Ab initio Investigation of the structure and electronic properties of normal spinel Fe2SiO4

Transition metal spinel oxides have recently been predicted to create efficient transparent conducting oxides for optoelectronic devices. These compounds can be easily tuned by doping or defect to adapt their electronic or magnetic properties. However, their cation distribution is very complex and band structures are still subject to controversy. We propose a complete density functional theory investigation of fayalite (Fe2SiO4) spinel, using Generalized Gradient Approximation (GGA) and Local Density Approximation (LDA) in order to explain the electronic and structural properties of this material. A detailed study of their crystal structure and electronic structure is given and compared with experimental data. The lattice parameters calculated are in agreement with the lattice obtained experimentally. The band structure of Fe2SiO4 spinel without Coulomb parameter U shows that the bands close to Fermi energy appear to be a band metal, with four iron d-bands crossing the Fermi level, in spite of the fact that from the experiment it is found to be an insulator

Structural stabilities, electronic structure, optical and elastic properties of ternary Fe2SiO4 spinel: An ab initio study

Spinel-type Fe2SiO4 has been one of the materials receiving much attention in the field of new spintronics and optoelectronics materials, due to its promising physical properties of high transparency achieved experimentally. In this research, we systematically investigate the structural stabilities, elastic, optical and magnetic, properties of Fe2SiO4 spinel using the first-principles theory within generalized gradient approximation (GGA) and GGA + U frameworks. With the GGA + U method, Fe2SiO4 is shown to be stable for both spin-up and down calculations. Furthermore, incorporating the Hubbard correction parameter due to the localized Fe-3d electrons produced the bandgap value to be close to available experimental data. Our result reveals additional information on Fe2SiO4 spinel which is useful for molecular magnet and spintronics devices

First-principles calculations of structural, electronic, and optical properties for Ni-doped Sb2S3

Antimony sulphide (Sb2S3) is a potential candidate for alternative material in solar cell application. The structural, electronic, and optical properties of Ni doped Sb2S3 were calculated using full potential linear augmented plane wave (FP-LAPW) based on popular density-functional theory (DFT). The equilibrium lattice parameters have been calculated using Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (PBE-GGA). The band structure and density of state for Ni-doped Sb2S3 have been determined using Tran Blaha modified Becke-Johnson (TB-mBJ) potential. Our results indicate that Ni doped Sb2S3 has lower band gap energy compare to pure-Sb2S3. The optical properties of Ni-doped Sb2S3 such as absorption coefficient, reflectivity, refractive index, energy-loss function and extinction coefficient are presented. The results demonstrate that Ni-doped Sb2S3 has higher optical absorption coefficient in the visible region than pure-Sb2S3 which is good for optoelectronic applications

First-principles investigation of structural, elastic, electronic and thermodynamic properties of strongly correlated ternary system: The DFT plus U approach

The elastic, thermodynamic and electronic properties of rhombohedra SiFe2O4 spinel-type are investigated using generalized gradient approximation (GGA) and local density approximation (LDA) approach. The results obtained confirmed the failure of bare DFT to produce the fundamental bandgap of strongly correlated systems. By incorporating the Hubbard correction term (U) on Fe 3d electron, the calculated bandgap using GGA + U was found to be 3.86 eV and this value is comparable with experimental data. The Pugh's ratio and Cauchy pressure values demonstrate the ductility nature of SiFe2O4 spinel. The temperature variation with thermodynamic properties descript the stability of SiFe2O4 spinel. The heat capacity at constant volume increases sharply with temperature and tends to the Dulong-Petit limit at high temperature. The reported value of the bandgap lies within near-ultraviolet (UV) wavelength, revealing that SiFe(2)O(4)spinel-type material may be useful for the photo electrochemical cell of water splitting, flat-panel displays and other optoelectronic applications

Effects of irradiation time on the structural, elastic, and optical properties of hexagonal (wurtzite) zinc oxide nanoparticle synthesised via microwave-assisted hydrothermal route

Zinc oxide (ZnO) is a vital nanomaterial highly valued in electronics and optoelectronics due to its remarkable multifunctional properties. This study prepared ZnO nanoparticles using a simple hydrothermal microwave process. The influence of irradiation time on the structural, elastic and optical properties of the ZnO nanoparticles was investigated. X-ray diffraction (XRD) analysis confirmed the hexagonal (wurtzite) structure of the ZnO nanoparticles. In addition, various XRD profile analysis techniques were used in this study, including Scherer method, strain size plot method, Halder–Wagner method, Monshi–Scherer method, and Williamson–Hall method consisting of a uniform deformation model, a uniform stress density model and a uniform deformation energy density model. The estimated mean crystallite size was found to be at 43.53–56.08 nm. Furthermore, atomic force microscopy and transmission electron microscopy were used to investigate the average particle size of the ZnO nanoparticles at different irradiation times. The results were consistent with the mean crystallite size calculated using the X-ray diffraction peak profile analysis techniques. Furthermore, a decrease in the energy band gap estimated by diffuse reflectance spectroscopy was observed, transitioning from 3.32s to 3.29 eV with increasing irradiation time. This observation was confirmed by the distinct and unique ultraviolet photoluminescence emission peaks of the synthesized ZnO nanoparticles, supporting the results of the diffuse reflectance analysis. Based on the presented results, it can be concluded that the X-ray diffraction peak profiling technique is a practical approach for determining the average crystallite size of ZnO nanoparticles prepared using the microwave hydrothermal technique and that it can be used for size-dependent applications