Yu, RichengJi, YuWang, WeipengDing, Yifan...
6页查看更多>>摘要：A transition metal oxide, NbMoO4, is synthesized by using a solid-state reaction method, then the morphology of the sample is characterized by the scanning electron microscopy. The X-ray diffraction refinement and transmission electron microscopy results show that the sample has a TiO2 rutile-type structure with space group P4(2)/mnm, which is the high-temperature phase of NbO(2 )and MoO2. Our transport result indicates that the resistivity is as low as 0.02 Omega.cm in the temperature range from 2 to 300 K, indicating the metallicity of NbMoO4. Furthermore, the calculated density of states and experimental specific heat data from 2 to 20 K also confirm the metallic behavior. Our magnetization experiments indicate that the NbMoO4 exhibits paramagnetism. The valence states of Nb4+ and Mo4+ in NbMoO4 are revealed by the X-ray absorption spectroscopy.
原文链接:
NSTL
Elsevier
Dhiman, VikasKondal, Neha
13页查看更多>>摘要：ZnO is a large-band-gap semiconductor with promising photocatalytic properties. The high bandgap (E-gap) of ZnO, on the other hand, restricts its application in solar-driven photocatalysis since it can only respond to UV light that makes up just 5% of the full solar spectrum. Apart from this, it also suffers from the problem of fast charge recombination. During the last few years, great attention has been paid to increase the efficiency of ZnO in solar-driven photocatalysis, by increasing light-harvesting span or charge separation efficiency. It has been reported that when ZnO is coupled with MoS2 (Low E-gap semiconductor), its light-harvesting span extends to most of the solar spectrum due to the synergic adsorption of two dissimilar E-gap semiconductors. Furthermore, MoS2-ZnO nanocomposites also show decreased charge recombination and fast interfacial charge transfer. In this article, we have reviewed the wide solar applications of MoS2-ZnO nanocomposites and the mechanisms of these photo-induced reactions.
原文链接:- NSTL
- Elsevier
Pandey, AnandKumar, Lokendra
7页查看更多>>摘要：Strain management in organometal halide perovskite materials is one of the important strategies to improve charge transport, ion migration and crystallinity of these materials. This work reveals the internal relationship between the perovskite processing temperature and the optoelectronics properties of MAPbI(3-x)Cl(x) perovskite films. The MAPbI(3-x)Cl(x) films have fabricated on various temperature ranges from 80 ?degrees C to 180 ?degrees C using hot casting technique and explored their structural, surface morphological, optical, and electrical properties. Lattice strain has observed and found to be reduced on increasing the processing temperature and at a particular processing temperature, perovskite films exhibit free of strain. Urbach energy and trap levels have significantly reduced at higher temperatures which confirm the superior optoelectronic feature of perovskite semiconductors. Further, Schottky diodes with device configuration FTO/MAPbI(3-x)Cl(x)(/Ag)& nbsp;were fabricated and ideality factor, barrier height and reverse saturation current density have been determined in order to explore the charge transport properties of the films.
原文链接:- NSTL
- Elsevier
Chidhambaram, N.Kumari, S. SenthilNirmala, W.Gobalakrishnan, S....
11页查看更多>>摘要：An insightful study intended to comprehend the integrative impact of tin and graphene on the physical features of ZnO-Sn@Graphene nanopowders communicated herein. A facile in situ wet chemical approach was utilized to synthesize ZnO-Sn@Graphene. Their microstructure, morphological, and optical properties were explored by employing analytical techniques such as x-ray diffraction, scanning and tunneling electron microscopy, UV-Vis diffused reflectance, and photoluminescence spectroscopy. The influence of tin and graphene inclusion on the ZnO-Sn@Graphene was compared with the counterparts ZnO-Sn and ZnO. The ZnO-Sn@Graphene nano-powders revealed the lowest crystallite size value of 28 nm indicating the in situ synthesis strategy restricts the growth of nanoparticles on the graphene sheets. Morphological investigations depicted the graphene sheets keeping the semiconductor nanoparticles dispersed form. The amalgamation of ZnO-Sn with graphene leads to a significant reduction in the optical bandgap value of 3.20 eV. The ZnO-Sn@Graphene nanopowders disclosed an efficient photogenerated charge carriers separation and photoluminescence quenching.
原文链接:- NSTL
- Elsevier
Nikoghosyan, H. S.Nikoghosyan, G.
7页查看更多>>摘要：A theoretical study of the spectrum of quasiparticles in a superlattice of spherical quantum dots (QDs) with a trapezoidal potential profile with a weak coupling of quasiparticles between QD layers is carried out. The calculations were performed using the example of spherical QDs InGaAs embedded in GaAs in the form of a superlattice. The model of the trapezoidal QD profile with three variable parameters is especially suitable for considering such zero-dimensional structures when, due to the different lattice constants of the QD material and the matrix medium, the boundary between them is fuzzy and is modeled by a certain transition region. The dependences of the energies of the underlying bands on the geometric parameters of the superlattice are investigated, which can be used to determine the metric of zero-dimensional structures by comparing it with the experimental intraband absorption spectra. The sensitivity of the position of the bands to changes in the parameters of the potential profile is revealed, which makes it possible to efficiently analyze the tunneling passage of carriers between QDs, to study the processes of controlled relaxation of carriers in QDs, which is important for the operation of lasers based on zero-dimensional structures with mismatched lattice constants of the QD material and the matrix medium.
原文链接:- NSTL
- Elsevier
Wang, DongmeiLeng, ZhuangJiang, XiliangWang, Xinyu...
6页查看更多>>摘要：This paper reports a series of Cr4+: LiInGeO4, based on a high-temperature solid-phase synthesis method and the effect of LiInGeO4-doped Cr4+ ions on the spectral properties and luminescence colors in the near-infrared re-gion. Under 808 nm excitation, the emission spectra showed a broad band at 1000-1500 nm, with a maximum peak occurring at 1218 nm due to the T-3(2)& RARR;(3)A(2) transition of Cr4+ ions. The lifetime decreases with the increasing amount of Cr4+ ions, from 8.30035 mu s to 6.656 mu s. The chromium's chemical composition and valence state in LiInGeO4 were analyzed by x-ray photoelectron spectroscopy. The results showed that the chromium in LiInGeO4 was tetravalent, and no trivalent chromium was found. The results show that LiInGeO4 crystals can have promising applicability in anti-counterfeiting due to the possibility of both up-conversion and down-conversion glowing.
原文链接:- NSTL
- Elsevier
Dantelle, GeraldineReita, ValerieIbanez, AlainLedoux, Gilles...
6页查看更多>>摘要：Y3Al5O12 (YAG) nanocrystals codoped with Nd3+ and Cr3+ ions have been produced by a modified solvothermal method. The incorporation of both Nd3+ and Cr3+ inside the YAG network has been attested by X-ray diffraction and photoluminescence measurements. Modification of the excitation wavelength leads to ratiometric intensity changes between the luminescence attributed to Nd3+ and that of Cr3+. Temperature-dependent luminescence spectra have been analyzed according to the different excitation wavelengths. The highest relative thermal intensity (S-r = 2.5%.K-1) is obtained under a 532 nm excitation, which favors the direct and independent excitation of Cr3+ and Nd3+.
原文链接:- NSTL
- Elsevier
Dakhlaoui, HassenAl-Shameri, Najla S.
6页查看更多>>摘要：In this paper, we have discussed theoretically the effect of an applied bias voltage and the temperature on the spin-tunneling time, spin-dependent polarization and current densities of holes in GaAs/GaMnAs double barriers using the transfer matrix method (TMM). The behavior of the transmission coefficients for different spin ori-entations (up and down), various applied voltages and different temperatures were calculated. Our findings indicate that the maxima of the spin-up transmission coefficient shift towards the lower energies by increasing the applied bias voltage. Furthermore, our structure is almost transparent for spin-down holes and presents some resonances for spin-up ones. In addition, we have found that the tunneling time decreases progressively by enhancing the applied voltage. It is also shown that the current densities of holes with both spin-up and down orientations present a negative differential resistance (NDR). This (NDR) resistance is more intense for spin-up holes than spin-down ones. Consequently, the obtained results pointed out that we can design and fabricate a high-speed spin-filters and diodes by fixing the appropriate values of applied voltages and temperatures.
原文链接:- NSTL
- Elsevier
