Materials Literature
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This paper describes the mechanism of discharge development in non-uniform field gap in SF 6 under positive impulses with different rising steepness. Based on theoretical consideration, an expression of the transition delay time from streamer to leader is presented, which can help to better understand the process of s…
For the formation of an ordered porous structure, the distance between two nearest neighbor pores cannot be more than a certain size, otherwise random nucleated pores arise spontaneously between ordered pores. The “proximity effect” does not allow the production of macropores with variable interpore distances on the s…
With ab initio simulations based on a real-space nonequilibrium Green's function formalism, we have investigated the charging of carbon nanotube systems. The charging effects are described by capacitance coefficients, for which we provide a first-principles estimate. Specifically, the capacitance matrix of nested armc…
Abstract A diimine ligand tethered to anthracene in the 9‐position, 4′‐(9‐anthrylethyl)‐4‐methyl‐2,2′‐bipyridine (bpy‐An), was dimerized through cycloaddition photochemistry. The resultant head‐to‐tail photodimer (bpy‐PD) was used as a bridging ligand in the preparation of a new dinuclear Ru II complex, [Ru(dmb) 2 (bp…
Charge transport (CT) in a Nafion film incorporating [Ru(bpz) 3 ] 2+ (bpz = 2,2‘-bipyrazine) was investigated using a potential-step chronocouloabsorptometry technique. The reductive CT by [Ru(bpz) 3 ] 2+/+ was found to take place by a combination mechanism of physical displacement of the complex and charge hopping be…
We report on room-temperature 1.54 µm electroluminescence, for the first time, of Er,O-codoped GaAs/GaInP double-heterostructure light emitting diodes grown by organometallic vapor phase epitaxy. The luminescence is due to intra-4 f shell transition from the first excited state to the ground state of Er 3+ ions. The e…
The aim of this work is to elucidate, through density functional calculations, the role of the Si–O interface bonds on the structural, electronic and optical properties of Si nanodots in order to explain the peculiar properties of aged porous Si samples and heavily oxidized Si nanoparticles. For isolated dots we show…
A novel approach using unoxidized porous Si (UPS) as an isolation material for mixed-signal integrated circuit applications is presented. Very thick PS can be locally fabricated without severe stress problems. Relative dielectric constants of PS are adjustable from 3 to 9 by changing porosity from 78% to 24%. PS with…
The Mulliken charges of the 12-metallacrown-3 complex [(C(6)H(6))Ru(C(5)H(3)NO(2))](3) were determined by a single point analysis at the HF level. For comparison, a Mulliken population analysis was carried out for the organic analogue 12-crown-3. The partial negative charges on the O-donor atoms of the metallamacrocyc…
Abstract An organic–inorganic hybrid material was prepared from a pentacyclo[9.5.1.1 3,9 .1 5,15 .1 7,13 ]octasiloxane bearing eight coumarin groups. The coumarin groups were photodimerized by UV‐light irradiation to connect the monomer units of the octasiloxane. Using a concentrated solution, the intermolecular photo…
The H-terminated surface of Porous Silicon (PS) has been studied in the past decade basically by means of Fourier transform infrared (FTIR) spectroscopy. In one case only, a temperature programmed desorption (TPD) technique has been applied to an n-type PS sample. However, the evaluation of the amount of hydrogen ther…
Well-crystallized LaNiO 3 (LNO) thin films were grown on thermally oxidized silicon (SiO 2 /Si) and SrTiO 3 substrates by a simple chemical solution deposition (CSD) technique. The LNO thin films obtained had pseudocubic phase without the existence of impurity phase. The LNO films on SiO 2 /Si substrates were polycrys…
This paper compares the morphologies of porous silicon and porous III–V compounds and discusses their growth mechanisms. Looking into the fine structure of pores, in silicon (meso)pores with intercalating octahedra are prevalent, while in III–V compounds chains of tetrahedra are observed. The anisotropic properties of…
[reaction: see text] A series of alpha,alpha'-bisdiarylamino-capped oligothiophenes C(n) were prepared by the palladium-catalyzed reaction of the dibromo compounds A(i) with diarylamines, N,N-diarylamino-substituted thiophenes or 2,2'-bithiophenes BX(j). These easily oxidizable compounds exhibit a high tendency to for…
Here we present a spatially directed calcination approach based on masked UV exposure to pattern mesoporous regions within a mesostructured matrix in a rapid, single-step, and inexpensive manner. Subsequent chemical treatment of the film can selectively remove the mesostructured regions, leading to patterned mesoporou…
En este trabajo, se describe el fenómeno de la degradación por corrosión electroquímica de los metales, sus efectos y costos, así como algunas de las técnicas empleadas para minimizar su impacto. Se hace énfasis en la descripción y mecanismo de acción de los inhibidores de corrosión y, con base en lo anterior, se plan…
Abstract The synthesis and characterization of liquid‐crystalline precursor polymer solutions [1] for polyimides permit for the first time the preparation of bulk‐ and surface‐oriented polyimide thin films from the nematic lyotropic state by shear. A special shearing technique was developed and optimized to orient vis…
Spectral and transient photovoltage (PV) phenomena are investigated in hydrogenated and oxidised free standing mesoporous silicon (meso-PS) layers. The size and the surface conditioning were changed systematically. The absorption tails of hydrogenated and oxidised meso-PS have been related to disorder in the bulk nano…
Porous silicon (PS) is characterized by a very large surface that is very reactive with the external environment. In this work, the chemical composition of the internal surface of both freshly anodically formed and electroplated PS with Fe and Co metals was studied. The samples were analyzed by scanning electron micro…
Self organization is a rather common phenomenon during pore formation in III–V semiconductors. The so called tetrahedron-like pores, the domains of crystallographically oriented pores in n-GaAs, or the macroscopic voltage oscillations in n-InP at high constant current densities are examples of a self organization proc…