Niobium polymers

Zirconium and niobium polymers were prepared by fairly similar routes, the ammonolysis of the tetrakis-dialkylamines [88] or the chlorides [89,90] in liquid ammonia. After pyrolysis, nitrides or carbonitrides were obtained in high ceramic yields. 

These consist of a number of parallel slots cut into the concrete surface. Each slot is then filled with a secondary anode of carbon/graphite fibres embedded in a conductive polymer grout. The current to each of these secondary anode systems is provided by a primary anode of platinised niobium wire placed in slots filled with conductive polymer which acts as the primary anode, these slots intersecting each slot of graphite fibre/conductive polymer at right angles. 

Conductive paints (resins) have recently been used for the cathodic protection of steel reinforcing bars in concrete, but they are always used in conjunction with a primary anode material, e.g. platinised-niobium or platinised-titanium wire or a conductive polymer rod. 

Pike, G., Pierson, H. O., Mullendore, A., and Schirber, J., Superconducting Thin Film Niobium Carbonitrides on Carbon Fibers, / / . Polymer Symp., No. 29, pp. 71-81, John Wiley Sons, New York (1976)... 

K.J. Reynolds, G.L. Frey, and R.H. Friend, Solution-processed niobium diselenide as conductor and anode for polymer light-emitting diodes, Appl. Phys. Lett., 82 1123-1125, 2003. 

Finally the ESR spectrum of Nb(7r-allyl)4/alumina was unaffected by the addition of ethylene gas to the ESR sample tube. It is assumed that polyethylene is produced in this process since polymer can be isolated from larger scale reactions under similar conditions. The accepted mechanism for the ethylene growth reaction postulates a steady-state concentration of a a-bonded transition metal-hydrocarbon species which would be expected to modify the ESR spectrum of the supported complex. A possible explanation for the failure to detect a change in the ESR spectrum may be that only a small number of the niobium sites are active for polymerization. Although further experiments are needed to verify this proposition, it is consistent with IR data and radiochemical studies of similar catalyst systems (41, 42, 43). 

Acetyl ligands, in niobium complexes, C-H BDEs, 1, 298 Achiral phosphines, on polymer-supported peptides, 12, 698 Acid halides, indium compound reactions, 9, 683 Acidity, one-electron oxidized metal hydrides, 1, 294 Acid leaching, in organometallic stability studies, 12, 612 Acid-platinum rf-monoalkynes, interactions, 8, 641 Acrylate, polymerization with aluminum catalysts, 3, 280 Acrylic monomers, lanthanide-catalyzed polymerization,... 

Complexation studies (continued) polymer backbone, 1, 258 polymerization monitoring, 1, 259 pulse radiolysis initiation, 1, 535 in thin film and wire depositions, 1, 259 valence and oxidation number, 1, 18 t/-Complexes with niobium, 5, 66, 5, 68 with tantalum, 5, 108... 

Martin and Murphy ° compared twenty-five different solid lubricant composites for use in small arms. The best performance was obtained with a composite of molybdenum disulphide in molybdenum with niobium and copper. This had a lower wear rate (0.224 x 10 mm /Nm) and lower coefficient of friction (0.05 - 0.15) than any of the twenty-one polymer-based composites. 

Pasche, S. et al., Poly(L-lysine)-graft-poly(ethylene glycol) assembled monolayers on niobium oxide surfaces A quantitative study of the influence of polymer interfacial architecture on resistance to protein adsorption by ToF-SlMS and in situ OWLS, Langmuir, 19, 9216, 2003. 

Nonoverlay slotted anode system used platinized-niobium-copper wire anode laid in regularly spaced slots designed to distribute CP current evenly to the rebar mat and was filled with a conductive polymer concrete. Estimated cost is 92/m and 15 years of service life. 

Conductive polymer mound anode system used platinized-niobium copper wire anode with the conductive polymer mounded on wire anode and rigid concrete overlay on top. Estimated cost is 137/m with a service life of 20 years. 

Other anode systems specially developed are sprayable conductive polymer coatings, metallized zinc coatings, and conductive paints. Typical primary anode for the conductive polymer or paints is platinized niobium wire attached to the concrete prior to application. Estimated cost is 76/m with a service life of five years. 

Superconductivity has been observed in all the classes of materials metals, ceramics, and polymers. Of all the elements in the periodic table only 27 are known to become superconducting under ordinary pressure. Niobium is the element with the highest T, 9.2 K, whereas for tungsten Tc is only 0.0154 K. An interesting fact is that metals having the highest o, e.g., Cu, Ag, and Au, are not superconducting even at extremely low temperatures, if at all. It is the metals that are the poorer electrical conductors that make... 

Corrosion of the plates not only detracts from their mechanical properties but also gives rise to undesirable corrosion products, namely, heavy-metal ions, which, when depositing on the catalysts, strongly depress their activity. The corrosion processes also give rise to superficial oxide films on the metal parts, and these cause contact resistance of the surfaces. For a lower contact resistance, metallic bipolar plates sometimes have a surface layer of a more stable metal. Thus, in the first polymer electrolyte membrane fuel cell, developed by General Electric for the Gemini spacecraft, the bipolar plates consisted of niobium and tantalum coated with a thin layer of gold. A bipolar plate could also be coated with a layer of carbide or nitride. 

One of the most widespread technical applications of PEDT is its use as a counterelectrode in solid aluminum, tantalum, and niobium electrolytic capacitors. As early as 1988, the application of PEDT as polymeric counter electrode in a tantalum capacitor was described in a patent application [62]. Since then, more than 100 patent applications have been filed which claim the use of PEDT in various capacitor configurations, and most major capacitor manufacturers today produce polymer capacitors. ... 

The anode bodies of tantalum, aluminum, and most recently niobium capacitors are made of highly porous metals. These bodies are obtained either by sintering fine metal powders or electrochemical etching of thin foils. A thin dielectric layer is then electrochemically grown on the metal surface. Due to the porous structure of the anode bodies, the cathode polymer must be able to penetrate deep into the pores and coat aU internal surfaces in order to utilize the full, potential capacitance of the anode. 

Lampert and coworkers [36] have used a modified amorphous PEO-LiCFaSOs electrolyte for the realization of WO3 laminated windows using several types of counter-electrodes, such as niobium oxide, nickel oxide and a new class of solid redox polymerization electrodes [63]. These latter electrodes have an advantage over inorganic layers in that they can be tailored to the electrochromic material and ion specifically. Figure 8.18 illustrates the optical transmittance of a EW made of WOa/modified a-PEO/ion storage polymer [63]. 

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