Materials Literature
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An expression of refractive indices for AlGaAs is presented which agrees reasonably with the experimental results by H. C. Casey Jr., D. D. Shell, and M. B. Panish [Appl. Phys. Lett. 24, 63 (1974)]. This expression is approximately derived by using the method of least squares and is applicable to a determination of th…
The purpose of the present paper is to report the crystal structure of a new phase of tetralithium diphosphate identified by single-crystal X-ray diffraction. The structure consists of layers built from Li—O tetrahedra and pyrophosphate groups connected to each other through edges and vertices.
We present an extension of the configurational bias Monte Carlo method for the efficient simulation of off–lattice polymer systems. Elementary moves consist in regrowing internal segments of a polymer chain. We show that the method satisfies the detailed balance condition. We apply it to three well known simple models…
The exciton and two-exciton states in semiconductor quantum dots much larger in size than the exciton Bohr radius are investigated, and the energies and oscillator strengths of several exciton and biexciton states are calculated. The presence of weakly correlated exciton-pair states are identified and these have a lar…
Although the AlxGa1−xAs alloy system has been extensively investigated, there are still considerable uncertainties in measuring the value of x. Here a new AlxGa1−xAs calibration structure, grown by molecular beam epitaxy, has been used to establish unambiguous alloy compositions. Such “standard’’ AlxGa1−xAs layers wer…
We present theoretical results for the frequency-dependent dielectric response, both for the electric field parallel and perpendicular to the c axis of graphite. The calculations are performed using a full-potential linear muffin-tin orbital method. Our calculations show fair agreement with experimental data and the d…
Silica glasses were repeatedly densified by multiple shock reverberations in stainless-steel capsules. The limit of increase in density was about 2.47 Mg/m3 after the first shock loading. Further increase in density was observed after duplicate shock loading, but limited at about 2.55 Mg/m3. Triplicate shock loading w…
We used x-ray photoelectron spectroscopy to investigate the chemistry of O impurity atoms in CdS thin films grown for photovoltaic purposes by chemical-bath deposition (CBD). We compared the Cd 3d photoline, O 1s photoline, Cd MNN Auger line, and O KLL Auger line taken from a CBD CdS thin film, CdS single-crystal refe…
Recent advances in material synthesis have provided samples with CdSe quantum dots with a degree of monodispersity high enough to allow for observation of excited exciton states and their size dependence [Norris et al., Phys. Rev. Lett. 72, 2612 (1994)]. Here we report theoretical results for these exciton states usin…
The stress distribution in heteroepitaxial chemical vapor deposited diamond films has been investigated by Raman spectroscopy. A new method for stress determination based on polarized confocal micro-Raman is presented and used for the measurement of the stress evolution across the film thickness in the center of the s…
We present here the topological (Bader) analysis of the electronic structure for 120 cubic perovskites ${\mathrm{AMX}}_{3}$ (A denotes Li, Na, K, Rb, Cs; M denotes Be, Mg, Ca, Sr, Ba, Zn; X denotes F, Cl, Br, I). The perovskite being perhaps the simplest and most abundant structure for ternary compounds, we have found…
Optical conductivity spectra and their variation with temperature and doping level x have been investigated for single crystals of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Sr}}_{\mathrm{x}}$${\mathrm{MnO}}_{3}$n(0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.3). For the low-doped insulating cryst…
Fine powders of ZnFe2O4 with an average particle size of 10 nm and inversion parameter of 0.21 were synthesized by the aerogel procedure. Portions of the powders were calcined in air at 500 and 800 °C and other portions were ball-milled for 10 h. The materials were characterized by x-ray diffractometry, vibrating samp…
We have studied the electronic structure of ${\mathrm{LaCoO}}_{3}$ by photoemission spectroscopy and x-ray absorption spectroscopy (XAS). The Co 2p core-level and valence-band photoemission spectra display satellite structures indicating a strong electron-correlation effect. The Co 2p core-level photoemission, the val…
Laser ablation of (Co,Ni)-doped graphite yields \ensuremath{\sim} 70% single-wall nanotubes, predominantly (10,10) armchair tubes which self-organize into crystalline ``ropes''>100 \AA{} in diameter and>10 \ensuremath{\mu}m long. We find ${\mathrm{\ensuremath{\rho}}}_{\mathrm{\ensuremath{\Vert}}}$=0.03-0.10m\ens…
We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum thermal expansion, zero ther…
Molecules that behave like large atoms!—molecules of the mixed anhydride formed from the acids tBuP(O)(OH)2 and PhB(OH)2 exhibit this characteristic since in the crystal lattice they occupy the corners and centers of weakly distorted cubooctahedra. The molecules reveal a cubane framework (depicted on the right), whose…
Phosphorus containing polyimides were prepared via phosphorylation of organosoluble polyimides. This was achieved by phenoxaphosphine oxide ring formation reaction or esterification with diethylchlorophosphate. The phosphorylation was confirmed by infrared, 31P nuclear magnetic resonance, and elemental analysis for ph…
The aim of this study was to prepare a compatibilized PP/PBT blend in a twin-screw extruder, using oxazoline-functionalized PP. First we prepared the functionalized PP (PP-g-OXA), and then we used it as a compatibilizer in the subsequent reactive blending stage. Polypropylene was successfully functionalized by ricinol…
100 μm porous p(styrene-co-divinylbenzene) (PS-DVB) microspheres were synthesized by employing a particular membrane emulsification technique, and subsequent swelling of the seed droplets. DVB dissolving a water-insoluble substance, hexadecane (HD), and an initiator was permeated through a SPG (Shirasu porous glass) m…