Dopants and oxidants

Response times of undoped and Co-doped crystals for an incident intensity of 1 W/cm2 and a grating spacing of 0.7 pm are shown in Table 1. No systematic trend is apparent from these data, at least partially due to experimental uncertainties such as sample heating and variable reflection and absorption losses. Response times of as-grown and reduced Fe-, Mn-, and Cr-doped BaTi03 (18) range from 200 to 1200 ms under the same experimental conditions. Thus, it is clear that response times can vary considerably for crystals with different dopants and oxidation states. Additional experiments are needed to achieve better control over this key property. 

Highly transmissive, electroactive, and conductive poly[(3,4-alkylenedioxy)pyrrole-2,5-diyl] thin films were prepared by in situ chemical polymerization [36]. The process possesses a significant advantage as environmentally harmful organic solvents are not required since coatings can be obtained directly on the substrate. Many factors such as temperature, pH, nature of dopant, and oxidant were found to influence the film formation. PXDOPs were also synthesized from flexibly functionalized monomers, and showed highly stable aqueous compatibility and therefore unique potential for biomedical implications [37]. 

In this chapter, Lycra/Polyester fabric has been investigated— Pyrrole monomer purchased from sigma Aldrich chemical company, was distilled before use and was stored in a freezer— Naphtalene disulfonic acid (NDSA), ferric chloride were produced from Merck as an dopant and oxidant— Deionized water sulfuric acid from Merck, have been used. 

Chemical polymerization is carried out by mixing monomer, dopant, and oxidant in a suitable solvent. The chemical method enables the preparation of these polymers on a large scale without requiring special equipment. The polymerization of pyrrole proceeds through the formation of radical cations that couple to form oligomers which are further oxidized to form additional radical cations. 

These results indicate that the full picture of ionic transport in doped ceria is still not complete and that there are additional parameters in play, such as deviations from the assumption of randomly distributed dopants, which may be influenced by powder synthesis and processing. High-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and EELS investigations have revealed the existence of dopant-rich nano-sized domains in ceria doped with La, Sm, Y, Yb, Ho, Dy, Tb, and Gd. Ordering of oxygen vacancies was observed to take place in these domains. Clustering of dopants and oxide ion vacancies was also indicated by analysis of extended X-ray absorption fine structure (EXAES) measurements for Y- and... 

All materials will, to some degree, be subject to corrosion and oxidation by their environment, and the critical early stages of attack can often be understood through the use of surface analytical techniques. A similar approach is required to gain an understanding of the fundamental and applied aspects of surface catalysis, which is of great importance in the petrochemical industry. The microelectronics industry has also contributed to the development of modern surface analytical techniques, where there is a necessity to analyse dopant concentration profiles while retaining lateral resolution on the device of better than one micron. 

The process has been commercially implemented in Japan since 1977 [1] and a decade later in the U.S., Germany and Austria. The catalysts are based on a support material (titanium oxide in the anatase form), the active components (oxides of vanadium, tungsten and, in some cases, of molybdenum) and modifiers, dopants and additives to improve the performance, especially stability. The catalyst is then deposited over a structured support based on a ceramic or metallic honeycomb and plate-type structure on which a washcoat is then deposited. The honeycomb form usually is an extruded ceramic with the catalyst either incorporated throughout the stmcture (homogeneous) or coated on the substrate. In the plate geometry, the support material is generally coated with the catalyst. 

Bare CuOx-supported nanostructures showed some activity in H 2 production from methanol-water mixture under UV-visible irradiation [180]. Ni is also used as a dopant, and small amounts (1 wt.%) of this element in mesoporous titania guarantee good activity in water-methanol mixtures under UV-visible light [181]. Indium-tantalum oxide Ni-doped materials also provided photocatalysts with promising efficiencies for direct water splitting [182]. TiOz nanotubes doped with Ir and Co nanopartides were effective for visible light water splitting even in the absence of... 

The microstructure of commercial varistors is extremely complex, and commercial preparations also contain other dopants, mainly oxides of cobalt, manganese, chromium, and antimony, that are used to fine tune the varistor characteristics. The transition-metal dopants are chemically similar to Zn2+ and mainly form substitutional defects within the ZnO grains, such as CoZn, that modify the n-type behavior of the grain interior. (See also Chapter 8 for further discussion of the electronic... 

It has been noted that the conductivity and activation energy can be correlated with the ionic radius of the dopant ions, with a minimum in activation energy occurring for those dopants whose radius most closely matches that of Ce4+. Kilner et al. [83] suggested that it would be more appropriate to evaluate the relative ion mismatch of dopant and host by comparing the cubic lattice parameter of the relevant rare-earth oxide. Kim [84] extended this approach by a systematic analysis of the effect of dopant ionic radius upon the relevant host lattice and gave the following empirical relation between the lattice constant of doped-ceria solid solutions and the ionic radius of the dopants. 

A higher efficiency, yet simpler structure PPLED device fabricated with the same dopant and host materials was almost simultaneously reported by Yang and Tsutsui [35]. The highest EQE of their device ITO/PVK 5%Ir(ppy)3 /OXD-7/Mg Ag (where ITO is indium tin oxide) (using OXD-7 (7) as an electron-transporting layer (ETL), Chart 4.3) reached the value of 7.5%, which was the first reported PLED with external efficiency above 5%, an upper limit of the fluorescent PLEDs. The power efficiency was 5.8 lm/W at the luminance of 106 cd/m2. 

The materials used as up-converters consist of a rigid host lattice with rare earth dopants. Fluorides and oxides have been used as host lattices, the latter being slightly... 

It has been suggested [497] that if oxide cathodes are doped with the oxide of the metal present in solution as an impurity, the electrodes become immune with respect to that specific impurity. Such a homeopathic approach is certainly intriguing, but it should be documented with some more evidence that clarifies the state of the dopant and its role during impurity adsorption. 

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