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Fabrication,microstructure,and optical properties of nanocrystalline transparent LAST glass ceramics containing CeO_2

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International Journal of Minerals,Metallurgy and Materials 2014年第4期21卷 401-407页

作者： Mohammad Sadegh Shakeri Materials and Energy Research Center (MERC)

In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.

关键词： glass ceramics nanocrystals alurninosilicates titanates transparency optical properties

First-principles study of the electronic and optical properties of ZnO nanowires

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Chinese Physics B 2009年第6期18卷 2508-2513页

作者：张富春张志勇张威虎阎军峰贠江妮 Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences College of Physics & Electronic Information Yan’an University Information Science and Technology Institution Northwest University

The geometric, energetic, electronic structures and optical properties of ZnO nanowires （NWs） with hexagonal cross sections are investigated by using the first-principles calculation of plane wave ultra-soft pseudo-potential technology based on the density functional theory （DFT）. The calculated results reveal that the initial Zn-O double layers merge into single layers after structural relaxations, the band gap and binding energies decrease with the increase of the ZnO nanowire size. Those properties show great dimension and size dependence. It is also found that the dielectric functions of ZnO NWs have different peaks with respect to light polarization, and the peaks of ZnO NWs exhibit a significant blueshift in comparison with those of bulk ZnO. Our results gives some reference to the thorough understanding of optical properties of ZnO, and also enables more precise monitoring and controlling during the growth of ZnO materials to be possible.

关键词： density functional theory ZnO nanowires electronic structure optical properties

Electronic structure and optical properties of LiXH_3 and XLiH_3 (X = Be, B or C)

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Chinese Physics B 2008年第6期17卷 2222-2228页

作者：伞晓娇何志马琰铭崔田刘冰冰邹广田 National Laboratory of Superhard Materials Jilin University

The equilibrium lattice constant, the cohesive energy and the electronic properties of light metal hydrides LiXH3 and XLiH3 （X = Be, B or C） with perovskite lattice structures have been investigated by using the pseudopotential plane-wave method. Large energy gap of LiBeH3 indicates that it is insulating, but other investigated hydrides are metallic. The pressure-induced metallization of LiBeH3 is found at about 120 GPa, which is attributed to the increase of Be-p electrons with pressure. The electronegativity of the p electrons of X atom is responsible for the metallicity of the investigated LiXH3 hydrides, but the electronegativity of the s electrons of X atom plays an important role in the metallicity of the investigated XLiH3 hydrides. In order to deeply understand the investigated hydrides, their optical properties have also been investigated. The optical absorption of either LiBeH3 or BeLiH3 has a strong peak at about 5 eV, showing that their optical responses are qualitatively similar. It is also found that the optical responses of other investigated hydrides are stronger than those of LiBeH3 and BeLiH3 in lower energy ranges, especially in the case of CLiH3.

关键词： plane-wave method metal hydrides electronic structure optical properties

Influences of anionic and cationic dopants on the morphology and optical properties of PbS nanostructures

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Chinese Physics B 2014年第10期23卷 566-572页

作者： Ramin Yousefi Mohsen Cheragizade Farid Jamali-Sheini M. R. Mahmoudian Abdolhossein Saaédi Nay Ming Huang Depertment of Physics Masjed-Soleiman Branch Islamic Azad University (I.A.U.) Masjed-Soleiman Iran Department of Electrical Engineering Bushehr Branch Islamic Azad University (I.A.U.) Bushehr Iran Department of Physics Ahwaz Branch Islamic Azad University Ahwaz Iran Department of Chemistry Shahid Sherafat University of Farhangian 15916 Tehran Iran Low Dimensional Materials Research Center Department of Physics Faculty of Science University of Malaya 50603 Kuala Lumpur Malaysia

Selenium and zinc are used as anionic and cationic dopant elements to dope PbS nanostructures. The undoped and doped PbS nanostructures are grown using a thermal evaporation method. Scanning electron microscopy （SEM） results show similar morphologies for the undoped and doped PbS nanostructures. X-ray diffraction （XRD） patterns of three sets of the nanostructures indicate that these nanostructures each have a PbS structure with a cubic phase. Evidence of dopant incorporation is demonstrated by X-ray photoelectron spectroscopy （XPS）. Raman spectra of the synthesized samples con- firm the XRD results and indicate five Raman active modes, which relate to the PbS cubic phase for all the nanostructures. Room temperature photoluminescence （PL） and UV-Vis spectrometers are used to study optical properties of the undoped and doped PbS nanostructures. optical characterization shows that emission and absorption peaks are in the infrared （IR） region of the electromagnetic spectrum for all PbS nanostructures. In addition, the optical studies of the doped PbS nanos- tructures reveal that the band gap of the Se-doped PbS is smaller, and the band gap of the Zn-doped PbS is bigger than the band gap of the undoped PbS nanostructures.

关键词： PbS nanostructures anionic dopant cationic dopant thermal evaporation optical properties

Electronic and optical properties of O-Terminated Armchair Graphene Nanoribbons

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Chinese Journal of Chemical Physics 2016年第2期29卷 205-211,I0001页

作者：鲁道邦罗长更宋玉玲潘群娜濮春英南阳师范学院物理与电子工程学院南阳473061 南阳师范学院计算机与信息技术学院南阳473061

The structure, electromagnetic and optical properties of the O-terminated graphene nanorib- bons with armchair edge are studied using first-principles theory. The results show that the O-terminated armchair edge are more stable than the H-terminated ribbons and show metal- lic character. Spin-polarized calculations reveal that the antiferromagnetic state are more stable than the ferromagnetic state. The energy band and density of states analyses show that the O-terminated armchair edge are antiferromagnetic semiconductors. Because of the terminated 0 atoms, the dielectric function has an evident red shift and the first peak is the strongest with its main contribution derived from the highest valence band. The peaks of the dielectric function, reflection, absorption, energy loss are related to the transition of electrons. Our results suggest that the O-terminated graphene nanoribbons have potential applications in nanoelectronics, opto-electric devices.

关键词： First-principles Electronic properties optical properties O termination Graphene nanoribbons

Band structure,Fermi surface,elastic,thermodynamic,and optical properties of AlZr3,AlCu3,and AlCu2Zr:First-principles study

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Chinese Physics B 2016年第8期25卷 103-112页

作者： Parvin R Parvin F Ali M S Islam A K M A Department of Physics Rajshahi University Rajshahi-6205 Bangladesh Department of Physics Pabna University of Science and Technology Pabna 6600 Bangladesh International Islamic University Chittagong 154/A College Road Chittagong-4203 Bangladesh

The electronic properties（Fermi surface,band structure,and density of states（DOS）） of Al-based alloys AlM3（M=Zr and Cu） and AlCu2Zr are investigated using the first-principles pseudopotential plane wave method within the generalized gradient approximation（GGA）.The structural parameters and elastic constants are evaluated and compared with other available ***,the pressure dependences of mechanical properties of the compounds are *** temperature dependence of adiabatic bulk modulus,Debye temperature,specific heat,thermal expansion coefficient,entropy,and internal energy are all obtained for the first time through quasi-harmonic Debye model with phononic effects for T = 0 K-100 *** parameters of optical properties（dielectric functions,refractive index,extinction coefficient,absorption spectrum,conductivity,energy-loss spectrum,and reflectivity） of the compounds are calculated and discussed for the first *** reflectivities of the materials are quite high in the IR-visible-UV region up to ~ 15 eV,showing that they promise to be good coating materials to avoid solar *** of the properties are also compared with those of the Al-based Ni3 Al compound.

关键词： first principle calculations Fermi surface elastic moduli entropy and internal energy optical properties

Electronic and optical properties of the zinc-blende structured LiZnN under pressure

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Chinese Physics B 2009年第7期18卷 2938-2944页

作者：常景兰俊卿艾琼陈向荣 School of Physical Science and Technology Sichuan University

The electronic and optical properties of the cubic zinc-blende （ZB） structured filled tetrahedral semiconductor α-LiZnN under pressure are investigated by using ab initio plane wave pseudopotential density functional theory method within the generalized gradient approximation （GGA）.The electronic band structure and the density of state under pressure are systematically *** basic optical constants,including the reflection and absorption spectra,the energy-loss function,the complex refractive index and the dielectric function,are calculated and analysed at different external *** results suggested that the ZB α-LiZnN is transparent in the partially ultra-violet to the visible light region,and it seems that the transparency is hardly affected by the pressure.

关键词： density functional theory electronic structure optical properties LiZnN

Influence of Te doping on the dielectric and optical properties of InBi crystals grown by directional freezing

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International Journal of Minerals,Metallurgy and Materials 2014年第5期21卷 503-509页

作者： C.J. Ajayakumar A.G. Kunjomana Crystal Research Centre Department of PhysicsChrist University

Stoichiometric pure and tellurium （Te） doped indium bismuthide （InBi） were grown using the directional freezing technique in a fabricated furnace. The X-ray diffraction profiles identified the crystallinity and phase composition. The surface topographical features were observed by scanning electron microscopy and atomic force microscopy. The energy dispersive analysis by X-rays was performed to identify the atomic proportion of elements. Studies on the temperature dependence of dielectric constant （e）, loss tangent （tan6）, and AC conductivity （cry） reveal the existence of a ferroelectric phase transition in the doped material at 403 K. When InBi is doped with tellurium （4.04 at%）, a band gap of 0.20 eV can be achieved, and this is confirmed using Fourier transform infrared studies. The results thus show the conversion of semimetallic InBi to a semiconductor with the optical properties suitable for use in infrared detectors.

关键词： crystals indium bismuthide tellurium doping optical properties dielectric properties phase transitions

Theory, simulation and experiment of optical properties of cobalt ferrite(CoFe2O4) nanoparticles

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Journal of Materials Science & Technology 2020年第22期54卷 180-187页

作者： Elham Gharibshahi Brandon D.Young Amar S.Bhalla Ruyan Guo Department of Electrical and Computer Engineering University of Texas at San Antonio.One UTSA CircleSan AntonioTX 78249USA

optical properties of cobalt ferrite(CoFe2O4) nanoparticles are modeled and simulated employing finite element analysis(FEA) and density functional theory(DFT) for different particle sizes. The simulated absorption maxima of electronic excitations is red-shifted from 330 nm to 410 nm using finite element analysis and from 331.27 nm to 409.07 nm using quantum mechanical method, with increasing particle sizes from 40 nm to 50 nm. The measured absorption maxima matched the simulated results reasonably well and red-shifted to longer wavelengths from 315.59 nm to 426.73 nm with the increase in particle sizes from 30 nm to 50 nm. The DFT simulated, FEA simulated and experimentally derived optical band gap energies, Eg, were also acquired and compared. The simulated Egvalues decreased from 3.228 to 2.478 e V and from 3.266 to 2.456 e V, while the experimental Egvalue decreased from 3.473 to 2.697 e V, with increasing the particle sizes. The research demonstrated that the optical absorption of CoFe2O4 nanoparticles can be described with high accuracy using the quantum mechanical interpretation based on DFT. FEA based simulations have shown limitations for smaller(optical absorption properties and optical band edges, and thus contribute to understanding and design of CoFe2O4 nanoparticle properties prior to fabrication and functionalization of them, for a wide range of applications especially for sensing and photonic wave modulations.

关键词： Cobalt ferrite(CoFe2O4)nanoparticles optical properties Band gap energy DFT simulation of nanoparticles COMSOL simulation of nanoparticles