Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We report lifetimes of optical phonons (OPs) in graphene and graphite measured by time-resolved anti-Stokes Raman scattering. Lifetimes in graphite and monolayer graphene are 2.4 and 1.2 ps, respectively. For graphite and graphene with more than five layers, the lifetimes decrease with increasing temperature as $\ensu…
Graphene is a 2-dimensional material with high carrier mobility and thermal conductivity, suitable for high-speed electronics. Conduction and valence bands touch at the Dirac point. The absorptivity of single-layer graphene is 2.3%, nearly independent of wavelength. Here we investigate the thermal radiation from biase…
The quantum spin Hall (QSH) state, observed in a zero magnetic field in HgTe quantum wells, respects the time-reversal symmetry and is distinct from quantum Hall (QH) states. We show that the QSH state persists in strong quantizing fields and is identified by counter-propagating (helical) edge channels with nonlinear…
In an organic blend the vibrational normal mode excited by exciton splitting is the same as the one coupled to charge hopping. Excess driving force for exciton splitting can therefore aid charge transfer, if vibrational relaxation is slow compared to charge transfer. A model is developed that takes this into account a…
We have achieved the creation of a solid-solution alloy where Pd and Pt are homogeneously mixed at the atomic level, by a process of hydrogen absorption/desorption as a trigger for core (Pd)/shell (Pt) nanoparticles. The structural change from core/shell to solid solution has been confirmed by in situ powder X-ray dif…
The structure of the commensurate (23x23) phase of graphene on Ru(0001) has been analyzed by quantitative low-energy electron diffraction (LEED)-I(V) analysis and density-functional theory calculations. The I(V) analysis uses Fourier components as fitting parameters to determine the vertical corrugation and the latera…
A lead‐free piezoelectric 0.91(Bi 1/2 Na 1/2 )TiO 3 –0.06BaTiO 3 –0.03(K 0.5 Na 0.5 )NbO 3 ceramic with high strain was examined in situ under an applied electric field using the transmission electron microscope. No domain structure is observed without an electric field, but an alternating electric field leads to the…
We use magnetic long-range order as a tool to probe the Cooper-pair wave function in the iron arsenide superconductors. We show theoretically that antiferromagnetism and superconductivity can coexist in these materials only if Cooper pairs form an unconventional, sign-changing state. The observation of coexistence in…
Nanocrystalline cellulose (NCC) is extracted from woody biomass using acid hydrolysis. It has unique strength and distinctive optical/conductive/magnetic properties. When a suspension of NCC is air-dried, it forms a film with unique characteristics (e.g., iridescence) linked to the formation of chiral nematic structur…
The transformation of Ni nanoparticles (NPs) of different sizes (average diameters of 9, 26, and 96 nm) during oxidation to hollow (single void) or porous (multiple voids) NiO through the nanoscale Kirkendall effect was observed by transmission electron microscopy. Samples treated for 1-4 h at 200-500 degrees C show t…
We have investigated the effects of doping on a single layer of graphene using angle-resolved photoemission spectroscopy. We show that many-body interactions severely warp the Fermi surface, leading to an extended van Hove singularity (EVHS) at the graphene M point. The ground state properties of graphene with such an…
Direct deposition of graphene on various dielectric substrates is demonstrated using a single-step chemical vapor deposition process. Single-layer graphene is formed through surface catalytic decomposition of hydrocarbon precursors on thin copper films predeposited on dielectric substrates. The copper films dewet and…
Photoluminescent materials were prepared by introducing lanthanide complexes of 4'-formylbenzo-15-crown-5 (C15H20O6) into a silica matrix obtained by the sol-gel method. The new lanthanide complexes [Ln(C15H20O6)(NO3)3(H2O)2] (Ln3+ = Sm3+, Eu3+ and Tb3+) were synthesized and were fully characterised using spectroscopi…
Abstract In one of the gas processing facilities in Abu Dhabi, UAE; a case of 316L stainless steel material failure occurred in the fractionating column due to stress cracking corrosion twice in a cycle of less than 2 years. This paper studies the stress corrosion cracking behavior of the 316L stainless steel in an ac…
This paper describes an experimental study on the performance of sulfamic acid and citric acid in scale removal of Dura refinery heat exchange piping systems. Experiments were carried out using sulfamic acid and citric acid inhibited by hexamine as cleaning solutions at different time, temperature and concentrations.…
본 논문에서는 마그네슘합금 재료로 제작된 F-5E/F의 외부 연료탱크 수평 핀의 균열 발생 원인을 분석하고 적절한 대체 재질을 검토하여 탱크의 투하 안전성을 보장하도록 핀의 형상을 재설계하였다. 재료는 재료의 성질과 조달 용이성을 고려하여 강도 및 파괴 인성이 기존재료보다 강하지만 핀 1개당 65%의 무게증가가 예상되는 알루미늄 합금 2024-T351을 선택하였다. 핀의 무게 증가로 인한 연료탱크 무게 중심의 후방 이동을 허용한계 이내로 유지하기 위하여 크기를 20% 축소하고, 두께 7 mm, 곡률 반경 8.5 mm로 설계된 핀에 대하여 정적 및 동적 응력을 해석한…
A cold-extruding and temper means was developed in order to densify the Ti3AlC2 toughened Cu matrix composites with a lower content of Ti3AlC2 ceramic. The Ti3AlC2/Cu samples, with 10%, 15% and 20% of Ti3AlC2 in volume ratio, ware prepared by pressless sintering a mixture of copper and Ti3AlC2 powders, after which wer…
In this work thin ZnO layers were grown by metal-organic PECVD (RF 13.56 MHz) on Si wafers. Zn acetylacetonate was used as a precursor and oxygen as oxidant. A system for dosed injection of the precursor and oxidant into the plasma reactor was developed. The influence of the substrate surface topology and temperature…
Abstract The article deals with the influence of heat flux on localised forms of corrosion of stainless steels under the conditions of phase transition on a metal surface. The observations focused on the influence of the initiation and propagation of pitting corrosion and stress corrosion cracking. Pitting corrosion w…
We report here the preparation of fibrous gold nanoparticles-polyaniline (PANI) nanorod composite as an extension of our previous work in nanostructured conducting polymers. We have been able to control the amount of gold particles and the density of nanofibers covering the surface of the nanorods, which are character…