixbyite phase steadily decreases with increasing Sb doping concentration. The results for the optical properties reveal that new kinds of excitation and plasmonic states emerge in Sb-doped bixbyite Y2O3 whereas no such transitions appear upon doping of the fluorite structure.

In this study, the electronic structures and magnetic and elastic properties of Cr2FeZ (Z = Sb, As) Heusler alloys were investigated through density functional theory calculations, which uses the generalized gradient approximation for the exchange-correlation functional included in the CASTEP software package. The results revealed that the Cr2FeSb and Cr2FeAs alloys successfully formed stable Hg2CuTi-type structures at finite temperatures. The ground-state properties of the stable structures were calculated, including lattice parameters, magnetic moments, and bulk moduli. The Cr2FeSb and Cr2FeAs alloys exhibited nearly half-metallic properties and high spin-polarization levels and thus can be used as half-metal/ferromagnetic metal (HM-FM) materials.

We studied the structural, elastic, electronic, dynamic and optical properties of scandium and yttrium nitrides in the zinc blend structure. The GGA, LDA and GGA-PBESOL approaches, as well as the HSE hybrid functional, were used in the representation of the electronic exchange and correlation effects. The lattice constant, the bulk modulus and its pressure derivative calculated in the HSE hybrid approach are predictions. The elastic constants and B/G ratio infer that ScN and YN are elastically stable and ductile in nature. ScN and YN in the zinc blend structure show an isotropic linear compressibility and anisotropic Young's modulus, shear modulus and Poisson's ratio. The anisotropy and hardness in ScN and YN compounds are more pronounced in the LDA approach. The X–X (W–W) direct band gap in scandium (yttrium) nitride translates its semiconductor character in the zinc blend structure. The N: p orbit and small contribution of Sc: d (Y: d) site are responsible to the optical modes, while Sc: d (Y: d) site and small contribution of N: p orbit are the sign of acoustical modes. The absorption peaks are assigned to photo transitions energies from maximum valence band to minimum conduction band.

Keto-bromothymol blue [BTB]keto was quantitatively prepared by potassium permanganate oxidation of bromothymol blue in an alkaline medium at pH > 12. When reacting with dinitrophenyl hydrazine and hydroxylamine, the obtained keto derivatives were characterized by FTIR, TDDFT-DFDT computations, and optical properties. The resulting compounds were found to have a high chelation affinity with most of the dinitrophenyl hydrazine and hydroxylamine forming stable bromothymol blue coordination compounds. The commodity has low cost and high performance and is used in food, drink, or other non-food applications such as pharmaceuticals. Furthermore, keto-bromothymol blue dye is applied for commercial, psychological, and functional purposes in dietary supplements and pharmaceutical products. The characterization of the [BTB]keto, [KBTB-DNPH], and [KBTB-HA] thin films was carried out by some practices comprising UV–Vis, and thin films were fabricated by a spin coating. The direct energies were 2.452 eV, 1.991 and 2.927 eV for [BTB]keto, [KBTB-DNPH] and [KBTB-HA] thin films, respectively. The $$\Delta {E}_{\mathrm{g}}^{\mathrm{Opt}}$$ values were computed depend on the difference among HOMO and LUMO using the DMol3 method in TDDFT-DFT computations. The optical dispersion of the thin films was confirmed in terms of WD model. DFT/DMol3 and Gaussian 09w/DFT computations were used for the optimization of the keto-derivatives as gaseous state molecule matrices. The Gaussian program is in good agreement with the experimental analysis for synthetic IR, MEP, and UV–Vis optical properties. In addition, the optoelectrical parameters have been calculated for the film, namely n(λ), k(λ), dielectric constant, and optical conductivity. CASTEP simulated values are consistent with the experimental values for optical parameters of dye derivative thin films. The fabricated thin films can be used as a candidate material for optoelectronic devices and solar cells.

Silicon purification with Al–Si solvent refining is a potential method to obtain solar grade silicon (SoG-Si). Hydrogen is a helpful element to enhance the removal of impurity boron during the Al–Si solvent refining. However, the interaction mechanism between hydrogen and boron is not very clear. In this paper, the ab initio calculation method, which is based on the density functional theory (DFT), was adopted to further understand the interaction behavior of hydrogen and boron. The structure properties, bonding energy, energy band structure and density of states (DOS) of BH2, BH3, B2H6, SiH4 and AlH3 were calculated and analyzed using the CASTEP module in Materials Studio. The results show that BH2 has the feature of semiconductor, while BH3, B2H6, SiH4 and AlH3 belong to insulator. Additionally, the order of binding energy for hydrides from large to small is B2H6, BH3, SiH4, BH2 and AlH3, indicating that B2H6 is the most stable compounds among the hydrides. The DOS and partial density of states (PDOS) analysis show that the valence band of B2H6 contains four parts, which are contributed by H-1s and B-2s states, H-1s, B-2s and B-2p states, H-1s and B-2p states, H-1s and B-2p states, respectively. To verify the calculation results, an experiment and a thermodynamic analysis were carried out, and both of them proved that the calculation results agree well with the experimental results.

The dehydrogenation of Li4BN3H10 modified by Co is investigated by first-principles calculations using GGA-PW91 method within CASTEP. The calculation results show that Co modification may result in favorable H-desorption of Li4BN3H10 by reducing the hydrogen dissociation energy, due to the weaker B–H and N–H interactions, the formation of Co–B bond and the appearance of semiconducting nature in Li4BN3H10–Co. In addition, the B–N bond formed upon energetically favorable dehydrogenation may favor for Li4BN3H10 dehydrogenation. Although Co is a good catalyst for Li4BN3H10 dehydrogenation, Co doping in Li4BN3H10 bulk is energetically unfavorable with the occupation energy of 3.818 eV. The energy cost for Co dopant should be reduced for Co-doped Li4BN3H10 application.

[(Z)-2-((1,3-bis(diphenyl phosphaneyl) propylidene) amino) acetic acid/Zirconium oxide nanoparticles] composites thin film [DPPP + Gly/ZrO2]C is synthesized by utilizing physical vapor deposition (PVD) with a speed rate of 2000 rpm/30 s. The optimization of the samples was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. The [DPPP + Gly/ZrO2]C nanocomposite thin film is examined by different techniques including scanning electron microscope (SEM), X-ray diffraction (XRD), proton nuclear magnetic resonance (1HNMR), and Fourier transform infrared (FT-IR). The [DPPP + Gly/ZrO2]C nanocomposite thin film with the thickness (150 ± 5 nm) is fabricated at optimization conditions. The optical constants (refractive index, $$n\left(\lambda \right)$$ , extinction coefficient, $$k\left(\lambda \right)$$ , dielectric constants ( $${\epsilon }_{1}\left(\lambda \right)$$ and $${\epsilon }_{2}\left(\lambda \right)$$ ) and optical conductivity ( $${\sigma }_{1}\left(\lambda \right)$$ and $${\sigma }_{2}\left(\lambda \right)$$ )) for [DPPP + Gly/ZrO2]C nanocomposite thin film are computed and compared by using experiment and CATSTEP methods. The optical properties of simulated FTIR, XRD, and CATSTEP of the considered fiber nanocomposites are in somewhat compatible with the experimental study. The nano nanocomposite thin films present a promising result to be a good candidate for optoelectronics and solar cell applications.

A crystalline ((3-bromo-5-isopropyl-2-methyl-4-oxocyclohxa-2,5-dien-1-yl)methyl 4ʹ-hydroxy-5ʹ-isopropyl-2ʹ-methyl-[1,1ʹbiphenyl]-2-sulfonate) [BTB]Keto was synthesized in different media at 25 °C based on an oxidation method in the presence of potassium permanganate. The redox reactions occur in alkaline and acidic media. In alkaline medium, two distinct stages were observed: The first stage was relatively fast and the second stage was relatively slow. The first step coexists with the formation of intermediate complexes involving transient species relatively quickly of the blue hypomanganate (V) and green manganate (VI). The slowly decomposed intermediate formed to produce soluble colloidal manganese (IV) and the BTB keto-derivatives as second slow-stage oxidation products. But in acidic medium, oxidation reaction occurs in one stage because the first stage was found to be very fast and cannot be followed and the second stage was found to be slow so the reaction occurs in one stage (slow stage) to give rise to the final oxidation product [BTB]Keto. Thin films were produced through physical vapor deposition. Both the resulting dye particles and prepared thin films were deeply discussed using various techniques including Fourier transform infrared (FTIR), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and optical properties. DMol3 and Cambridge Serial Total Energy Package (CASTEP) program performed the optimization of the samples using density functional theory (DFT). An XRD and FT-IR study established the structural properties of the resultant dye. The XRD tests of thin films (monoclinic 2) display crystal structure. An optical measurement found that with growing photon energy the optical constants (refractive index n, absorption index k, dielectric constants, and optical conductivity) decreased. The optical properties of the dye thin films found in model FTIR, XRD, and CATSTEP are in strong alignment with the experimental research. The dye thin films show a compelling outcome to be a successful choice for applications in optoelectronics and solar cells. Experimental XRD data of both [BTB]TF and [BTB]keto thin films

BaAl2-2xLi2xSi2O8-2x (x = 0, 0.005, 0.0075, 0.01, 0.02, 0.03) ceramics were synthesized by solid-state sintering method. Based on density functional theory, the first-principle calculations provided by the Cambridge Sequential Total Energy Package (CASTEP) software were introduced to the BaAl2Si2O8 (BAS) system. In an effort to confirm the site occupied by Li+, we discussed the formation energy and final energy of different positions of Li+ doped BAS. The result demonstrated that Li+ should substitute Al3+ to promote the hexacelsian-to-celsian transformation with the aid of generated oxygen vacancies. The sintering behavior, crystal structure, surface appearance, and microwave dielectric properties of samples were investigated. Completely transformed celsian could be obtained when x = 0.005–0.03, which lowered the sintering temperature from 1400 °C (x = 0) to 1300 °C (x = 0.03), as well as strikingly improved the compactness, quality factor (Q × f) value and temperature coefficient of resonant frequency (τf) of BAS ceramics. When x = 0.1, unveiling the significant effects of Al-position ion substitution, BaAl1.98Li0.02Si2O7.98 ceramic sintered at 1350 °C for 5 h exhibited a supreme Q × f value of 48,620 GHz, and the er and τf values were 6.99 and -23.29 × 10−6 °C−1, respectively.

Poly(ortho-phenylenediamine) micro-rods (PoPD) are synthesized in the acidic medium at 25 °C by an oxidative polymerization method in the absence or the presence of a soft template including the following surfactants para toluene sulfonic acid (PoPD-PTS) and trisodium citrate (PoPD-TSC). Then, the thin films of poly(ortho-phenylenediamine) (PoPD)F, toluene sulfonic acid (PoPD-PTS)F, and trisodium citrate (PoPD-TSC)F are fabricated using the physical vapor deposition method (PVD). The fabricated thin films are characterized by several techniques includes Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), UV–Vis spectroscopy (UV–Vis), scanning electron microscopy (SEM), and optical properties are interpreted in-depth. The optimization for the samples is carried out by applying density functional theory (DFT) with DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. XRD measurements of thin film showed a crystal structure of monoclinic 2, and there is an increase of polymer crystallite size when used PTS and TSC surfactants in the preparation of the polymer. The study of surface morphology shows a smooth surface with uniform micro-rods for the resulting polymer. The optical constants including refractive index (n), absorption index (k) are calculated. Based on the optical measurements, the optical constants decrease with increasing photon energy while optical conductivity, and dielectric constants increase. Following the experimental analysis, the optical properties of simulated FT-IR, XRD, and CATSTEP are in good agreement with the experimental ones. (PoPD-PTS)F and (PoPD-TSC)F films are a good applicant for optoelectronics and solar cells.

In this study, the Castep module is used to construct and calculate eight configurations of the orthorhombic structure CH3NH3PbI3−x Br x (x = 0.00, 0.25, 3.00) as new energy materials. The Perdew, Burke and Ernzerhof version of the generalized gradient approximation functional is used to investigate the physical properties of the eight configurations. When x = 0.25, the most stable structure is determined by comparing the final energies of CH3NH3PbI2.75Br0.25 with those of different replaced positions. The CH3NH3PbBr3 structure exhibits the most stable structural frameworks among x = 0.00, 0.25 and 3.00. The energy band structure, density of states and optical absorption properties are calculated and plotted; these indicate that all materials are direct semiconductors with bandgaps ranging from 1.726 to 2.274 eV, and the bandgap increases as x increases. Furthermore, the substitutions at different sites change the intrinsic properties of the material and enhance the stability of the material, which provides a new viewpoint in materials technology.

The structural, elastic, electronic, vibrational, optical, thermodynamic, and superconducting properties of potentially technologically important superconductors CaIrSi3, CaPtSi3, LaIrSi3, and LaRhSi3 have calculated by using density functional theory (DFT) with CASTEP code. The investigated results are compared with available experimental and theoretical values. All the calculated values are well agreed with the experimental and theoretical values. The single elastic moduli for all the compounds show mechanical stabilities under the Born stability conditions. The ductility nature appears from the value of Pugh ratio. The band structure shows that the material behaves metallic nature. The overall superior discussion of charge density and charge density difference map reveals the ionic, covalent, and metallic nature of noncentrosymmetric superconductors. The Fermi surface shows the hole and electron-like sheets. Various optical parameters are also investigated. The different optical and thermodynamic properties have also been observed in the present study. The reflectance spectrum reveals that these compounds have the influence to be used as a proficient solar reflector. The analyzed minimum thermal conductivity denotes the low thermal conductivity at ambient conditions. The Debye temperature has also been evaluated by using present single elastic constants data. The detailed study of the superconducting parameter indicates the phonon-mediated medium coupled BCS superconductors. The acquired knowledge in the present inquiry could provide a prominent encouragement for future theoretical studies.

In this work, the structural, electronic and optical properties of Ce2S3 compound have been explored using CASTEP simulation code. We explore the crystal structure, lattice parameters, electronic band structure, the total density of states (TDOS), the partial density of states (PDOS) and the optical functions of the Ce2S3 compound using first-principles simulation based on density functional theory (DFT). The orthorhombic crystal structure with space group (Pnma) of Ce2S3 is stable both chemically and structurally. The lattice parameters of this compound are obtained by the optimization method. The lattice parameters measured in this study (a = 7.53 A, b = 4.10 A and c = 15.73 A) indicate excellent agreement with experimental and previous theoretical results. The electronic properties are investigated using Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and GGA observe U approaches within DFT employing CASTEP code. The energy bandgap value reported in this study (Eg = 0.76 eV) is comparable to the previous theoretical value. This energy bandgap value shows that Ce2S3 belongs to the semiconductor category. The frequency-dependent dielectric function and some optical properties such as reflectivity, absorption coefficient, optical dielectric constant, optical conductivity and the energy loss function have also been calculated in the present work. The optical reflectivity is noted to be maximum in the ultraviolet region of the electromagnetic spectrum.

First principles calculations are carried out to explore the structural, electronic and optical properties of Pure and Cd-doped BaZrO3, an oxide-based perovskite material. To investigate these properties, Ultra-soft pseudo-potential (USP) is used as incorporated in Cambridge Serial Total Energy Package (CASTEP). In this system, the generalized gradient approximation (GGA) proposed by Perdew-Burke Erzenhoff (PBE) is used for exchange correlation potential. Cadmium (Cd) doping at Ba-site is more favorable as compare to Zr-site because new gamma points occurred which not only affects the electronic structure of the BaZrO3 but also reduces the band gap from 3.127eV to 1.326eV and a transformation from indirect to direct band gap occurred. After doping, Fermi level shifted towards valance band which exhibits the characteristic of p-type semiconductor material. In optical properties, the absorption spectrum, refractive index (2.73), dielectric constants, reflectivity and energy loss function of the doped in comparison with pure material is presented. It has good optical response in UV region. The doping changes the optical behavior of BZO drastically thus making this material more effective for optoelectronic applications.

The study analyzed the optical response of GaAs 0.75 Sb 0.25 nanosheet under high pressure. It is the generalized gradient approximation (GGA) within the framework of density functional theory (DFT) was employed by means of a simulation program, which is called CASTEP. Under different pressure (P = 0, 2, and 4 GPa). Geometry optimized parameters were calculated for the nanosheet. The optical data alter in accordance with high pressure. The increase of pressure in the nanosheet led to a rise in p = 4 GPa and a decline in p = 2 GPa of the optical energy band gap, the static dielectric constant 𝜀 1 (0), and optical conductivity. The discussions of the real 𝜀 1 (𝜔) and imaginary 𝜀 2 (𝜔) sections of the dielectric function, optical band gap energy, optical absorption, and optical conductivity were included.

Room temperature ferromagnetism (RTFM) was observed in unirradiated ZnO single crystal owing to zinc vacancy (VZn) defects. D-D neutron irradiation was used to regulate the defect concentration and types avoiding interference of impurity elements. D-D neutron mainly collides elastically with ZnO single crystals, producing VZn, oxygen vacancy (VO), and other point defects, the density and kind of defect associated with neutron irradiation fluence. It can be found the saturation magnetization (Ms) first increases and then decreases with the irradiation fluence increases, meaning there is an optimum value for VZn concentration. When the neutron fluence is greater than 5× 109 n/cm2, more unstable VZn combined with VO to form zinc-oxygen divacancy (VZnO), indicating neutron irradiation changes the defect types. VZnO induces a smaller magnetic moment; thus, the Ms decreased. To further verify the origin of RTFM, the CASTEP module was employed to calculate the magnetic and structural properties of native vacancy defects in ZnO. VZn induces 2.12 μB magnetic moment, and only VZnO formed by the nearest VZn and VO has 2.09 μB magnetic moment, while 3VO cluster introduces a magnetic moment of $\sim $1 μB. Combined experiment and CASTEP calculation results, VZn is the most likely origin of RTFM.

A combined multinuclear solid state NMR and gauge included projected augmented wave, density functional theory (GIPAW DFT) computational approach is evaluated to determine the four heteronuclear 1J(13C,17O) couplings in solid 17O enriched naphthalaldehydic acid. Direct multi-field 17O magic angle spinning (MAS), triple quantum MAS (3QMAS) and double rotation (DOR) experiments are initially utilised to evaluate the accuracy of the DFT approximations used in the calculation of the isotropic chemical shifts (δiso), quadrupole coupling constants (CQ) and asymmetry (ηQ) parameters. These combined approaches give δiso values of 313, 200 and 66 ppm for the carbonyl (C[double bond, length as m-dash]O), ether (-O-) and hydroxyl (-OH) environments, respectively, with the corresponding measured quadrupole products (PQ) being 8.2, 9.0 and 10.6 MHz. The geometry optimised DFT structure derived using the CASTEP code gives firm agreement with the shifts observed for the ether (δiso = 223, PQ = 9.4 MHz) and hydroxyl (δiso = 62, PQ = 10.5 MHz) environments but the unoptimised experimental XRD structure has better agreement for the carbonyl group (δiso = 320, PQ = 8.3 MHz). The determined δiso and ηQ values are shown to be consistent with bond lengths closer to 1.222 Å (experimental length) rather than the geometry optimised length of 1.238 Å. The geometry optimised DFT 1J(13C,17O) coupling to the hydroxyl is calculated as 20 Hz and the couplings to the ether were calculated to be 37 (O-C[double bond, length as m-dash]O) and 32 (O-C-OH) Hz. The scalar coupling parameters for the unoptimised experimental carbonyl group predict a 1J(13C,17O) value of 28 Hz, whilst optimisation gives a value of 27 Hz. These calculated 1J(13C,17O) couplings, together with estimations of the probability of each O environment being isotopically labelled (determined by electrospray ionisation mass spectrometry) and the measured refocussable transverse dephasing (T2') behaviour, are combined to simulate the experimental decay behaviour. Good agreement between the measured and calculated decay behaviour is observed.

Room temperature ferromagnetism (RTFM) was observed in unirradiated rutile TiO2 single crystals prepared by the floating zone method due to oxygen vacancy (VO) defects. D–D neutrons mainly collide elastically with TiO2, producing VO, titanium vacancies (VTi) and other point defects; the density and kind of defect is related to the neutron irradiation fluence. D–D neutron irradiation is used to regulate the concentration and type of defect, avoiding impurity elements. As the irradiation fluence increases, the saturation magnetization (Ms) first increases, then decreases and then increases. To verify the origin of RTFM, the CASTEP module was used to calculate the magnetic and structural properties of point defects in TiO2. VO induces a 2.39 μB magnetic moment, Ti3+ and F+ induce 1.28 μB and 1.70 μB magnetic moments, respectively, while VTi induces a magnetic moment of ∼4 μB. Combining experimental and theoretical results, increases in VO concentration lead to Ms increases; more VO combine with electrons to form F+, inducing a smaller magnetic moment. VO and VTi play a key role and Ms changes accordingly with larger fluence. VO, F+ and VTi are the most likely origins of RTFM.

The construction of organic-inorganic hybrid ferroelectric materials with larger, high-polarity guest molecules intercalated in kaolinite (K) faces difficulties in terms of synthesis and uncertainty of structure-property relationships. The purpose of the present study was to optimize the synthesis method and to determine the mechanism of ferroelectric behavior of kaolinite intercalated with p-aminobenzamide (PABA), with an eye to improving the design of intercalation methods and better utilization of clay-based ferroelectric materials. The K-PABA intercalation compound (chemical formula Al2Si2O5(OH)4∙(PABA)0.7) was synthesized in an autoclave and then characterized using X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The experimental results showed that PABA expanded the kaolinite interlayer from 7.2 A to 14.5 A, and the orientation of the PABA molecule was ~70° from the plane of the kaolinite layers. The amino group of the PABA molecule was close to the Si sheet. The presence of intermolecular hydrogen bonds between kaolinite and PABA and among PABA molecules caused macro polarization of K-PABA and dipole inversion under the external electric field, resulting in K-PABA ferroelectricity. Simulation calculations using the Cambridge Sequential Total Energy Package (CASTEP) and the ferroelectricity test revealed the optimized intercalation model and possible ferroelectric mechanism.

The effect of CO and NO adsorption on graphene (pristine, vacancy and doped) were investigated for structural and electronic properties. The sensitivity of palladium (Pd) doped graphene toward small gas molecules CO and NO have been investigated by using DFT calculation within Generalized Gradient Approximation (GGA) as implemented in DMol3 and CASTEP. The density of states, the most stable adsorption site and adsorption energy of these small gas molecules on vacancy graphene and Pd-doped vacancy graphene are thoroughly discussed. It is found that Pd doping significantly enhances the strength of interaction between adsorbed molecules and the modified substrates. The most stable adsorption site for CO and NO on all graphene sheets are identified and reported. The results present the potential of vacancy graphene and Pd-doped vacancy graphene for molecules sensor application. Novelty • The novelty of this paper is the doping of Pd on vacancy graphene surface could enhance the adsorption energy of CO and NO gas molecules. • Besides, most of the studies not using Pd on vacancy graphene to study its effect on small molecules.

In this study, we report on a structural investigation of AND-1184, with the chemical name N-[3-[4-(6-fluoro-1,2-benzoxazol-3-yl)piperidin-1-yl]propyl]-3-methylbenzenesulfonamide (MBS), and its hydrochloride form (MBSHCl); AND-1184 is a potential API for the treatment of dementia. The single-crystal X-ray investigation of both forms results in monoclinic crystal systems with P21/c and C2/c symmetry for MBS and MBSHCl, respectively. This solid-state NMR study, combined with quantum-chemical calculations, allowed us to assign all 13C and most 1H signals. The MBS structure was defined as a completely rigid system without significant dynamic behaviours, whereas MBSHCl exhibited limited dynamic motion of the aromatic part of the molecule.

A detailed computational perspective, with CASTEP package having exchange correlation function GGA-PBE and USP (ultra-soft pseudopotential), to explore the structural stability, bandgap engineering and optical properties of beryllium (Be)-, magnesium (Mg)- and lithium (Li)-doped SrZrO3 is presented. The results of structural properties of SrZrO3 reveal that the partial replacement of Sr atoms with Li, Be and Mg atoms leads to decrease in lattice constants and hence volume of the unit cell. This decrease in lattice constants effects the electronic band structure and it decreases, after the doping of Mg and Be, from 3.313 to 1.863 eV and 0.906 eV, respectively. But after the doping of Li atoms, the increase in band gap (3.438 eV) is observed due to its strong polarization strength and limited scale. The nature of the band gap is changed from indirect to direct with Li-doping and remains same for Mg- and Be-doping and reason of band gap engineering is explained with PDOS, TDOS and elemental PDOS. The optical properties of pure and doped SrZrO3 are correlated with their electronic properties. The performance of modified electronic and optical properties of SrZrO3 after doping of Li, Be and Mg metals would be suitable in optoelectronic devices.

The X-ray absorption near edge structure (XANES) can provide uniquely detailed information on the coordination environments of important Ga-containing materials with unknown structures, including catalytically-active materials. In this study, the Ga K-edge XANES was simulated using first principles-based methods for seven molecular Ga complexes, as well b-Ga2O3, in order to explore the chemical origins of the experimentally observed features. The theoretical spectra were computed using FEFF, CASTEP and StoBE, in order to assess the sensitivity of the results to the computational approach. While the XANES features depend on the Ga coordination environment, they are also sensitive to the electronegativity of the ligands and the symmetry at Ga. The white line position responds to changes in both the core state (due to differential screening) and the valence “p” states (arising from differences in ligand coordination).

Copper oxide thin films were deposited by using pulsed DC magnetron sputtering system on glass substrates for various powers. The X-ray diffraction, optical spectroscopy, and SEM were used to characterize the physical and optical properties of films. Sputtered copper oxide films showed Cu2O and CuO phases. Copper oxide films deposited at 90 W were implanted with silver ions, which is one of the interesting methods to tune the electrical and optical properties of metal oxides. The optical and electrical properties of the films were also studied after ion implantation. The band gap, refractive index, and resistivity were found to be decreased after silver ion implantation. Furthermore, the influence of the silver (Ag) ion implantation on the optical properties of CuO and Cu2O was calculated using the density functional theory, with CASTEP code, which is complying with experimental trend. This study has revealed on the basis of the physical characteristics that CuO and Cu2O can be used as a suitable absorbent material in solar cells.

Isosymmetric structural phase transition (IPT, type 0), in which there are no changes in the occupation of Wyckoff positions, the number of atoms in the unit cell, and the space group symmetry, is relatively uncommon. Chlorothiazide, a diuretic agent with a secondary function as an antihypertensive, has been proven to undergo pressure-induced IPT of Form I to Form II at 4.2 GPa. For that reason, it has been chosen as a model compound in this study to determine if IPT can be predicted in silico using periodic DFT calculations. The transformation of Form II into Form I, occurring under decompression, was observed in geometry optimization calculations. However, the reverse transition was not detected, although the calculated differences in the DFT energies and thermodynamic parameters indicated that Form II should be more stable at increased pressure. Finally, the IPT was successfully simulated using ab initio molecular dynamics calculations.

Dapsone is a sulfonamides drug used to treat various types of leprosy and skin diseases. The temperature dependent absorption spectra of dapsone in the range of 0.3 to2.1THz were obtained. The Gaussian and CASTEP software was used respectively for molecular and crystal calculation of dapsone. The experimental results were compared with the calculated results, and the differences were analyzed in this study.

We report a combined experimental and theoretical study of pure and doped cobalt ferrite where 25% of Fe3+ ions were replaced by Al3+, Ga3+, and In3+ ions, respectively, i.e., CoFe1.5X0.5O4 (X = Al, Ga, and In). The ferrite compositions were successfully synthesized using the solid-state reaction method. The X-ray powder diffraction method established that all ferrite samples had a spinel unit cell structure with the Fd3[combining macron]m (No. 227) space group. The lattice constants of ferrites increased from 8.382 A (for undoped CoFe2O4) to 8.520 A (for In-doped cobalt ferrite) in direct relation to the dopant ion size. The magnetic properties were obtained at 4.3 K and 300 K. At 4.3 K, the In-doped CoFe2O4 showed the highest saturation magnetic moment of 4.68 μB f.u.-1, while Al-doped CoFe2O4 showed the smallest value of 2.72 μB f.u.-1. The Fe3+ distribution among the spinel tetrahedral and octahedral sites was determined from the Mossbauer spectra. From ultraviolet-visible diffuse reflectance spectroscopy the direct optical bandgaps were determined, which have values between 1.20 eV and 1.28 eV for these ferrites. The ferrite compositions were also studied theoretically using plane-wave density functional theory using the CASTEP code where it was revealed that arrangements of the non-magnetic cations at the tetrahedral and octahedral sites strongly influence the electronic structure, the bandgap value, and the net magnetic moment per formula unit. Light Al3+ ions at the octahedral site give a low value of the net magnetic moment while the heavier Ga3+ and In3+ ions at the tetrahedral sites of the spinel give an enhanced magnetic moment. The magnetic moment values obtained from theoretical calculations match very well with the experimental values. Moreover, the theoretical calculations reveal that there exists a strong p-d hybridization among the oxygen and magnetic ions, which is affected by the non-magnetic dopant ions. The change in hybridization with the non-magnetic ion doping is responsible for the altered magnetic moments of the doped ferrites. Thus, our study provides a comprehensive investigation covering the synthesis and characterization of ferrites along with a good understanding of the phenomenon of how non-magnetic ion doping into spinel ferrites provides a method to tune the electronic and magnetic properties of the spinel ferrite.

In this chapter, We looked into the optical propertiessuch as refractive index n(ω), absorption coefficient α(ω), and dielectric constant of wurtzite (WZ) GaN semiconductor using the plane-wave pseudopotential method within density functional theory (DFT). The optical phonon modes were also calculated at 0 GPa utilising phonon calculation on Cambridge Serial Total Energy Package (CASTEP) software. All of the aforementioned parameters' calculated values are compared with available experimental values and the values reported by different workers. They have reached a fairly good agreement.

Indium and bismuth are technologically important elements, in particular as oxides for optoelectronic applications. 115In and 209Bi are both I = 9/2 nuclei with high natural abundances and moderately high frequencies but large nuclear electric quadrupole moments. Leveraging the quadrupolar interaction as a measure of local symmetry and polyhedral distortions for these nuclei could provide powerful insights on a range of applied materials. However, the absence of reported NMR parameters on these nuclei, particularly in oxides, hinders their use by the broader materials community. In this contribution, solid-state 115In and 209Bi NMR of three recently discovered quaternary bismuth or indium oxides are reported, supported by density functional theory calculations, numerical simulations, diffraction, and additional multinuclear (27Al, 69,71Ga, 121Sb) solid-state NMR measurements. The compounds LiIn2SbO6, BiAlTeO6, and BiGaTeO6 are measured without special equipment at 9.4 T, demonstrating that wideline techniques such as the QCPMG pulse sequence and frequency-stepped acquisition can enable straightforward extraction of quadrupolar tensor information in I = 9/2 115In and 209Bi even in sites with large quadrupolar coupling constants. Relationships are described between the NMR observables and local site symmetry. These are amongst the first reports of the NMR parameters of 115In, 121Sb, and 209Bi in oxides.

In order to reveal the fouling problem on the outer surface of the steam generator (SG) tube in the secondary circuit condition of pressurized water reactor (PWR) nuclear power plant, based on the density functional theory (DFT) method, the Cambridge sequential total energy program package (CASTEP) is used to simulate seven kinds of highly symmetric adsorption structure models of termination with tetrahedral Fe (A termination) and termination with octahedral Fe (B termination) on Fe3O4 (0 0 1) surface. The adsorption energies and stable adsorption conformations are calculated. The results show that the most stable adsorption structures of the Fe2+/Fe3O4 (0 0 1) configurations are Fe2+ above Fe-O bond of B layer termination (Fe3O4(001) A-b). During the adsorption, the Fe-Fe, Fe-O bond length, and Fe-Fe-O bond angle of (0 0 1) surface change, and the atomic positions parallel and perpendicular to (0 0 1) surface change correspondingly. The change happened to the surface layer is the most drastic one. The calculation of charge population, the density of states (DOS), and electron local function of Fe2+/Fe3O4 (0 0 1) optimal adsorption configuration show that there is electron transfer between Fe2+ and Fe3O4 (0 0 1), and the adsorption type is chemisorption. Among them, Fe (Fe2+)-Fe (Fe3O4) forms a metal bond, and Fe (Fe2+)-O (Fe3O4) forms the ionic bond. The results illustrate the interaction between free Fe2+ and Fe3O4 is the reason of the nucleation and agglomeration of Fe3O4 scale and it provides the foundation for the further research on Fe3O4 scale deposition.

Electronic band structure and elastic and optical properties are studied for the solid-state $\mathbf{CdTe}_{1-x}\mathbf{Se}_{x}(x=1/16$ and 15/16) solutions, using a density functional theory and a CASTEP code. The structures of the samples are deduced issuing from the ‘parent’ compounds $\mathbf{Cd}_{16}\mathbf{Te}_{15}$ and $\mathbf{Cd}_{16}\mathbf{Se}_{16}$ . A cubic structure of the ‘parent’ compounds is taken. The bandgap of $\mathbf{CdTe}_{1-x}\mathbf{Se}_{x}$ is found to be of a direct type for all of the solid-state solutions under test. Basing on the electronic band structure, we obtain the effective electron mass, the effective masses of holes corresponding to different energy levels, and the reduced carrier mass at the $\mathbf{G}$ point of Brillouin zone. The optical parameters such as exciton-binding energy, refractive index and high-frequency dielectric constant are calculated, too. The elastic properties such as the Young, shear and bulk modules are predicted, along with and the Poisson ratio. Using the data for the elastic coefficients, the acoustic velocities and the Debye temperature are obtained. All of the calculated parameters correlate well with the known experimental data.

Hu et al. reported the hydrogen storage properties of Sc2C and Ti2C based MXene phases utilizing density functional theory (DFT) as implemented in the CASTEP code [1, 2]. Based on such calculations, the authors suggest that the MXenes should be a new family of potential hydrogen storage media. Their results claim a maximum hydrogen storage capacity of 9.0 wt% with an average binding energy of 0.164 eV/H2 in Sc2C MXene indicating Kubas-type interaction between H2 and the MXene. These investigations are of prime importance since they provide insight about further applications of MXenes for hydrogen storage. In these calculations they have used local density approximation (LDA) to estimate the adsorption energies. However, binding energies for H2 with the MXene phases mentioned above obtained from more accurate calculations based on Generalised Gradient Approximation (GGA) and calculation including dispersion correction (GGA + vdW) show very weak binding energy ( ∼ 0.064 e V / H 2 ) suggesting weak physical interactions between H2 and the MXene phases. Our accurate DFT calculations predict that these MXene phases are not suitable for hydrogen storage at realistic conditions. So we conclude that appropriate exchange-correlation functional should be used to extract hydrogen adsorption energies in nano-phases to describe their hydrogen storage properties reliably.

The Raman scattering spectra for the MnPS3 single crystal have been studied at frequencies ranging from 5 to 1200 cm−1, for temperatures ranging from 5 to 295 K. This is the first time that studies of low-temperature polarized Raman spectra in a magnetically ordered phase are presented for MnPS3. Energy splitting between some of Ag- and Bg-modes, which were previously believed to be energy equivalent in crystals from this family, has been found. The nature of the additional phonon lines observed in the Raman scattering spectra is discussed. It is found that at low temperatures, the magnetic scattering spectrum has a complex form that is related to the presence of both two-magnon and a phonon-magnon bands. The vibrational properties of the MnPS3 crystal were calculated using the LDA approximation with the DFT-D (OBS) dispersion correction implemented in the CASTEP computation package. Phonon dispersion curves and the total and partial phonon densities of states have been calculated in the antiferromagnetic phase of the MnPS3 crystal. The calculated results are in good agreement with the experimental Raman spectra.The Raman scattering spectra for the MnPS3 single crystal have been studied at frequencies ranging from 5 to 1200 cm−1, for temperatures ranging from 5 to 295 K. This is the first time that studies of low-temperature polarized Raman spectra in a magnetically ordered phase are presented for MnPS3. Energy splitting between some of Ag- and Bg-modes, which were previously believed to be energy equivalent in crystals from this family, has been found. The nature of the additional phonon lines observed in the Raman scattering spectra is discussed. It is found that at low temperatures, the magnetic scattering spectrum has a complex form that is related to the presence of both two-magnon and a phonon-magnon bands. The vibrational properties of the MnPS3 crystal were calculated using the LDA approximation with the DFT-D (OBS) dispersion correction implemented in the CASTEP computation package. Phonon dispersion curves and the total and partial phonon densities of states have been calculated in the antiferromagnetic...

The structural, elastic and electronic properties of Nb-Cr-Si based alloys have been investigated by employing first-principles calculations from CASTEP program based on density functional theory (DFT). The calculated lattice parameters of Nb-Cr-Si based alloys are in good agreement with the experimental values. The elastic constants of NbCrSi are calculated. The bulk modulus, shear modulus, Young's modulus and Poisson's ratio of NbCrSi are obtained, which show that NbCrSi lies on the borderline of ductile to brittle transitions. Furthermore, all Nb-Cr-Si based alloys considered in this work are conductive phases.

A non-rare-earth doped double perovskite La2ZnTiO6:Mn4+ phosphor with the single-phase was prepared by solid-state reaction. The composition and the distribution of La2ZnTiO6:0.5%Mn4+ phosphor was confirmed by the scanning electron microscope and energy-dispersive spectroscopy. The optical band gap of La2ZnTiO6 was analyzed by density functional theory using the CASTEP code, which matched well with the result of diffuse the reflectance spectra (DRS). The excitation spectra of La2ZnTiO6:Mn4+ show two broad bands with peaks at about 342 nm and 504 nm. Emissions characteristic of Mn4+ ions from 650 nm to 750 nm were observed, with the 4Eg→4A2g transition near 708 nm. The result of the temperature-dependent photoluminescence shows good thermal stability and the luminous mechanism is explained by schematic energy level diagram of Mn4+ ion. Above all, a significant overlap was found between the far-red emission band of La2ZnTiO6:0.5%Mn4+ and the absorption spectrum of the phytochrome PFR, indicating that La2ZnTiO6:Mn4+ phosphor has great potentiality to be used as indoor plant artificial light.

Simultaneous combination of photocatalytic oxidation of tetracycline (TC) and reduction of Cr(VI) over the AgI/BiVO4 p-n junction photocatalysts were studied systematically. The result showed that the pollutant degradation efficiency of the photocatalyst was greatly enhanced when the system contained both TC and Cr(VI) compared to that containing Cr(VI) or TC alone. It is proposed that the co-existence of oxidizable and reducible species, such as TC and Cr(VI), ensured efficient use of the photoinduced electrons and holes, which leaded high efficiencies for both TC oxidation and Cr(VI) reduction. Among these photocatalysts, the 0.3-AgI/BiVO4 exhibits excellent photocatalytic activity, which is ascribed to the increased lifetime of the charge carriers confirmed by the result of time-resolved fluorescence emission decay spectra. In addition, seven degradation products of TC were found by GC–MS. Moreover, the band structure of the photocatalyst was obtained by the DFT calculation, VB-XPS spectra and the values of the Fermi level obtained by CASTEP. Finally, simultaneous photocatalytic oxidation and reduction enhancing mechanism over the AgI/BiVO4 photocatalyst was discussed in detail. The strategy of forming novel p-n junction photocatalyst for both the Cr(VI) reduction and TC oxidation will benefit the development of the other new photocatalysts for the purpose of controlling and improving the environment.

In this paper, the functions of enthalpy, entropy, free energy and heat capacity with temperature from 0 to 1800K and pressure from normal (101.325 KPa) to 80Gpa are obtained by the calculation of CASTEP module based on density functional theory (DFT) and compared with the corresponding values from manual thermodynamics data. Besides, the thermodynamic parameters such as enthalpy changes, entropy of various phases at different pressures and temperatures for the reaction of 2NaAlSi2O6 → NaA1Si3O8 + NaAlSiO4 are calculated and the Gibbs free energy of the reaction is gotten. Furthermore, the Gibbs free energy as a function of both temperature and pressure is presented with the three-dimensional graph by surface fitting. The calculation results show that the calculated values of the thermodynamic parameters are consistent with the data in the manual and the error values of that are less than or equal to 1%. In addition, there is a transition between endothermic and exothermic at 450 K under normal pressure. Compared with high temperature and low pressure or high temperature and high pressure, ΔrG is closer to zero at low temperature and high pressure (60 Gpa, near 400 k), at the same time, the phase stability is better.

A set of ZnMoO4 polycrystalline samples was synthesized by solid state reaction method and characterized by XRD structural analysis, ICP elemental analysis, SEM-EDX analysis, UV–Vis diffuse reflectance spectroscopy. The photoluminescence (PL) properties of ZnMoO4 samples were studied in 8–300 K temperature range with use of synchrotron radiation as an excitation source. The geometry-optimized electronic structure calculations of perfect and defective ZnMoO4 crystals were carried out by the DFT-based band-structure methods, plane-wave pseudo-potential (CASTEP program package) and FP-LAPW (Wien2k package). A number of point defects which can influence the luminescence properties of ZnMoO4 was considered in calculations, namely the oxygen vacancy Vo, compensated vacancies Vo + VZn, tungsten impurity WMo and the MoO3-deficient phase Zn3Mo2O9. Comparative analysis of experimental data and calculation results allowed explanation of the origin of the red and blue-green luminescence emission bands of ZnMoO4 as well as formation of their excitation spectra. It is assumed that the green component of ZnMoO4 luminescence emission, like in other molybdates of MIIMoO4 family (MII = Ca, Sr, Cd, Pb) originates from radiative annihilation of excitons self-trapped on regular MoO4 groups. The Red component of ZnMoO4 emission has a defect-related origin and it originates from radiative transitions in MoO4 groups located near oxygen vacancies.

Using the CASTEP module in Materials Studio software, the native defect model structures including O vacancy and Al vacancy in Al2O3(110) surface were designed and constructed. Through first-principles based on density functional theory (DFT) and pseudo potential method, the Al2O3(110) model structures were optimized. Formation energy, energy state structure, electric density and electron population of defect structures and primitive cell were calculation. Effect of O vacancy and Al vacancy on Al2O3 properties could be analyzed and probed. The results showed that formation energy of O vacancy is only 0.06 eV, which is significantly less than that of Al vacancy (2.99 eV). This indicates that the formation of O vacancy is more easily to produce. O vacancy defects reduce electronic energy in Al2O3(110), and make its conductivity become poorer. The impact of Al vacancy defects on conductivity are opposite. The influence of aluminum vacancy defects on electron density in Al2O3(110) is more than that of oxygen vacancy; oxygen vacancy increases the electronegativity around O atoms, and weakens electropositivity around Al atoms the electricity, which makes the top of energy band structure move down. The calculation results provide a theoretical guidance for the formation of functional anodic oxidation films of Al.

International audience; A combination of high field solid-state MAS NMR spectroscopy, X-ray diffraction, and firstprinciples calculations is used to elucidate the crystalline structure of CsSc3F10. At room temperature, this phase was found to crystallize in the Pmma (n°51) space group with a = 8.0837(1) Å, b = 7.5764(1) Å, and c = 6.8127(1) Å. The remarkable feature of CsSc3F10 is an unusual high cesium coordination number of 18. 45 Sc-19 F D-HMQC NMR method has been employed to investigate the connectivity of scandium with fluorine atoms. NMR parameters were determined using first principle DFT calculations and compared with experimentally obtained data.

Herein, we demonstrate the successful construction of a novel flowerlike Ag/p-Ag2O/n-BiVO4 plasmonic photocatalyst for the photocatalytic oxidation of BPA and reduction of chromium(VI) simultaneously under visible light irradiation. Among these samples, 2mM-Ag/p-Ag2O/n-BiVO4 exhibits the highest photocatalytic performances. The photocatalytic reduction and oxidation efficiency can achieve 69.8 and 91.9%, respectively, after 100 min visible-light irradiation. The enhancement mechanism for the plasmonic photocatalyst is explored, which can be attributed to the enhanced absorbance in the visible light region, and the facilitated charge transfer and the suppressed recombination of electron-hole pairs in the Ag/p-Ag2O/n-BiVO4. The results of the electrochemical impedance spectroscopy, the fluorescence emission spectra and the time-resolved fluorescence emission decay spectra indicate the enhanced charge separation in the Ag/p-Ag2O/n-BiVO4 plasmonic photocatalyst. In addition, the free radical scavenging test shows that h+ and OH radicals play crucial roles in the photocatalytic oxidation reaction. The photogenerated electrons in the photocatalytic reduction process, are confirmed by the DMPO spin-trapping technology. Moreover, the band structures of various photocatalysts are revealed via the valence band XPS spectra and the Fermi level obtained by CASTEP code.

Using ab initio technique the physical properties of ScIr2 superconductor have been investigated with Tc 1.03 K with a MgCu2-type structure. We have carried out the plane-wave pseudopotential approach within the framework of the first-principles density functional theory (DFT) implemented within the CASTEP code. The calculated structural parameters confirm a good agreement with the experimental and other theoretical results. Using the Voigt-Reuss-Hill (VRH) averaging scheme the most important elastic properties including the bulk modulus B, shear modulus G, Young’s modulus E and Poisson’s ratio ν of ScIr2 are determined. At ambient condition, the values of Cauchy pressure and Pugh’s ratio exhibit ductile nature of ScIr2. The electronic and optical properties of ScIr2 were investigated for the first time. The electronic band structure reveals metallic conductivity and the major contribution comes from Ir-5d states. In the ultraviolet region the reflectivity is high up to 50 eV as evident from the reflectivity spectrum.

The properties and characteristics of graded Al component Ga1-xAlxAs/GaAs photocathode are investigated in this paper, especially the transient reflectivity of Ga0.37Al0.63As under the condition of femtosecond laser illumination. Using software CASTEP, we calculate and analyze the optoelectronic property of varied Al composition Ga1-xAlxAs photocathode based on first principle theory. Ga0.37Al0.63As is emphasized studied because its lattice constant is very close to GaAs, reducing the probability of lattice mismatch and the back interface recombination velocity on the interface of substrate and emission layer. In this work, we design two reflection mode GaAs photocathode samples with different doping method: uniform-doping and exponential-doping used in emission layer grown by MBE. The impacts of different doping method on photocathode are analyzed by comparing some typical performance parameters. Transient reflectivity rates of different doping method Ga1-xAlxAs/GaAs photocathode are investigated by the device of pump-probe transient reflectivity system in the paper and we found that the way of exponential-doping is better for improving the performance of Ga1-xAlxAs /GaAs photocathode. The potential value of transient property of photocathode is enormous in future.

By means of density functional theory (DFT) calculations, we have systematically investigated the effect of hydrostatic pressure on the structural, electronic and elastic properties of barium-doped silicon clathrate Ba8Si46 in the type-VIII structure (α phase). Physical properties are calculated under different conditions of pressure (0 GPa to 45 GPa) using the GGA-PBE functional. Those calculations have been performed using the Cambridge serial total energy package CASTEP within the Materials Studio package. Electronic properties have shown that type-VIII Ba8Si46 has metal-like properties with a fundamental bandgap of 1 eV. Under pressure the fundamental bandgap increases slightly and the positions of the valence band maximum VBM and the conduction band minimum CBM remain unchanged when pressure is changed from 0 to 25 GPa, but when pressure is set to 30 GPa the CBM is transited from its initial position (Γ-H segment) towards the Γ(0,0,0) point, this indicates that the bandgap nature of this material can be tuned through strain engineering. We found that the compound is mechanically stable under the pressure range and might be unstable or collapse when pressure exceeds 44 GPa. These findings need to be confirmed experimentally through synthesis, a comparison with the type-I and the guest-free counterparts has exhibited promising features for the type-VIII Ba8Si46.

Under the first-principles framework, this paper used the CASTEP program to theoretically calculate TiN, TiC, and its intermediate compounds and therefore obtain a theoretical basis for their application. In this paper, the N atoms in the NaCl-type unit cell of TiN were replaced, and the atoms of TiN1-xCx (x = 0.25, 0.5, and 0.75) were constructed by replacing N with C atoms. The unit cell structure of the ternary compound TiN1-xCx (x = 0.25, 0.5, and 0.75) was constructed by replacing N with C atoms. In a subsequent step, these compounds were geometrically optimized and their properties were calculated. These compounds were subsequently subjected to geometric optimization to calculate their properties. By analyzing the electronic structure of the materials, it was found that TiN1-xCx exhibited metallic properties. In addition, this paper focused on the optical properties of TiN1-xCx ternary compounds under different compositions including absorption, reflectivity, refractive index, and photoconductivity. The accuracy and reliability of the theoretical results presented herein were confirmed by comparing current theoretical results with existing experimental or theoretical results.

The optical and luminescence properties of La3Ga5SiO14 lanthanum–gallium silicate crystals grown in atmospheres of argon and argon with the addition of oxygen are investigated. The results of calculations of the structure of energy bands are presented, obtained using the CASTEP module in the framework of the generalized gradient approximation and the local density approximation. The width of the optical band gap of the crystal is determined to be $$E_{g}^{{{\text{opt}}}}$$ = 5.1 eV. Upon interband excitation, La3Ga5SiO14 crystals grown in argon atmosphere show a luminescence band with a maximum at 430 nm, whereas for a crystal grown in argon with addition of oxygen, two luminescence bands with maxima at 470 and 530 nm dominate in the luminescence spectrum. The nature of the luminescence centers responsible for these bands is discussed with the help of the data for electronic structure calculations. The effect of temperature on the luminescent properties of La3Ga5SiO14 is demonstrated. The presence of traps in La3Ga5SiO14 is shown using thermally stimulated luminescence, and their activation energy is determined.