Addition of dopant

However, in the case of the perovskite even the application of sintering temperatures as high as 1200 °C did not result in a higher overall ionic conductivity. Since the total ionic conductivity is two orders of magnitude lower than the bulk conductivity in polycrystalline Li0 34La05] Ti 0294, an improvement by way of the preparation route is necessary rather than changes in the lattice by the addition of dopants,... 

The addition of dopants is found to have beneficial effects. However, they are not restricted only to transition metals. The hydrogenation of acrylic acid can be promoted significantly by the addition of neodymium ions onto the palladium particles [142], The selective transformation of 3,4-dichloronitrobenzene to the corresponding aniline has been selected to test pre-prepared Pt hydrosols as heterogeneous catalyst precursors (see Figure 3.9) [143],... 

An efficient, low temperature oxidation catalyst was developed based on highly disperse metal catalyst on nanostructured Ti02 support. Addition of dopants inhibits metal sintering and prevents catalyst deactivation. The nanostructured catalyst was formulated to tolerate common poisons found in environments such as halogen- and sulfur-containing compounds. The nanocatalyst is capable of oxidizing carbon monoxide and common VOCs to carbon dioxide and water at near ambient temperatures (25-50 °C). 

When heated, polyvinyl chloride (PVC) and polyvinyl alcohol (PVA) lose HC1 and H20, respectively, to produce dark-colored conductive polyacetylene. Superior polymers of acetylene can be made by the polymerization of acetylene with Ziegler-Natta catalysts. The conductivity of polyacetylene is increased by the addition of dopants, such as arsenic pentafluoride or sodium naphthenide. 

Semiconductor band edge energetics manipulation of the band edges by solution pH or the addition of dopants to the particle matrix allows for the tailoring of the photogenerated electron energetics to specific actinide reductions. 

Fig. S.S. The change in deposition rate with the addition of dopants (diborane and phosphine) in compensated a-Si H (Street et at. 1981).

Another study examined the NH3 and CO2 adsorption heats on several zirconia catalysts, differing in their preparation procedure and/or in the addition of dopants [46]. The differential heats of NH3 and CO2 adsorption show a wide range of variability, displaying either a plateau of constant heat or a continuous decrease indicative of adsorption heterogeneity [12]. The ratio between the number of the basic and acidic sites, Ub/ua, was calculated for each catalyst from the microcalorimetry results, by dividing the amount of adsorbed CO2 by the amount of adsorbed NH3. These catalysts were used to produce alk-l-ene from 4-methylpentan-2-ol. Alk-1-ene selectivity was found to first increase with the b/Wa ratio, reach a maximum and then decrease, whereas ketone formation continuously increased, being negligible for low Ub/ua values. 

Unmodified Pb(Zr, Ti)03 ceramics are seldom used. The dielectric and electromechanical properties are tailored to a particular device requirement by changing the Zr/Ti ratio and by addition of dopants or modifying agents. Thousands of these formulations have been documented, and some of the more important are summarized. 

At rather drastic conditions of 24h/l 100 C two of the products still maintain a surface area of approx. 60 rxi/g - this can be an important feature for high temperature application making the addition of dopants superfluous. 

Numerous Br SSNMR studies have been carried out on AgBr, many of which focused on the addition of dopants and their effects on the bromine SSNMR spectra (see below).The temperature and time dependence of the Br NMR signal of plastically deformed AgBr (both pure and NaBr doped) have also been discussed and related to the density of lattice dislocations. The reader is referred to Table 9 for additional information on AgBr. 

This section draws attention to some of the common structure types adopted by semiconductors. The diamond-type network (often referred to an adamantine solid structure) is adopted by Si and Ge the addition of dopants occurs without structural change. Related to this network is the zinc blende lattice and among compounds adopting this structure are GaAs, InAs, GaP, ZnSe, ZnTe, CdS, CdSe,... 

Intrinsic defects occur in lattices of pure compounds extrinsic defects result from the addition of dopants. 

The manufacture of heterogeneous catalysts from pre-prepared nanometal colloids as precursors via the so-called precursor concept ll has attracted industrial inter-est.l l An obvious advantage of the new mode of preparation compared with the conventional salt-impregnation method is that both the size and the composition of the colloidal metal precursors can be tailored for special applications independently of the support. In addition, the metal particle surface can be modified by lipophilic or hydrophilic protective shells, and covered with intermediate layers, e.g. of oxide. The addition of dopants to the precursor is also possible. The second step of the manufacture of the catalyst consists in the simple adsorption of the pre-prepared particles by dipping the supports into organic or aqueous precursor solutions at ambient temperature. This has been demonstrated, e.g., for charcoal, various oxidic support materials, even low-surface materials such as quartz, sapphire, and highly oriented pyrolytic graphite. A subsequent calcination step is not required (see Fig. 1). 

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