Wu J.Li Z.Peng L.Zhang J....
5页查看更多>>摘要：? 2021 Elsevier B.V.The zirconium oxynitride (ZrNxOy) thin films were deposited on the SiO2/Si substrate via direct current reactive magnetron sputtering, by tuning the reactive gas ratio r (the volume ratio between 1% O2+99% N2 and Ar) from 5.0% to 20.0%. The temperature dependence of resistivity reveals that the ZrNxOy films for r < 10.0% show the metallic transport behaviors, and the remarkable semiconductor transport features are presented while r > 15.0%. The metal-insulator transition is thus observed in the ZrNxOy films by tuning r. This result provides insight into the design and control of the electrical properties in ZrNxOy-based devices.
原文链接:
NSTL
Elsevier
Mebarkia I.Manallah A.Belghit R.
5页查看更多>>摘要：? 2021 Elsevier B.V.This study deals with the first theoretical investigation of structural, mechanical, electronic, and optical properties of ABrF4 (A = Na, K, and Rb) ternary compounds using ab-initio calculations within the framework of the density functional theory (DFT) using the pseudo-potential plane-wave method. The structural parameters are in agreement with the experimental values stated in the literature. The elastic constants indicate that these compounds are ductile. For a better and in-depth confirming the anisotropic character of the mechanical properties, several indexes such as the universal anisotropic, and the percentage elastic anisotropy for compression and shear have been investigated. The electronic properties indicate that these compounds are wide-band gap semiconductor materials. The optical properties including the dielectric function, the absorption and extinction coefficients, the optical reflectivity and conductivity, the refractive index, and the energy loss function have been studied in detail. The wide optical absorption range in the ultraviolet (UV) region suggests that these materials could be useful for specific implementations in UV optoelectronic devices; therefore, this theoretical investigation is probable to motivate future experimental works.
原文链接:- NSTL
- Elsevier
Bessadok M.N.Ahmed W.El Mir L.Bouzidi C....
5页查看更多>>摘要：? 2021 Elsevier B.V.Nanocomposite based on α-Zn2SiO4:Ca nanoparticles embedded in silica matrix was synthetized by sol-gel method followed by thermal treatment at high temperature. The structural, morphological and optical properties were investigated. XRD analysis presents weak willemite peaks at 600 °C which has become clearer at 1200 °C with a grain size of about 60 nm. Optical analysis reveals a decrement in bandgap value from 5.44 eV to 5.24 eV after the incorporation of calcium ions (Ca2+). The PL spectrum presents two emission bands in red region. The most intense one appears at 735 nm and can be attributed to Non Bridging Oxygen Hole Center (NBOH) emission while the second, located at 685 nm, is attributed to silanol group Si–OH. The obtained results prove that, the incorporation of calcium in the nanocomposite enhance the creation of very active deep centers promising for many advanced technological applications.
原文链接:- NSTL
- Elsevier
Vignesh R.Prabha C.N.Sivakumar R.Sanjeeviraja C....
5页查看更多>>摘要：? 2021 Elsevier B.V.In this work, we report on the diverse optical parameters of Mn2O3 thin films prepared by nebulized spray pyrolysis technique by the effect of spray solution concentration. X-ray diffraction study confirmed the Mn2O3 films belong to cubic structure. The Raman vibrational band observed at 636 cm?1 is related with the symmetric stretching of Mn–O bond of trivalent manganese ions (Mn3+). The surface morphological study showed that the nano-sized particles are homogenously distributed on the film surface. The films exhibit the highest transmittance in the near infrared region. The spray solution concentration induced reduction of Urbach energy (from 677 to 655 meV) indicates the decrease in degree of crystal defects in the film. The extinction coefficient of the film was obtained in the order of 10?2. It was observed that the optical dispersion threshold point (TODT) of Mn2O3 thin film is coincides with the refractive index threshold wavelength (λrtw) of the material. This was further corroborated from the intersection of phase velocity and group velocity curves at the point of λrtw or TODT. This indicates that no optical dispersion was taken place at that point and therefore the phase velocity is equal to the group velocity. The possible correlations among the data were made with the light of underlying concepts.
原文链接:- NSTL
- Elsevier
Dwij V.De B.K.Sharma G.Shukla D.K....
5页查看更多>>摘要：? 2021 Elsevier B.V.BaTiO3 is a classical ferroelectric studied for last one century for its ferroelectric properties. Lattice dynamics of BaTiO3 is crucial as the utility of devices is governed by phonons. In this work, we show that traditional characterization of the polar phonon modes is ambiguous and often misinterpreted. By combining Raman, Neutron and X-ray diffraction, dielectric spectroscopic observations with first principle calculations, we have re-examined the character of the normal modes of phonons of tetragonal BaTiO3. We obtained Eigen displacements of vibrational modes through DFT calculations and reclassified the polar modes being Slater (Ti–O), Last (Ba–TiO3) and Axe (BO6) vibrations by correlating experimental and theoretical calculations. The study thus provides authentic nomenclature of the polar modes.
原文链接:- NSTL
- Elsevier
