Materials Literature
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Poly(vinyl chloride- co -vinyl acetate- co -maleic acid) (vinyl chloride 83%, vinyl acetate 13%, carboxylated 1%) was found to be a substrate favoring the deposition of vaterite crystals from stable supersaturated solutions at pH 8.50 and 25 °C. Induction times preceding calcium carbonate precipitation were inversely…
Deprotonated and protonated forms of L-tyrosine or L-phenylalanine were intercalated by Zn-Al hydrotalcite (HT) and Na-montmorillonite (Na-mont), respectively. The intercalated materials were characterized by powder X-ray diffraction, BET measurements, and FT-IR spectroscopy. Intercalation was successful as the increa…
Radical solution polymerization of triallyl isocyanurate was conducted in methyl benzoate or hexyl benzoate as good or poor solvent, respectively, using AIBN as initiator at 60°C. An increased rate of polymerization, enlarged primary chain length, and promoted gelation were observed in the poor solvent. The actual gel…
A design method is presented that enables the realization of a novel type of incoupling waveguide hologram (IWGH) that simultaneously focuses the incoupled light to any desired positions in the waveguide. IWGH's, or grating couplers, are gratinglike structures etched into the waveguide surface. They couple the light i…
Charge trapping induced by hot carriers in a metal–oxide–semiconductor capacitor was studied with a scanning capacitance microscope (SCM). The local charge trapping/detrapping and the readout of the trapped charge in SiO2 was performed using a SCM combined with an atomic force microscope. When applying a voltage betwe…
Using tight-binding molecular dynamics, we have constructed structural models of amorphous carbon surfaces, by imposing tensile strain on computer generated networks containing 512 carbon atoms until fracture is produced and two surfaces are formed. Different tensile strains are applied along different directions, in…
We demonstrate the existence of intrinsic gap states in bare and capped semiconductor nanocrystals within multiband effective mass theory. These states originate from Shockley-like surface states which, in small nanocrystals, extend over the entire crystal volume, facilitating their observation in absorption as well a…
Leakage conduction of (Pb, La)(Zr, Ti)O3 (PLZT) films grown on Pt bottom electrode, with Pt and Pt/SrRuO3 (Pt/SRO) top electrodes is studied. It is found that the conduction behavior of the ferroelectric capacitors strongly varies depending on the degree of interdiffusion from the electrode into the ferroelectric mate…
We observed the quantum-confined band edge emission from ZnSe quantum dots and the size dependence of the energy states, spin-orbit interaction, and Stokes shift. The band edge emission occurs in the ultraviolet blue. The energy gap=Eg+C/dn where d is the diameter and n is 1.19±0.13 and 1.21±0.13 for the first and sec…
We directly show the evolution of the electronic structure of semiconductor quantum dots (QDs) with QD size in the strong confinement regime by employing low-temperature tunneling current–voltage spectroscopy to individual electrodeposited CdSe QDs. From the spectra we measure the values of Eg, map discrete energy lev…
We present new results on the zero-field magnetic relaxation in a single crystal of M${\mathrm{n}}_{12}$ acetate. We find three relaxation regimes. Above 2.8 K, the relaxation is exponential. Below this temperature, deviations are observed. These deviations are more pronounced when temperature decreases between 2.4 an…
The luminescence characteristics of laser-created bubbles in water have been studied for pressures between 1 and 15 bars. A fast peak in the luminescence is correlated with the first collapse point of the bubble. The width of the light pulse is several nanoseconds, and increases with the bubble size. With increasing p…
We have used an aqueous colloidal growth technique to form hybrid CdTe/HgTe quantum dots with a broad, strong fluorescence in the infrared (800–1200 nm). The quantum efficiency is high, around 44%, when pumped in the visible (488 nm), and the excited state lifetime is around 130 ns, making the material interesting as…
The biaxial and uniaxial magnetic anisotropy in epitaxial (100)-oriented La0.7(Sr, Ca)0.3MnO3 films on different substrates were measured by torque magnetometry in the range from T=20 K to room temperature. The biaxial anisotropy with easy axes 〈110〉 dominates and can be described by a cubic crystal anisotropy constan…
Ferroelectric BaTiO3 thin films with perovskite structure were grown by sol-gel spin-on processing onto (111)Pt/Ti/SiO2/Si substrates. In order to investigate the effects of space charge in BaTiO3 thin films, we measured the relative dielectric constant and the ac conductivity of the films as a function of frequency,…
A fundamental limitation on the recent development of nonvolatile ferroelectric memories in 64 Mbit–4 Gbit densities has been the ability to scale ferroelectric capacitor cell sizes below 1 μm2. In the present work, ferroelectric memory cells with lateral sizes down to 100 nm were fabricated by electron-beam direct wr…
Long-lasting phosphorescence is observed in Ce3+-doped Ca2Al2SiO7 (CASM) and CaYAl3O7 (CYAM) crystals at room temperature. UV irradiation at 365 nm produces broadband emissions with peaks at 417 nm for CASM and 425 nm for CYAM, which persist for not less than 1 h after the removal of the irradiating light. Based on th…
Accurate atomic coordinates of the room-temperature (root3xroot3)R30degree and low-temperature (3x3) phases of 1/3 ML Sn on Ge(111) have been established by grazing-incidence x-ray diffraction with synchrotron radiation. The Sn atoms are located solely at T4-sites in the (root3xroot3)R30degree structure. In the low te…
A detailed structural model for the indium-induced Si(111)-(4x1) surface reconstruction has been determined by analyzing an extensive set of x-ray-diffraction data recorded with monochromatic ($\hbarω$ = 9.1 keV) synchrotron radiation. The reconstruction is quasi-one-dimensional. The main features in the structure are…
The Mn-terminated (001) surface of the stable anti-ferromagnetic insulating phase of cubic perovskite CaMnO$_3$ is found to undergo a magnetic reconstruction consisting on a spin-flip process at surface: each Mn spin at the surface flips to pair with that of Mn in the subsurface layer. In spite of very little Mn-O cha…