Cerium charge distribution

Perhaps the earliest system to be described as an Anderson transition was cerium sulphide (Cutler and Mott (1969), on the basis of observations by Cutler and Leavy (1964)). The material in question can be written Ce3 xvxS4, where v is a cerium vacancy, the vacancies being distributed at random. The field near a cerium vacancy repels electrons, because they are negatively charged. Variation of x, then, changes the number of electrons and the number of scatterers. Figure 1.25 shows some results on the conductivity. At that time the present author believed... 

The extraction ability of neutral organophosphorus compounds closely related to the charge density of phosphoryl oxygen (qo) and phosphorus atom(qp). It was found that the distribution ratio of cerium enhanced as the qo and qp values was increased. Meanwhile a linear free energy relationship exists between the 2A.i values and the Kabachnik constant for substituents of phosphorus compounds. As estimated by least squares method, an empirical equation v° =-3.84+0.1682Ai was deduced... 

The differences between the actinide and lanthanide metals can be rationalized by a consideration of the differences between the 4f- and 5f-electron shells [25]. In the 4f series, all the 4f electrons (added after cerium) are buried in the interior of the electron cloud. The 4f electrons are thus confined to the core of the atom, and experience relatively little interaction with electrons in the 5d shell. The maxima in the radial charge density occur well inside the usual interatomic distances in solids, and consequently the 4f electron properties of the free atoms are retained in the metallic as well as ionic lanthanide solids. Cerium is the only 4f metal that does not conform to this generalization, presumably because its 4f-electron shell is not yet fully stabilized. The actinide 5f electrons behave quite differently. For the early members of the actinide series, the Sf electrons have a greater radial distribution than do their 4f homologs. The first few 5f electrons are not confined to the core of the atom, and they can therefore interact or mix with the other valence electrons to affect interatomic interactions in the solid state. Beyond plutonium, all the 5f electrons are localized within the atomic core, and the resemblance between the f-block elements becomes closer. Americium is the first actinide metal whose crystal structure resembles that of the lanthanide metals. In the transcurium metals, the resemblance to the lanthanide metals becomes increasingly stronger. The room-temperature crystal structure for the elements for Am to Cf is dhep, just as it is in the light lanthanides. 

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