Dielectric oxides

Chemically pure semiconducor materials can absorb only those photons, the energy hv of which exceeds the band gap E . Therefore, E. value determines the "red boundary of the light that is used in photocatalytic action of these materials. By way of example. Table 1 presents the values of Eg and the corresponding values of boundary wave length Xg= hc/E (where c is the velocity of light) for some semiconductor and dielectric oxides [2]. However, a semiconductor PC can be sensitized to light with X> by chemical modifications of its surface layer or adsorption of certain molecules on its surface, provided that such treatment creates additional full or empty electron levels in the band gap of the semiconductor material. 

Band gaps and "red" boundaries X of the optical absorption for typical semiconductor and dielectric oxides [2]... 

NHE OCP ONO OPS PCD PDS PL PLE PMMA PP PP PS PSG PSL PTFE PVC PVDF normal hydrogen electrode (= SHE) open circuit potential oxide-nitride-oxide dielectric oxidized porous silicon photoconductive decay photothermal displacement spectroscopy photoluminescence photoluminescence excitation spectroscopy polymethyl methacrylate passivation potential polypropylene porous silicon phosphosilicate glass porous silicon layer polytetrafluoroethylene polyvinyl chloride polyvinylidene fluoride... 

A dielectric oxide layer (eg. silica) is useful as a shell material because of the stability it lends to the core and its optical transparency. The classic method of Stober for solution deposition of silica are adaptable for coating of nanocrystals with silica shells.111 This method relies on the pH and the concentration of the solution to control the rate of deposition. The natural affinity of silica to oxidic layers has been exploited to obtain silica coating on a family of iron oxide nanoparticlcs including hematite and magnetite111 Such a deposition process is not readily extendable to grow shell layers on metals. The most successful method for silica encapsulation of metal nanoparlides is that due to Mulvaney and co-workers.114 In this method, the surface of the nanoparticles is functionalized with aminopropyltrimethylsilane. a bifunctional molecule with a pendant silane group which is available for condensation of silica. The next step involves the slow deposition of silica in water followed by the fast deposition of silica in ethanol. Fig. 13 shows the TEM images... 

W. Ong, S.Robles, S. Sdhn, B. C. Nguymi Characterization of Inter-metal and Pre-metal Dielectric Oxides for Chemical Mechanical Polishing Process Integration , Proc. of lEEE-VMIC (1993) P.197... 

The bulk oxygen content in the Ta anode strongly affects this crystallization process in the dielectric oxide film [249, 250], If the oxygen concentration in the bulk approaches the solubility limit (about 3.200 wt. ppm for Ta at room... 

We now consider the interface between carrier and toner, as these components interact in a dynamic development system. As we have noted, toner is commonly fabricated by "jet impacting" a brittle pigmented thermoplastic to form irregularly shaped particles of about 12/u m cross-section--particles whose surface comprises resin and carbon black (2, J 3, 58). The carrier cores are magnetic (ferrite or steel), typically about 250/4 m in size and therefore relatively massive. They are generally coated with a dielectric oxide or resin, which participates in the tribo-electrification process (2, it , 59). ... 

With such all-dielectric oxide systems, thermal loads up to about 400°C are readily feasible. 

Ormosils can possess excellent transparency when processing conditions are optimized. Moreover, they are typically nonporous. Their properties, as well as their low-temperature processing, make them ideal candidates as optical host media for a wide range of optically active species. These include laser dyes [51,53,55], photochromic molecules [52], second-harmonic-generating dielectric oxides [54], semiconductor quantum dots [53], and metallic quantum dots... 

Venkatesan, M., Fitzgerald, C.B., Coey, J.M.D. Thin films unexpected magnetism in a dielectric oxide. Nature 430, 630 (2004)... 

Enhancement of photostability of organic dye molecules has been observed in polymer matrices co-doped with dielectric oxide microparticles (Ahmad, 2007). Duarte and James (2003,2004) demonstrated a class of dye-doped organic-inorganic solid-state gain media based on silica nanoparticles uniformly dispersed in poly(methyl... 

The four methods commonly used utilize hole waU epoxy or dielectric oxidation, neutralization-reduction, and glass etching. Three of the four common methods employ technology that... 

Jeon N.L., Clem P.G., Payne D.A., Nuzzo R.G. Patterning of dielectric oxide thin layers by microcontact printing of self-assembled monolayers. J. Mater. Res. 1995 10 2996-2999... 

For thin dielectrics, which are used for low voltage polymer capacitors, the quality of the dielectric oxide layer can be restored by the reformation or aging process for thicker dielectrics (capacitors with voltage rating of 25 V or higher) the restoration typically fails. The application of an insulating protection layer on the dielectric can help to reduce the degradation of the dielectric by chemical polymerization. ... 

Model for degradation of high-voltage dielectric oxide layer. Left scheme of model right pinhole painted into SEM picture of broken oxidized Ta particle. 

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