Oxidative dopants

The thermistor material is usually a metal oxide, eg, manganese oxide. Dopants, eg, nickel oxide or copper oxide, may be added to obtain a variety of resistance and slope characteristics. The material is usually skitered kito a disk or bead with kitegral or attached connecting wkes. Figure 4 shows a typical series of steps ki the production of a disk thermistor. 

For a simple solid solution the lattice parameter usually follow Vegard s rule with good approximation, i.e. a linear relationship exists between lattice parameter and the concentration of the solute. The slope of this straight line is termed Vegard s slope, Kim published an empirical relation between ionic radius of the metal ion of oxides (dopants) dissolved in ceria (and other fluorite structured oxides)... 

V. During over-oxidation, dopant molecules [L- or D-aspartlc acid) were de-doped from the polymeric network. Benzidine was... 

Warren, L.R, and D.R. Strauss. 1989. Chemical synthesis of conducting polypyrrole using uniform oxidant/dopant reagents. US Patent 4,847,115. 

As, with the exception of the mentioned oxidized compounds, the metallomacrocycles do not crystallize forming columnar quasi-one-dimensional structures, one of the prerequisites for conductivity is not met. In addition the stacking repeat distances and the donor-acceptor distances in doped compounds cannot be controlled in any way. By using oxidizing dopants other than halogens, e.g. quinones, integrated stacks can be formed leading to insulators. 

INDIUM OXIDE. In20j. Mol. wt. 277.64 sp. gr. 7.179 m.p. 1910°C. An n-type semiconductor finding use as a resistive element in integrated circuits. Resistivity values from 100 ohm/sq to megohms per square can he tailored. The screen printed mix consists of high-purity indium oxide, dopants and borosihcate glass flux. Piling temperature 900-1000°C. Temperature coefficients of resistivity of such systems have been measured at <500 ppm/C from room temperature to 100°C. 

The reference electrode of these oxygen sensors consists of a platinum electrode in a reference gas with defined oxygen partial pressure, which is separated fi om the melt by a wall of doped zirconia solid electrolyte with unit oxide transport number. Yttria (Y2O3) is used as the second oxide (dopant), which renders the doped oxide solid electrolyte more stable than calcium oxide (CaO) and magnesium oxide (MgO), which have also been tried as the second component of the doped ceramic but were found rather unsatisfactory. Practical units applied in laboratory and industrial glass melts consist of a combination of the essential (platinum) electrode and the zirconia electrolyte, which are constmcted for easy handling. These units are called... 

The formation of a very thin EU2O3 film at the grain s surface appears by XPS while Rietveld analysis reveals a global loss of Eu in the phosphor s structure, but for charge equilibrium reasons, 2/3 of the oxidized dopant Eu ions remain in the interslabs of the BAM matrix, mostly in the nmO... 

For P(Py) and P(3AT), combination oxidant/dopants such as FeCla and CUBF4 (this in acetonitrile as well as aqueous medium), or oxidants such as ferricyanide may be used under similar reaction conditions. The polymers so obtained have conductivities equal or superior to those from electrochemical syntheses. Control of morphology, conductivity, doping, and related factors is however a little more difficult in chemical polymerizations, with slight changes in temperature, concentration and other factors yielding substantial differences in polymer properties, and even identical synthetic procedures never yielding exactly the same polymer each time. 

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