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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.

The compound 1-Isoquinolinyl phenyl ketone (1IPK) was studied theoretically as a corrosion inhibitor by quantum mechanics calculations and docking models. Density functional theory (DFT) of B3LYP/6-311G (d,p) and parameterization model 3 (PM3) using the Gaussian-09 and CASTEP programs was also employed to discuss the inhibition ability. Molecular graphic laboratory (MGL) tools program and discovery studio visualizer (DSV) used to estimate the ability for inhibition Acidithiobacillus Ferrooxidans (AF) bacteria, which is responsible for the corrosion. The calculations of physical properties and quantum chemical parameters correlated to the inhibition efficiency and discussed at the equilibrium geometry. The results indicated that the 1-Isoquinolinyl Phenyl Ketone could be adsorbed on the mild steel surface firmly through the nitrogen atom on the isoquinoline rings and the carbonyl group. Besides, the moderate values of parameters describe the low-efficiency of inhibition in acidic and saline medium. Total electron density (TED) and electrostatic surface potential (ESP) Figures showed the active site that is involved in the inhibition processes. In addition, the adsorption types were studied by different parameters.

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.

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.

Oxidation of bromothymol blue [BTB] by oxyanion potassium permanganate as a strong oxidizing agent in acid solutions using perchloric acid at a constant ionic strength has been obtained keto bromothymol blue [BTB]Keto and studied kinetically spectrophotometrically. Different characterization techniques for [BTB] and [BTB]Keto such as Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), and optical properties have been used. The order about the permanganate ion is first, while a fractional first order was released as regards [H+] and [BTB] fractional first order. Dependence on the concentration of hydrogen ions in the concentrations indicates that the oxidation process is acid catalyzed. The absence of either transient MnIII and/or MnIV as involving species in the oxidation process was verified by MnII applied to the oxidation reaction. Formation of 1:1 intermediate complex formation kinetically was revealed during the rate-determination step. In the slowest step, two-electron transfer processes of the inner-sphere form have been proposed. A mechanism of the tentative reaction was proposed and explored concerning kinetic parameters. The density functional theory (DFT) by DMol3 and CASTEP was used for the optimization of dye [BTB] and [BTB]Keto as an isolated molecule. From the UV–Vis spectrum of [BTB] and [BTB]Keto, the $$E_{\text{Direct}}^{\text{Opt}}$$ values are 2.849 eV and 2.35 eV using Tauc`s equation, respectively, related to direct transitions of electrons. Using DMol3 method with DFT simulation, the HOMO and LUMO values for [BTB] and [BTB]Keto as isolated molecule are 3.047 eV and 2.869 eV, respectively. The simulated FTIR, molecular electrostatic potential (MEP) and optical properties by Gaussian software and CATSTEP are in great agreement with the experimental study.

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.

A novel hydrolytic stable CoII–organic framework, namely poly[[bis(2-amino-4-sulfonatobenzoato-κO1)tetraaquatris{μ-1,4-bis[(imidazol-1-yl)methyl]benzene-κ2N3:N3′}dicobalt(II)] tetrahydrate], {[Co(C7H5NO5S)(C14H14N4)1.5(H2O)2]·2H2O}n, (1), based on multifunctional 2-amino-5-sulfobenzoic acid (H2asba) and the auxiliary flexible ligand 1,4-bis[(imidazol-1-yl)methyl]benzene (bix), was prepared using the solution evaporation method. The purity of (1) was confirmed by elemental analysis and powder X-ray diffraction (PXRD) analysis. Complex (1) shows a novel 1D→2D interpenetrating network, which is further extended into a 3D supramolecular framework with channels occupied by the lattice water molecules. The 2-amino-4-sulfonatobenzoate (asba2−) ligand adopts a monodentate coordination mode. The bix ligands exhibitgauche–gauche(GG) andtrans–trans(TT) conformations. A detailed analysis of the solid-state diffuse-reflectance UV–Vis spectrum reveals that an indirect band gap exists in the complex. The band structure, the total density of states (TDOS) and the partial density of states (PDOS) were calculated using theCASTEPprogram. The calculated band gap (Eg) matches well with the experimental one. The complex exhibits a reversible dehydration–rehydration behaviour. Interestingly, gas sorption experiments demonstrate that the new fully anhydrous compound obtained by activating complex (1) at 400 K shows selective adsorption of CO2over N2. Complex (1) retains excellent framework stability in a variety of solvents and manifests distinct solvent-dependent fluorescence properties. Moreover, the complex shows multiresponsive fluorescence sensing for some nitroaromatics in aqueous medium.

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.

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 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.

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.

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.

In this paper, the CASTEP program and machine learning algorithm are used to study Pmn21-BxAl1-xNyP1-y. The mechanical stability, thermodynamic stability and molecular dynamics stability of several typical structures of Pmn21-BxAl1-xNyP1-y are estimated by CASTEP program. The results show that all the structures are stable. The data such as lattice constants and elastic properties of Pmn21-BxAl1-xNyP1-y are used as training sets of machine learning, then, the average absolute percent error (MAPE) of each model is calculated by using 7-fold cross-validation, and the lattice constant prediction model and shear modulus prediction model of Pmn21-BxAl1-xNyP1-y are selected respectively. Linear regression algorithm is used for modeling lattice constants, and Xgboost algorithm is used for modeling shear modulus. On the test sets, it is found that the error is within the acceptable range by comparing the data predicted by the models with the real data. Therefore, the machine learning prediction models of lattice constants, and shear modulus G have strong generalization ability. The electrical properties of Pmn21-BxAl1-xNyP1-y are calculated by using hybrid PBE0 functional. The direct band gaps are found in AlN, BP, AlP, B0.25Al0.75N, B0.75Al0.25P, B0.5Al0.5P, B0.25Al0.75P, AlN0.75P0.25, AlN0.5P0.5 and AlN0.25P0.75.

Acyclovir, an antiviral purine derivative listed on the WHO's Model List of Essential Medicines, is commonly used in several different dosage forms from tablets to gels, oleogels and suspensions. Although temperature driven phase transitions of its commercially available 3 : 2 hydrate have been known since 2011, information on the solvent driven phase transitions of this drug has been limited. This study identifies the pathways of transformations of acyclovir forms I and V induced by organic solvents and water using the method of solution mediated phase transformation. The 3 : 2 hydrate, form V, undergoes dehydration to anhydrous form I in methanol, ethanol and N,N-dimethylformamide. Form I converts to anhydrous form II in dry methanol and N,N-dimethylformamide, while increased water content in the solvent prevents the transformation of form I to form II. Both forms I and V yield a gel-like material in dimethyl sulfoxide, composed of highly crystalline form II and reported here for the first time. Furthermore, significant differences in the thermal dehydration process of forms V and VI were observed using VT FTIR, including the first time report on a novel metastable ACV form VII formed upon dehydration of ACV dihydrate (form VI). High resolution solid-state NMR spectra of two anhydrous polymorphs (forms I and II) and two hydrates (forms V and VI) supported by DFT calculations using the CASTEP code are also presented.

CH3NH3PbI3 system of organic-inorganic hybrid perovskite structure solar cells absorption material was established by using first-principle calculations based on density functional theory (DFT). Orthorhombic CH3NH3PbI3 system model is optimized by different functional theories of CASTEP in Materials Studio. It revealed that the results of WC/GGA calculation method are more close to the experimental value. Electron band structure, state density are calculated in the paper and the results indicated that top orbital of the valence band is mainly contributed by Pb atom and I atomic orbital. At the same time, the conduction band bottom is mainly contributed by the orbital contribution of Pb atoms and strong σ bond is formed between terminal iodine atom and Pb atomic orbital. Moreover, the contribution of organic element density of states near the Fermi surface is very weak and the band gap of organic-inorganic hybrid CH3NH3PbI3 materials is basically determined by inorganic elements.

As transition metal silicides have been successfully synthesized, the study of the combination of transition metal and silicon is another effective way to investigate the properties of silicide. We recover novel structures of two silicides: MSi (M = Tc, Re). The structures phase are ɛ − F e S i phase (P213) and CsCl phase (Pm3m). Using the Cambridge Serial Total Energy Package (CASTEP) code, we researched the mechanical, electronic and optical properties of MSi (M = Tc, Re) under 0 GPa and 100 GPa. It is found that each structure is dynamically and mechanically stable at 0 GPa, and the Vickers hardness values show that all of them belong to soft materials. Besides, both the P213-MSi and Pm3m-MSi have metallic characters under 0 GPa and 100 GPa. For the reflectivity in the optical properties, it can be observed that the atom and pressure have obvious influence on the reflectivity of Pm3m-MSi, while only the pressure has obvious influence on the reflectivity of P213-MSi. We hope our work will provide some help to the experimental work on the technologically material.

The structural, electronic, elastic and thermodynamic properties of oxo- and thio-spinels have been predicted based on the ultrasoft pseudo-potential scheme as implemented in the CASTEP code. The exchange-correlation potential was treated within the generalized gradient approximation (GGA-PBE). The calculated structural parameters such as lattice constants and internal parameters are in good agreement with the available experimental data. The ground state electronic band structure revealed that CuAl 2X4 (X O, S) spinels are direct band gap semiconductors with a transition along Г-Г symmetry points. The calculated values of elastic constants satisfy the Born criteria at ambient conditions and confirm that the spinel structures of CuAl2O4 and CuAl2S4 are mechanically stable. The thiospinel structure may have a phase transition under pressure, due to the negative value of C44. The influence of temperature and pressure on macroscopic characteristics of CuAl2O4 and CuAl2S4 compounds was estimated using the quasi-harmonic Debye model.

This work presents a comprehensive spectroscopic analysis of crystalline isoniazid, one of the main drugs in tuberculosis chemotherapy, using a blend of spectroscopic and computational methods. Mid- and far-infrared, Raman, and inelastic neutron scattering spectroscopies, with contribution of isotopic substitution are combined with discrete and periodic DFT quantum chemical calculations. This combined approach successfully reproduces the whole spectral range, allowing a sound assignment of all the vibrational bands. Previous misassignments have been corrected and several spectral features of isoniazid crystal are reported for the first time. Virtues and limitations of the computational approach (periodic and discrete) are also discussed in light of the present state-of-the-art in the field.

Density functional theory (DFT) has become an engine for driving ab-initio quantum mechanical simulations spanning a vast range of applications. However, conventional DFT has limitations of the accessible system size due to computational expense. Recent progress on linear scaling DFT methods has enabled us to investigate larger systems. In this paper, we investigate the numerical agreement between conventional DFT codes and ONETEP, a linear-scaling DFT code, for important materials properties particularly calculating the intercalation potential of spinel electrode materials. Modulating materials with high energy density is an important aspect that contributes to the significant gap in our knowledge of the factors. We provide typical simulation results based on calculated intercalation potentials for discharging the spinel LixMn2O4, which plays a key role in developing high energy density lithium-ion batteries. The structural properties obtained after geometry optimisation with CASTEP yielded materials with volume within 3 % and lattice parameters within 1 % relative error with experimental values. The average intercalation potentials calculated with the CASTEP and ONETEP codes are within 3 % agreement with each other.

In this study, we present results of the electronic density of states (DOS) and bulk magnetic moment of iron (Fe), cobalt (Co) and their alloys (FexCo1–x; x = 1.0, 0.95, …, 0.0). Density functional theory with the generalized gradient approximation was applied to obtain geometric and electronic properties. The methodology uses virtual crystal approximation, in conjunction with CASTEP module and the functionals PBE and PBESol of the molecular simulation program Material Studio. We optimized the geometry of the bulk (obtaining their lattice parameters), which the structure was used to determine the bulk magnetic moments. To determine the magnetic moment, we calculated the difference of the electronic DOS of the electrons with spin up and spin down. The geometric optimization and magnetic moment obtained in the present study are very similar to the experimental results, with a maximum error of 8%, which makes the present article interesting.

Previous studies on the preparation of ZnSnO3 under normal pressure and non-epitaxy conditions are ambiguous and contradictory. Therefore, the phase evolution in preparing ZnSnO3 powder with different calcination temperatures was systematically studied by precipitation method under normal pressure in the present work. The phase of the samples was characterized by XRD and Raman spectroscopy. Due to lacking the reliable Raman data of ZnSnO3 in previous literatures, the Raman spectra of ZnSnO3 with LiNbO3-type structure and ilmenite-type structure were simulated by first principle based on CASTEP module of Materials Studio. Moreover, the TG-DSC analysis was carried out for the as-dried precursor powder to further clarify the phase evolution. The results indicated that the phase of the as-dried precursor powder was ZnSn(OH)6 with cubic structure and a series of decomposition reactions occurred with increasing calcination temperature. Wherein, ZnSn(OH)6 began to decompose into ZnSnO3 at about 170 °C, and then ZnSnO3 began to decompose into Zn2SnO4 and SnO2 at about 320 °C. Namely, the thermal stability temperature of ZnSnO3 should be lower than 320 °C under normal pressure. Furthermore, the beginning crystallization temperature for the decomposition-achieved Zn2SnO4 and SnO2 was about 670 °C. In addition, the morphologies of all the samples were detected by SEM, and mainly determined by the crystal structures of the phases in the samples.

Using first-principles calculations, we have investigated the structural, electronic, optical, thermodynamic and vibrational properties of Thorium disulfide (ThS2) in Pnma symmetry. Structural properties are explored using CASTEP simulation code along with Generalized Gradient Approximation. Values of lattice parameters (a = 7.27 A, b = 4.33 A and c = 8.56 A) determined in the present work are found in good agreement with the former studies. After geometry optimization of the crystal structure of ThS2, electronic properties containing the electronic band structure, total density of states and partial density of states have been investigated. ThS2 shows direct energy band gap of 0.995 eV, thus, it belongs to semiconducting materials. Optical analysis discloses that maximum absorption occurs in the UV range of the electromagnetic spectrum. Vibrational properties investigated through density functional perturbation theory depict no imaginary or negative frequencies in the phonon spectrum, leading to its dynamical stability. A low frequency optical mode of vibration showing symmetric stretching has been noticed at 40.53 cm−1 frequency. In order to seek thermo-dynamical stability of thorium disulfide, thermodynamic properties were calculated using harmonic approximation, making thorium disulfide suitable for thermodynamic applications.

In the present work, the structural, magnetic, and theoretical analysis of the Fe–Si alloy prepared by melting and heat-treated was performed. The ordered FeSi simple cubic (sc) phase was obtained by melting and heat treatment processes as determined by X-ray diffraction. The presence of the superstructure peak in the (312) crystalline direction confirms the high structural order reached. Using Mossbauer spectrometry (MS), a paramagnetic behavior with quadrupole splitting of SQ = 0.53 ± 0.02 mm/s was obtained. Although MS indicates paramagnetic behavior, vibrating sample magnetometry (VSM) showed ferromagnetic behavior with a coercive field of 25 Oe, associated with a small amount of Fe3Si segregations detected by scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). Using density functional theory (DFT), the crystalline structures for the simple cubic (sc) Fe50Si50, face-centered cubic (fcc) Fe3Si, and body-centered cubic (bcc) Fe3Si crystalline structures were simulated. Electron total density values were calculated to perform energetic comparisons with magnetic behavior. The electronic structures and magnetic properties of the Fe–Si alloys in different stoichiometric configurations were calculated by CASTEP, which employed first principles DFT. The density of states (DOS) and band structures were calculated together with magnetic properties. The results showed that the high value of the polarization spin for the fcc and bcc structures is due to the contribution of the high amount of Fe atoms above the Si atoms, which is reflected in an increase in the magnetic moment and that their presence could explain the ferromagnetic behavior observed by VSM.

First-principles calculations, with CASTEP code, were employed to study the effect of lithium (Li) and beryllium (Be) doping on structural stability, phase transformation, electronic band structure and optical characteristics of CaTiO3. The substitution of Ca-atoms with the Li- and Be-atoms changes the lattice parameters and hence unit cell volume and consequently the electronic band structure of CaTiO3 is modified. With 12.5% Li- and Be-doping, we observed a structural phase transformation from cubic to pseudo-cubic tetragonal structure which is in good agreement with the literature. The impact of structural phase transformation on the electronic band structure has been explained with the help of total, partial and elemental partial density of states. In case of Li-doping, the value of band gap slightly increases from 1.866 to 1.964 eV while the band gap value decreases to 1.614 eV for Be-doping. In both cases of doping, maxima of valence band are shifted from R to Z symmetry point whereas the minima of conduction band remain at G symmetry point. In pure and doped cases, the nature of the band gap remains unaltered, i.e., indirect band gap. From optical response of the doped compounds, we perceive a red shift in the absorption. With Be- and Li-doping, the static refractive index also increased from 2.48 to 2.63 and 4.1, respectively. The change in electronic structure and optical characteristic with Li- and Be-doping would make this compound a suitable candidate for future optoelectronic devices.

A novel synthesis blend of sodium carboxymethyl cellulose (CMC) with thiobarbituric acid (TBA) [CMC + TBA]B has been doped with CuO to study the optical and direct electrical (DC) properties of [CMC + TBA/CuO]C nanocomposite films. Different characterization techniques for [CMC]TF, [TBA]TF, [CMC + TBA]B and [CMC + TBA/CuO]C such as Fourier-transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and optical properties have been used. SEM showed a good dispersion of copper oxide nanoparticles [CuO]NPs on [CMC + TBA]B film surface. The dielectric constant e(ω), optical conductivity σ(ω) and DC properties increased and demonstrated wave-like performance with increasing [CuO]NPs ratio at hν range of 0.7 eV – 5.0 eV. Copper content [CuO]NPs increases lead to the formation of a wide variety of 3D-semiconductor networks within [CMC + TBA]B film matrix which increase optical conductivity. The optimization was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP). In Experimental section by using Tauc’s equation, the results clearly show that the values of optical energy band gap $$ {E}_g^{Opt} $$ decreases from 2.978 eV for [CMC]TF, 2.725 eV for [TBA]TF, 2.625 eV for [CMC + TBA]B to 2.488 eV for [CMC + TBA/CuO]C. The simulated FTIR, XRD, and optical properties by Gaussian software and CATSTEP are in great agreement with the experimental study. The [CMC + TBA/CuO]C presents a good candidate for optoelectronics and solar cell applications.

Thioborates compounds are receiving increasing attention due to their numerous optical applications. In this work, we present a theoretical prediction of physical properties of CuBS2 and AgBS2 compounds by mean the density functional theory using the pseudo potential plane-wave method implemented in ABINIT and CASTEP codes. We investigated the structure stability and other ground state properties. The dynamical stability is also discussed from the phonon dispersion for the new hypothetical phase. We used the hybrid functional to estimate the band gap. Moreover, we present the optical anisotropy and nonlinear optical properties, both studied compounds have wide band gap, adequate optical birefringence and good second order NLO coefficients, which make them potential candidates for NLO applications.

Effect of anomalous behavior of beryllium (Be) on structural stability, band gap engineering and optoelectronic properties in comparison with magnesium (Mg) doped BaZrO3 perovskite have been explored. All calculations have been performed, by constructing the supercell to overcome the boundary effects, with CASTEP code, established on DFT, by Perdew-Burke-Ernzerhof-Generalized-Gradient-Approximations (PBE-GGA) exchange correlation functional and USP (ultra-soft pseudo-potential). Various properties of the doped and pure compounds are probed such as the analysis of band structure, TDOS (total density of states), PDOS (partial density of states) and their effect on dielectric function. The substitution of Ba-atom with the Mg- and Be-atom change the lattice parameters and modify electronic structure of BaZrO3. In case of Mg and Be doping the value of band gap decreases from 3.119 to 2.844 eV and 0.886 eV. Due to doping of the Mg and Be doping valence band is shifted from R to G symmetry points whereas the conduction band is shifted from G to R symmetry points, with the emergence of new symmetry points, because of Mg- and Be-s-states and showing indirect band gap. From optical properties, a red shift in the absorption edge is noticed for both doped compounds. The static refractive index is also enhanced with Be-doping from of 2.2 to 2.32. The Be and Mg doping in BaZrO3 alters electronic and optical properties emphatically and models this doped material a very prospective contestant for optoelectronic devices.

The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO2 and Ce2O3, at the surface of the films prepared at argon-oxygen flow ratios between 0–7%, whereas the films are completely oxidized into CeO2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25 – 3.1 eV) were derived from the UV-Vis reflectance. A significant change in the band gap was observed as the oxygen pressure was raised from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce2O3 and CeO2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings.

The structures of Si2P2O and Ge2P2O with the space group Cmc21 are derived. The structural, mechanical, elastic anisotropy, electronic and optoelectronic properties are calculated by first principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) at high pressure for Si2P2O and Ge2P2O. By using the elastic stability criteria, it is shown that their structures are all stable. The phonon dispersion spectra are researched throughout the Brillouin zone as implemented in the CASTEP code, which indicates that the optimized structures are stable dynamically. The brittle/ductile behaviors are assessed in the pressures from 0 GPa to 50 GPa. Our calculations present that the performances of them become ductile with pressure rise. Moreover, the anisotropies of them are discussed by the Young's moduli at different pressure, and the results indicate that the anisotropies of them are obvious. The direct band structures of Ge2P2O and the indirect band gap of Si2P2O show that Si2P2O and Ge2P2O present semiconducting character at 0 GPa and 50 GPa. The band structures of Si2P2O are changed obviously with the increase of pressure. The total DOS originate mainly from O ‘s’ states, O ‘p’ states, P ‘s’ states and P ‘p’ states and M ‘p’ states (M=Si, Ge). The trends of DOS for Si2P2O and Ge2P2O display many similarities, and the change of DOS is obviously affected by the pressure for Si2P2O. The optoelectronic properties of them are researched. The calculated static dielectric constants, ɛ1(0), are 3.2 at 0 GPa and 6.4 at 50 GPa for Si2P2O, and the values of Ge2P2O are 10.2 and 9.2 at 0 GPa and 50 GPa.

Perovskite materials possess promising application prospects in photovoltaics and are most likely to replace the dominance of silicon-based solar photovoltaic materials. (K 0.5 Na 0.5 )NbO 3 – x Fe 2 O 3 perovskite ferroelectric ceramics ( x = 0, 0.01, and 0.05) were prepared using a conventional solid-state reaction method. We systematically analyzed the structural, morphological, electric, magnetic, and optical properties. Structural and morphological features of the as-prepared ceramics show that the phases of the materials all are orthorhombic. The appropriate amount of Fe 2 O 3 introduced will improve the electrical properties. Magnetic switching corresponding to a diamagnetic-ferromagnetic transformation was observed. Bandgap ( E g ) modulation was achieved in the Fe 2 O 3 -doped KNN ceramics, with the E g exhibiting a drastic decrease as the doping content increased in experiment where the E g = 2.886, 2.232, and 2.061 eV when x = 0, 0.01, and 0.05, and the CASTEP calculation shows a similar trend, indicating that the materials exhibit a higher performance with the absorption in visible light.

Calculations using the density-functional theory (DFT) in combination with the single defect method were carried out to determine the heat of mixing behaviour of mineral solid solution phases. The accuracy of this method was tested on the halite–sylvite (NaCl–KCl) binary, pyrope–grossular garnets (Mg3Al2Si3O12–Ca3Al2Si3O12), MgO–CaO (halite structure) binary, and on Al/Si ordered alkali feldspars (NaAlSi3O8–KAlSi3O8); as members for coupled substitutions, the diopside–jadeite pyroxenes (CaMgSi2O6–NaAlSi2O6) and diopside–CaTs pyroxenes (CaMgSi2O6–CaAlAlSiO6) were chosen for testing and, as an application, the heat of mixing of the tremolite–glaucophane amphiboles (Ca2Mg5Si8O22(OH)2–Na2Mg3Al2Si8O22(OH)2) was computed. Six of these binaries were selected because of their experimentally well-known thermodynamic mixing behaviours. The comparison of the calculated heat of mixing data with calorimetric data showed good agreement for halite–sylvite, pyrope–grossular, and diopside–jadeite binaries and small differences for the Al/Si ordered alkali feldspar solid solution. In the case of the diopside–CaTs binary, the situation is more complex because CaTs is an endmember with disordered cation distributions. Good agreement with the experimental data could be, however, achieved assuming a reasonable disordered state. The calculated data for the Al/Si ordered alkali feldspars were applied to phase equilibrium calculations, i.e. calculating the Al/Si ordered alkali feldspar solvus. This solvus was then compared to the experimentally determined solvus finding good agreement. The solvus of the MgO–CaO binary was also constructed from DFT-based data and compared to the experimentally determined solvus, and the two were also in good agreement. Another application was the determination of the solvus in tremolite–glaucophane amphiboles (Ca2Mg5Si8O22(OH)2–Na2Mg3Al2Si8O22(OH)2). It was compared to solvi based on coexisting amphiboles found in eclogites and phase equilibrium experiments.

The phase composition, crystal structure and microwave dielectric properties of (1-x) (3ZnO-Nb2O5)-xGeO2 were investigated systematically. The phase composition and phase transformation of (1-x) (3ZnO-Nb2O5)-xGeO2 ceramics were confirmed by XRD refinement, SEM micrographs and EDS analysis. All sintered samples were composed of Zn3Nb2O8 and ZnNb2O6 phases. Phase transition between Zn3Nb2O8 and ZnNb2O6 was closely related the introduction of GeO2. When the doping content was low (x = 0–0.007), the phase transformation from ZnNb2O6 to Zn3Nb2O8 occurred, which was discovered for the first time. To clarify the phase transition, the local charge density and band structures were calculated using the CASTEP program. With the substitution of Ge4+, part of the electrons transferred from the oxygen atom to the middle of 'niobium-oxygen' and 'zinc-oxygen'. According, the covalency of 'niobium-oxygen' and 'zinc-oxygen' was enhanced. The shrinkage of ZnO6 octahedron resulted in a decrease in the coordination number of zinc atoms. At last, the relationships between phase transition, crystal structure and the microwave performance were established. The system of 2.73ZnO-0.91Nb2O5-0.09GeO2 sintered at 1150 °C for 6 h had excellent microwave dielectric properties: er = 21.3, Qf = 99,140 GHz, τf = −54 ppm/°C, which, to our best knowledge, the best performance with relative lower sintering temperature.

In this paper, we have study the structural, elastic, electronic, mechanical, optical and thermodynamic properties of NdPb3 intermetallic compound using density functional theory (DFT) with CASTEP code for the first time. The structural and other physical properties of NdPb3 compared with the results where available and show well accord. The optimized lattice parameters show a good agreement with the experimental data. The elastic constants C i j , bulk modulus B, shear modulus G, Young's modulus Y and Poisson's ratio v are optimized and discussed by using the Voigt-Reuss-Hill (VRH) approximation. The elastic constants show that NdPb3 is a mechanical stable compound. Cauchy pressure, Pugh's ratio and Poisson's ratio indicate that NdPb3 is also a ductile compound associated with ionic bonding nature. Zener's anisotropy index and universal anisotropic index show the anisotropic characteristics of this compound. The density of states (DOS) at Fermi level is high which is mainly contributed by Nd 4f indicates the metallic behavior of this compound. The metallic behavior also characterized by band structure and conductivity. This compound is a good reflector at low energies also have a good quality of absorption at visible region. We also determined the Debye temperature from elastic constants, minimum thermal conductivity, melting temperature sound velocities and D u l o n g − P e t i t l i m i t .

First-principles calculations were performed to explore the structural, elastic and electronic properties of the ternary indium chalcogenides AInQ 2 (A: K, Rb and Q: S, Se, Te) in both monoclinic and triclinic phases. This study is carried out by using the first-principles pseudopotential plane-wave (PP–PW) method as implemented in CASTEP code. Both the generalized gradient approximation of Perdew–Burke–Ernzerhof scheme (GGA–PBE) and the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional were used to treat the exchange-correlation interactions. In order to confirm the previous reports and to understand the effect of symmetry in determining the physical properties of these layered materials we have calculated the structural and the electronic properties at the equilibrium lattice constant for both the systems. The single-crystal elastic constants C i j are calculated using the stress-strain approach. The elastic moduli of the polycrystalline aggregates and their related properties are obtained in the framework of Voigt–Reuss–Hill approximations. Electronic band structure indicates the semiconducting behaviour with a direct band gap at Γ–Γ. The results obtained from the (HSE06) hybrid functional are in excellent agreement with the available experimental data and computed results for the monoclinic and triclinic structures.

Sr2 CeO4 phosphors with different crystalline sizes were synthesized by the sol-gel method or the solid-state reaction. Their crystalline size, luminescence intensity of O2- -Ce4+ charge transfer and energy gaps were obtained through the characterization by X-ray diffraction, photoluminescence spectra, as well as UV-visible diffuse reflectance measurements. An inverse relationship between photoluminescence (PL) spectra and crystalline size was observed when the heating temperature was from 1000°C to 1300°C. In addition, band energy calculated for all samples showed that a reaction temperature of 1200°C for the solid-state method and 1100°C for sol-gel method gave the largest values, which corresponded with the smallest crystalline size. Correlation between PL intensity and crystalline size showed an inverse relationship. Band structure, density of states and partial density of states of the crystal were calculated to analyze the mechanism using the cambrige sequential total energy package (CASTEP) module integrated with Materials Studio software.

As a newly discovered member of the tungstate family, InWO4 hollow nanospheres with a monoclinic wolframite structure were synthesized successfully. The crystal phase of InWO4 was investigated via a combination of CASTEP geometric optimization and experimental simulation. InWO4 has a space group of P2/c with two InWO4 formula units per unit cell. The optimized cell dimensions are a = 5.16 A, b = 5.97 A, and c = 5.23 A, with α = 90°, β = 92.11°, γ = 90°, giving a unit cell volume of 161.10 A3, which is consistent with the experimental measurements. More importantly, InWO4 was a promising host material for different Ln3+ (Ln = Eu and Yb/Er) ions. For InWO4:Yb3+/Er3+ excited at 980 nm, transitions from the 4G11/2 (384 nm), 2H9/2 (411 nm), and 4F7/2 (487 nm) levels to the ground state (4I15/2) of Er3+ were observed. In addition to the aforementioned properties, the InWO4 hollow nanospheres can be used to improve the performance of dye-sensitized solar cells, which is chiefly attributed to theirlight scattering.

Using surface photovoltaic and electric-field-induced surface photovoltaic techniques, as well as a CASTEP simulation method, we have studied the photo-excited and field-induced charge transfer (CT) behaviors of anatase nano-TiO2 particles adsorbed by O2, N2, and water vapor. Our results suggest that the photo-generated carriers transport process is strongly influenced by the adsorbates on the TiO2 nanoparticles. Oxygen molecules enhance the main-band-gap CT transition at 345 nm and inhibit the sub-band-gap CT transition at 419 nm. This can be explained by the 1 π g electrons in adsorbed O2 and the widened bandgap after adsorbing O2. Nitrogen molecules inhibit the main-band-gap and the sub-band-gap CT transitions differently. This can be explained by the 3 σ g and 1 π g electrons of adsorbed N2, which may cause more new surface states in between the bandgap and decrease the valence band edge of nano-TiO2, as suggested by the CASTEP simulation. The influence of adsorbed water molecule on the main-band-gap CT transition is much stronger than that on the sub-band-gap CT transition.

Data presented in this article are related to the research article entitled O2−–V5+ charge transfer band, chemical bond parameters and R/O of Eu3+ doped Ca(VO3)2 and Ca3(VO4)2: A comparable study[ing Li, Yu Pan, Wenjun Wang, Zihao Wen, Xuanxi Leng, Qi Wang, Liqun Zhou, Haibing Xu, Qinghua Xia, Li Liu, Hongping Xian, Xiaoguang Liu]. The data present the fitting results of the broad excitation spectra of Ca(VO3)2:1%Eu and Ca3(VO4)2:1%Eu using the Gaussian model, the O/R values using the experimental PL emission results. The data compares the optimized cell parameters for Ca(VO3)2: 1%Eu and Ca3(VO4)2:1%Eu through the CASTEP geometry optimization with their initial cell parameters.