Solids doping

There are several ways in which a solid doped with an aliovalent impurity can maintain charge balance. It is by no means simple to be sure which compensation mechanism will hold, or even if one mechanism will hold over all of the doping range. However, there are some quantitative guidelines that apply, especially for oxides. The principal mechanism will depend upon how easily the host cation that is being replaced is oxidized or reduced. 

An interesting aspect related to the design of these ensembles is the fine-tuning of the polarity of the inner pores. In this respect, Inumaru et al. reported the adsorption behavior of alkylphenols and alkylanilines by MCM-41 -type solids doped with different degrees of Al3+ and equipped with alkyl chains of different length grafted onto the surface.24,25 The authors found two well defined trends (1) lipophilic guests were... 

Dopant atoms chemical impurities that are deliberately introduced into the semiconductor lattice to provide control over the conductivity and Fermi level of the solid Doping the introduction of specific chemical impurities into a semiconductor lattice to control the conductivity and the Fermi level of the semiconductor Effective density of states the number of electronic states within ikT of the edge of an energy band, where k is the Boltzmann constant and T is the temperature Energy bands a cluster of orbitals in which the individual molecular orbitals are packed closely together to form an almost continuous distribution of energy levels... 

This section describes how solid doping sources are obtained by means of periodic grouping. 

Particularly, a synergism between cesium hydrogenophosphate and samarium phosphate has been observed for the O-alkylation of dihydroxy-benzene (ref. 2). We described in this paper some characterizations of this solid doped or not, that may allow to explain catalytic results. 

Dopant atoms chemical impurities that are deliberately introduced into the semiconductor lattice to provide control over the conductivity and Fermi level of the solid Doping the introduction of specific chemical impurities into a semiconductor lattice to control the conductivity and the Fermi level of the semiconductor... 

Relativistic Ab Initio Model Potential embedded cluster calculations on the structure and spectroscopy of local defects created by actinide impurity ions in solid hosts are the focus of attention here. They are molecular like calculations which include host embedding effects and electron correlation effects, but also scalar and spin-orbit coupling relativistic effects, all of them compulsory for a detailed understanding of the large manifolds of states of the 5f" the 5f" 6d configurations. The results are aimed at showing the potentiality of Relativistic Quantum Chemistry as a tool for prediction and interpretation in the field of solids doped with heavy element impurities. 

The most successful solid-state optical refrigeration results to date have been achieved using solids doped with tripositive lanthanide (Ln ) ions. The 4f shell is only partially filled along the series from Ce to giving rise to electron... 

Following the initial experiments by Kaiser, Axe (1964) extended the theories of Judd (1962) and Ofelt (1962) to calculate selection rules and intensities of two-photon transitions in solids doped with lanthanides. The theoretical predictions with later extensions by Bader and Gold (1968) laid largely untested as an hiatus occurred in the experimental studies in this area, the emphasis having shifted in this period to the observation of (4f) states buried in allowed (5d) or conduction bands. Interest has since returned following the work of Degenais (1981), Downer et al. (1982) and Down and Bivas (1983) on Gd " in LaFj. As noted in fig. 20, these workers observed a number of violations of the selection rules developed by Axe in both the intensity and polarization dependence and were able to trace the descrepancies to various approximations necessary in the... 

See also -> f-alumina, -r BIMEVOX, bismuth oxide, - cerium dioxide, conducting solids, -> defects in solids, - diffusion coefficient (- determination in solids), - doping, electrochemical gas compressor, -> electrolytic permeability, electronic defects, - four-... 

Braun [22] extended Onsager s theory to the case that the dissociating e-h pair is the lowest excited state of the system, such as the charge transfer (CT) state in a binary molecular solid, for instance a charge transfer crystal composed by donor-acceptor moieties or a molecular solid doped with either donors or acceptors. The essential new element in Braun s theory is the notion that the e-h pair has a finite lifetime, determined by its nonradiative decay. This implies that an initially optically... 

---