Materials Literature
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The BiFeO3 ceramics were prepared by sol-gel method (BFO-1) and high-pressure synthesis (BFO-2). X-ray diffraction showed that these ceramics are almost of single phase. It is difficult to observe a ferroelectric loop of BFO-1 even at an electric field of 6kV∕cm. Compared to BFO-1, the high-pressure synthesized one ha…
In this work, the authors study the stability and electronic properties of CuxTe as a function of the Cu∕Te ratio using first-principles calculations. They find that CuxTe shows bistability with energy minimum at x≈1.25 and x≈1.75. At low x, CuxTe is more stable in the tetragonal-based structures, whereas for x&gt…
Zinc dicyanide, $\mathrm{Zn}{(\mathrm{C}\mathrm{N})}_{2}$, and the isostructural cadmium dicyanide show negative thermal expansion over a broad range of temperatures. By the use of density functional theory calculations, we determine the phonon dispersion curves of these materials and show that the transverse acoustic…
The effects of Sr substitution for Ba on photocatalytic water splitting activity of BaSnO3 were investigated experimentally and theoretically. The chemical incorporation of Sr into BaSnO3 induced a great enhancement for H2 production. Density function theory calculations of Ba1−xSrxSnO3 (x=0, 0.5, and 1.0) reveal that…
Mn-doped ZnO films with preferred c-axis growth orientation were prepared by pulsed laser deposition under N2 atmosphere on a-plane sapphire substrates. Large positive magnetoresistance amounting to 60% was observed at 5K. Clear anomalous Hall effect was observed at 20K. Ferromagnetism with Curie temperature higher th…
Carbon nanotube transistor (CNT) is promising to be the technology of choice for nanoscale integration. In this work, we develop the first compact model of CNT, with the objective to explore the optimal process and design space for robust low-power applications. Based on the concept of the surface potential, the new m…
According to the numerical calculation, the relative phase of emitting light scattered by surface plasmon in a single subwavelength metallic groove can be modulated by the groove depth. The focal length of the slit-groove-based focusing structures can be adjusted in certain value if the groove depths are arranged in t…
The effects of ultraviolet (UV) irradiation on the work function of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) have been investigated in this study. Spectroscopic methods [x-ray photoelectron spectroscopy and Raman spectroscopy (532nm excitation)] and electrical conductivity measu…
A silicon-nanocrystal (nc-Si) based metal-oxide-semiconductor light-emitting diode (MOSLED) on Si nanopillar array with size, height, and density of 30nm, 350nm, and 2.8×1010cm−2, respectively, is characterized. The nanopillar roughened Si surface contributes to the improved turn-on characteristics by enhancing Fowler…
This letter reports blue oxynitride phosphors of La1−xCexAl(Si6−zAlz)(N10−zOz) (z∼1) (termed JEM crystal phase) and their application for the white light-emitting diodes (LEDs). The JEM phosphor can be excited by 405nm light efficiently, and its spectrum can be tuned widely by changing the Ce concentration. The emissi…
Photoluminescence properties of silicate and borosilicate glasses codoped with Tb3+ and Sm3+ ions have been characterized by excitation and emission spectroscopies. When excited by ultraviolet light the glasses emit a combination of green and orange-red wavelengths giving white light. The ratio of the intensities of o…
A large variety of engaging phenomena, ranging from crystallization in protein solutions to the formation of colloidal gels and glasses via depletion forces, stems from the occurrence of very short-ranged attractive forces. From depolarized light scattering measurements of equilibrium sedimentation profiles, we obtain…
Carbon nanotube transistors show tremendous potential for electronic detection of biomolecules in solution. However, the nature and magnitude of the sensing signal upon molecular adsorption have so far remained controversial. Here, the authors show that the choice of the reference electrode is critical and resolves mu…
We investigate the hydrogen absorption capacity of two tubular structures, namely, $\mathrm{B}∕\mathrm{Be}$-substituted single-wall carbon nanotube (SWNT) and Ti covered single-wall boron nitride nanotube (SWBNT) using first-principles plane wave method. The interaction of ${\mathrm{H}}_{2}$ molecules with the outer s…
The electron doping of undoped high-${T}_{c}$ cuprates via the transfer of charge from manganites (or other oxides) using heterostructure geometries is discussed theoretically here. This possibility is mainly addressed via a detailed analysis of photoemission and diffusion voltage experiments, which locate the Fermi l…
Contact algorithm between different bodies plays an important role in solving collision problems. Usually it is not easy to be treated very well. Several ones for material point method were proposed by Bardenhangen, Brackbill, and Sulsky\cite{Bardenhagen2000,Bardenhagen2001}, Hu and Chen\cite{Hu_Chen2003}. An improved…
Germanium nanocrystals may be of interest for a variety of electronic and optoelectronic applications including photovoltaics, primarily due to the tunability of their band gap from the infrared into the visible range of the spectrum. This letter discusses the synthesis of monodisperse germanium nanocrystals via a non…
We present a study of the paramagnetic metallic and insulating phases of vanadium sesquioxide by means of the $N\mathrm{th}$ order muffin-tin orbital implementation of density functional theory combined with dynamical mean-field theory. The transition is shown to be driven by a correlation-induced enhancement of the c…
The band-gap problem and other systematic failures of approximate functionals are explained from an analysis of total energy for fractional charges. The deviation from the correct intrinsic linear behavior in finite systems leads to delocalization and localization errors in large or bulk systems. Functionals whose ene…
A method to calculate NMR J-coupling constants from first principles in extended systems is presented. It is based on density functional theory and is formulated within a planewave-pseudopotential framework. The all-electron properties are recovered using the projector augmented wave approach. The method is validated…