Deshmukh, Akash A.Khond, Anuj A.Bhatt, Jatin G.Palikundwar, Umesh A....
9页查看更多>>摘要：This work has investigated the formation of the local structure order around Ni in Hf-Cu-Ni glassy ribbons by employing X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy at Ni K-edge. XANES probed 1s to 4p transition at the shoulder of the spectra. The main peak of the spectra corresponds to the 1s to 4p dipole selection rule. The magnitude of the first peak of the EXAFS signal, belonging to the first coordination shell of Ni, decreased with an increase in Ni concentration. The coordination number (CN) of Ni/Cu atoms increases, whereas that of Hf atoms decreases with increasing Ni concentration. The first peak of Hf57Cu11Ni32 (Hf-57), Hf59Cu18Ni23 (Hf-59), and Hf60Cu21Ni19 (Hf-60) is dominated by Ni-Ni and Ni-Cu pair. A nearly linear decrease in atomic distances of Ni-Hf pair is observed with an increase in CN of Ni/Cu, thereby indicating atomic re-arrangement around the central absorbing atom. Hf-57 with large CN of Ni/Cu atoms has shown the most negative P-HS (product of enthalpy of chemical mixing and normalized mismatch entropy) and large supercooled liquid region. This work reflects that the CN of an element strongly influences the glass formation ability of an alloy.
原文链接:
NSTL
Elsevier
Sukharom, SiwakornBoonchun, AdisakReunchan, PakpoomJungthawan, Sirichok...
7页查看更多>>摘要：Understanding of materials at atomic scale is mandatory for improving their physical properties in the desired way. Here, first-principles calculations with the most accurate hybrid functional are performed to investigate one of the most attractive photocatalyst ZnIn2S4. The electronic structures of perfect and defective cubic-ZnIn2S4 are examined as a representative of other ZnIn2S4 polymorphs. The influence of growth conditions on the photocatalytic activity of ZnIn2S4 is elucidated by considering the formation energy of native point defects under different growth conditions. Our results reveal that undoped ZnIn2S4 is a native n-type material owning to the high pinned Fermi-level under all growth conditions. The source of electron carriers in undoped ZnIn2S4 is the In-Zn antisite defect and its photocatalytic performance is declined by the formation of dominant compensating Zn vacancy defect. The S-poor growth coyndition of undoped ZnIn2S4 is unveiled to provide the best photocatalytic performance due to the highest pinned Fermi-level.
原文链接:- NSTL
- Elsevier
El-Zahhar, Adel A.Ashraf, I. M.Idris, Abubakr M.Zkria, Abdelrahman...
7页查看更多>>摘要：Composite films of polyvinyl alcohol/lead iodide (PVA/PbI2) were prepared with different concentrations of PbI2 using low-cost casting process. The characteristics of the prepared films were analyzed by XRD and SEM. The XRD results showed increased crystalline nature with PbI2 content and the SEM micrographs revealed homogeneous particles distribution of PbI2 within the polymer. The optical parameters of PVA/PbI2 films were measured through UV-Vis absorption-transmittance spectroscopy. The indirect energy gap for PVA was found to be 4.75 eV, while the PVA/PbI2 film with 10 wt% PbI2 showed direct transition of 2.47 eV and indirect transition of 2.15 eV. The PVA film resistivity was found to be 1.79 x 10(9) Omega cm in the dark and decreased to1.85 x 10(8) Omega cm at 7000 lux. The film resistivity was found to decrease as the PbI2 content ratio increased up to 10 wt%. The results also showed gradual increase in photo sensitivity with increasing PbI2 content ratio in the composite films. The optical properties revealed that the composite films (PVA/PbI2) could be used in different optoelectronic applications.
原文链接:- NSTL
- Elsevier
Juthy, Z. K.Pikul, M. A. J.Akanda, M. A. S.Islam, M. T....
6页查看更多>>摘要：We investigate the shape anisotropy effect on the magnetization reversal of a nanoparticle driven by a down-chirp microwave field pulse (DCMP). Based on the Landau-Lifshitz-Gilbert equation, numerical results reveal that the microwave amplitude, initial frequency, and chirp rate of DCMP decrease with the increase of shape anisotropy. For a certain shape of the nanoparticle, the reversal time is significantly reduced. These findings can be attributed as the shape anisotropy opposes the magnetocrystalline anisotropy, and thus the energy barrier decreases. The result of damping dependence of reversal indicates that there exists an optimal damping situation at which magnetization is fastest. Moreover, the required microwave field amplitude can be lowered by applying the spin-polarized current simultaneously. The usage of an optimum combination of DCMP and current is suggested to achieve cost-effective and faster switching. So these findings might be useful to realize the fast and power-efficient data storage device.
原文链接:- NSTL
- Elsevier
Dong, YihangSun, XiaomingLiu, ZhaoyangQiu, Guoxing...
5页查看更多>>摘要：In this paper, (CuO)(x)(8YSZ)(1-x) (0 <= x <= 0.3) is prepared by using a co-precipitation method. Its electrical conductivity increases to a maximum at (CuO)(0.1)(8YSZ)(0.9), and then decreases with increasing CuO doping content. An oxygen sensor is fabricated by Pt paste method based on 8YSZ (8 mol% Y2O3 stabilized ZrO2) solid electrolyte and (CuO)(0.1)(8YSZ)(0.9) dense diffusion barrier for the first time. A limiting current of the sensor is reached under different conditions, such as temperature (T) of 720-870 degrees C, oxygen concentration (x(O-2)) of 0-4%, carbon dioxide concentration (x(CO2)) of 0-100%, water vapor pressure (p(H2O)) of 280.66-2268.63 Pa, and testing time of 120 h. The oxygen sensor exhibits excellent sensing performances, its single selectivity to oxygen and resistance to interference from other gases. Moreover, the performances of the oxygen sensor do not decay and remain well under long-term high temperature operation.
原文链接:- NSTL
- Elsevier
Anversa, JonasRupp, Caroline JaskulskiPiquini, Paulo Cesar
7页查看更多>>摘要：The robustness of the Dirac-like states in topological insulators depends on the preservation of the time-reversal symmetry. A magnetic impurity can locally break this symmetry and destroy the protected edge states. However, it is not clear how the influence of this symmetry breaking field depends on the distance between the edge structures (surface or interface) and the magnetic impurity. In this work we use the density functional theory to study the properties of the HgTe/CdTe (001) interface and the (001) HgTe surface in the presence of a Fe impurity. Our results show that for a Fe impurity in the HgTe/CdTe, the spin polarization in the edge states decreases due to the coupling between the magnetic moment of impurity and the magnetic moment of heterostructure, inducing an out-of-plane spin polarization at the interface or surface.
原文链接:- NSTL
- Elsevier
Sonmez, F.Ardali, S.Arpapay, B.Tiras, E....
8页查看更多>>摘要：The photoluminescence (PL) properties of InGaN/GaN multiple quantum wells (MQWs) samples with a different quantum well number (two, three, and four) grown by molecular beam epitaxy have been studied in the temperature range between 3 and 300 K. The redshift-blueshift-redshift in the PL peak energy of InGaN well, which is known that as S-shaped behavior, is observed with increasing temperature in the investigated samples. S-shaped behavior is associated with carrier localization states and inhomogeneity in InGaN/GaN MQWs samples. This behavior is explained with the theoretical band tail model. The parameters showing the effect of carrier localization degree are determined and discussed in detail. Furthermore, it is presented the activation energy of charge carriers by using InGaN related-normalized PL peak intensity as a function of the reverse of temperature and Arrhenius function for all samples. The highest PL intensity is obtained in sample B with 3-QWs. Determining carrier localization effect and activation energy plays a vital role in luminescence efficiency and quality of InGaN/GaN MQWs devices.
原文链接:- NSTL
- Elsevier
Sahare, PriyankaSahoo, Bijay Kumar
4页查看更多>>摘要：At optical frequency range, lattice vibrations in piezoelectric crystal are associated with ionic polarizations. A relationship is formulated, based on classical dispersion theory, involving the dielectric constant (epsilon(jj)) and the piezoelectric coefficient (d(jj)) of wurtzite GaN. The relation is utilized to investigate the piezoelectric lattice vibrations in GaN at optical frequency, and a close agreement between the computed and the experimental value of d(jj) is found. The study reveals that applications of piezoelectric nature of GaN could be extended to optical frequencies to generate phase coherent acoustic phonons to modulate thermal conduction. At optical frequencies there are no direct experimental methods exist at present for measurement of d(jj); however, the proposed relation can help to determine d(jj) from infrared reflection measurements.
原文链接:- NSTL
- Elsevier
Asif, Tariqul IslamAbu Dujana, WasifHossain, Khandaker MonowerMolla, Md Riaz...
9页查看更多>>摘要：Throughout this study the density functional theory has been employed to investigate the structural, electronic, optical, and mechanical properties of cubic halide perovskite CsYbCl3 under different hydrostatic pressure ranging from 0 to 200 GPa. The lattice constant and unit cell volume are significantly reduced due to pressure effect. The reducing tendency of band gap is also observed under pressure up to 120 GPa, but the transformation of semiconducting to metallic behavior is found for 160 and 200 GPa pressure. The tuning of band gap is responsible for enhancing the electron transfer from valence band to conduction band, which increases the optical absorption and conductivity making the compound more advantageous for device applications. The analysis of optical functions reveals that the hydrostatic pressure makes the titled compound even more suitable for various potential applications. The mechanical properties reflect the ductile and anisotropic nature of CsYbCl3, on which the applied pressure manifest substantial impact.
原文链接:- NSTL
- Elsevier
Okutan, M.Ozturk, M.Kirsoy, A.Araz, I...
6页查看更多>>摘要：Electromagnetic properties of Ce-Zn substituted barium hexaferrite (Ba0.5Ce0.5ZnFe11O19 ferrite) synthesized using ceramic technique were analyzed in detail in the X band frequencies to describe its response to microwave absorber and microwave electronic device applications. The phase formations, structural morphology, polarization mechanisms and magnetic properties for Ba0.5Ce0.5ZnFe11O19 ferrite, which provide important information about electrical load transmission mechanism were analyzed using X-ray diffraction, scanning electron microscopy, two-port vector network analyser and vibrating sample magnetometer techniques, respectively. The experimental complex dielectric plane plots (Cole-Cole plots) of the Ba0.5Ce0.5ZnFe11O19 ferrite represent an equivalent RC circuit corresponding to the impedance circuit in the Smith Chart. The reflection loss increased to the highest value (-17.04 dB) depending on the amount of Ce in the structure of the Ba0.5Ce0.5ZnFe11O19 ferrite and the bandwidth, which is important for microwave absorbers, increases.
原文链接:- NSTL
- Elsevier
