Materials Literature
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The structural stability and electronic structure of face-centered-cubic Ti, Zr, and Hf were studied by means of first-principles full-potential calculations. The total-energy calculations demonstrate that Ti, Zr, and Hf have a locally stable fcc structure, i.e., the elastic stability criteria for a cubic crystal are…
We consider the question of whether a two-dimensional hard-disc fluid has a first-order transition from the liquid state to the solid state as in the three-dimensional melting-crystallization transition or whether one has two subsequent continuous transitions, from the liquid to the hexatic phase and then to the solid…
Thick (~50 nm) films of Hf were evaporated onto bare and oxidized Si(001) samples, and thin (~monolayer) films of Hf were evaporated onto clean Si(001)-(2x1) surfaces. Upon annealing to 1000$^/circ$C, films of HfSi2 were formed after reaction times that depended upon the surface condition of the substrate before depos…
Field emission (FE) electron spectroscopy from an individual multiwalled carbon nanotube (MWNT) is used to measure quantitatively stable temperatures at the apex, T(A), of up to 2000 K induced by FE currents approximately 1 microA. The high T(A) is due to Joule heating along the length of the MWNT. These measurements…
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Periodic density functional calculations on three sodalites [Cd 4 S(AlO 2 ) 6, Zn 4 O(BO 2 ) 6, and Zn 4 S(BO 2 ) 6 ] were performed. Lowest-energy allowed electronic transitions were always found to be localized on the M 4 X (M = Cd, Zn; X = O, S) clusters encapsulated into lattice cages. Predicted excitation energie…
Laser action in a dye-doped ferroelectric liquid crystal (FLC)—at the edge of the photonic stop band—has been demonstrated for the first time. The FLC used is a multicomponent mixture with a well-controlled short pitch of its helical structure whose periodic is equivalent to visible optical wavelengths. The laser emis…
In this paper, we report on diamond microtubes that have been manufactured to work as flow controllers in choking conditions. Tungsten wires are used as moulds to make the diamond microtubes. A continuous diamond film has been deposited by chemical vapour deposition, and acid etching of the tungsten has been performed…
Pressure effects on the structural parameters are investigated in a half-doped manganites $({\mathrm{Nd}}_{0.125}{\mathrm{Sm}}_{0.875}{)}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3},$ by means of the synchrotron-radiation x-ray powder diffraction measurement. The compound shows a pressure-induced metal-insulator transi…
The synthesis and structural characterization of a new precursor solid solution SrAl2 − xBxO4 (0 < x < 0.2), for phosphor materials is reported. The synthesis temperature of SrAl2O4 is considerably reduced by B substitution. The new solid solution keeps the tridymite-like structure (P21) characteristic of SrAl2O4. Mic…
The doorway window representation of sequential four wave mixing combined with the nonlinear exciton equations (NEE) is used to calculate femtosecond pump probe spectra of the dendrimeric nanostar. Direct signatures of exciton funneling and the two-exciton states are identified. The frequency-domain pump−probe signal…
We report the first computational study of the chromophores responsible for the chromogenic effects of aromatic neurotoxicants containing a 1,2-diacetyl moiety in their oxidation metabolites. A series of ab initio electronic structure calculations was performed on two representative aromatic compounds, 1,2-diacetylben…
An attempt to rationalize the behaviour of iron(II) spin-crossover compounds under hydrostatic pressure at room temperature from a comparative analysis of data is reported. The selected pressure-induced spin transitions are those previously described for Fe(phen)2(NCS)2 [polymorphs I (a) and II (b)], Fe(py)2bpym(NCS)2…
Thin-film semiconducting devices containing inorganic as well as organic layers have been fabricated via solution processing (see Figure). Using high work function transition metal dichalcogenides (TMDCs) it is possible to reduce the barrier to hole injection into the polymer. A blocking barrier layer can be introduce…
Tellurium nanotubes with well-controlled structures (see Figure) are obtained via concentration depletion at the surfaces of seeds. The lengths of these inorganic nanotubes can be varied by adjusting the growth time (see cover), and the outer diameters of the tubes can be controlled by changing the initial concentrati…
We have calculated the pair-correlation functions of a fluid interacting via the Gay-Berne (n-6) pair potentials using the Percus-Yevick integral equation theory and have shown how these correlations depend on the value of n that measures the sharpness of the repulsive core of the pair potential. These results have be…
Pulsed IR laser-induced ablation of bulk poly[oxy(tetramethyldisilane-1,2-diyl)], [(CH 3 ) 2 Si(CH 3 ) 2 SiO] n,yields thin polyoxocarbosilane films whose polymeric structure consists of a backbone composed of −(CH 3 ) 2 Si(CH 3 ) 2 SiO− and −O(CH 3 ) 2 SiO− units, which is cross-linked via SiSiC 2 O, C 3 SiO, C 2 SiH…
The cluster [Ag(SC6H2Pri(3)-2,4,6)]10 (1) contains a 20-membered ring of alternating silver and sulfur atoms, which is compactly folded; the sulfur atoms are doubly bridging and each silver atom exhibits linear two-coordination in the primary Ag-S interactions.
Four rate-limiting processes for the formation of single-wall carbon nanotubes (SWCNT) could be identified by varying furnace temperature, gas type, and pressure in a pulsed-laser evaporation setup. One rate-limiting process accounts essentially for all relevant gas-pressure dependencies and can be quantitatively desc…
Arrays of alumina nanopillars with adjustable dimensions (see Figure for a representative example) are fabricated by simple chemical etching of porous anodic alumina with dilute NaOH. The diameter and height of the pillars, as well as interpillar spacing, are a function of the oxide layer thickness, which is controlle…