Relative change of the electron density at the Cu nucleus in Cu-Ag alloys

The decay constant of⁶⁴Cu in Cu–Ag solid solutions has been measured at various Cu concentrations. Deduced values of the relative changes of electron densities (0)/(0) at the Cu nucleus are given. The observed concentration dependence of (0)/(0) is discussed in terms of a volume effect and charge transfer from Cu to Ag.     

Relative change of the electron density at the Cu nucleus in CuSCN and Cu(SCN)2

The change of the decay constant of⁶⁴Cu in CuSCN and Cu(SCN)₂ compared to metallic Cu has been measured. Values of the relative change of the electron density at the Cu nucleus are deduced taking condensed matter effects on overlap and exchange corrections into account.     

Effect of chemical structure on the electron density at the iodine nucleus

Theoretical estimates of the electron density at the I nucleus in some compounds provide a basis for a systematic consideration of pertinent properties (EC, IC, Mössbauer IS). This paper presents an advanced version of such a systematics which has been extended by including a qualitatively new case (ICl ₄ ^– ) and by remeasuring the chemically induced EC variation of¹²⁵I. The corrections such as for binding-energy variations and for the effect of exchange and overlap were found to be less important here than one would expect from literature.     

Effect of chemical structure on the electron density at the tellurium nucleus

This paper reports results of a study in which the Xα-SW method is employed to deduce estimates of the differences in the electron densities at the Te nucleus in some compounds. On the basis of these estimates some assertions are deduced to the calibration problem of the Mössbauer nuclide¹²⁵Te and to the chemical influence on the IC of the 35.5 keV M1+E2 transition in¹²⁵Te.     

Electron density and electron redistribution in alloys—II: Electron density in alloys and intermetallic phases

Electron density for alloys which have close-packed metallic structures is calculated by assigning valence electrons to octahedral and tetrahedral interstices, a method which has been previously used for elemental metals. Some localization of electron density is proposed for β -phases when there is considerable difference in ion core sizes. This method of characterizing electron density in alloys can be used to derive structures with the amount of electron transfer if an assumption is made for the volume fraction occupied by each component of the alloy. In general, the electronic structure of intermetallic phases appears to be dominated by the correspondence of a definite number of valence electrons with the number of interstices in the metallic structure (the Hume-Rothery $\text{e}\text{a}$ ratios). The model used can also accommodate electron distributions which include both ionic and covalent components of electron density. This is the case for Laves phases and the metallic A-15 compounds. There is a preponderance of intermetallic phases where one component is a d-shell metal. Evidence is presented that in several such alloys there is a change in d-shell configuration of the elemental metal which serves to minimize size differences of the ion cores of the alloy.     

飞秒激光成丝诱导Cu等离子体的温度和电子密度

研究了飞秒激光成丝诱导铜击穿光谱,利用光发射光谱对产生的铜等离子体光谱强度沿着丝长度进行了测量,获得了在不同样品与聚焦透镜间距离的Cu(I)的强度分布.结果显示,由于强度钳箍效应成丝诱导的光谱在较大的透镜样品间距离范围内有较强的辐射强度.另外,利用玻尔兹曼图和斯塔克展宽计算了整个成丝繁衍距离中Cu等离子体温度和电子密度.     

Relation between internal conversion coefficient and electron density at the nucleus for spin polarized Fe electrons

An ICC computation for the 14.4 keV transition in⁵⁷Fe has been made using relativistic wavefunctions derived from spin polarized UHF wave functions of atomic iron. It is shown that ICC and electron density at the nucleus are proportional for polarized s electrons as has been found already for unpolarized electrons.     

Ground state of alloys by the method of the electron density functional

An expression for the total energy of an alloy with an arbitrary degree of long-range order is written within the framework of the method of the electron-density functional. A method is proposed for calculation of the Coulomb, kinetic, and exchange-correlation energies. The ground state of the alloys Na-Li and Rb-K is investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 35–41, November, 1978.     

Electrical resistivity and electron state density in binary iron alloys

An expression is derived for the phonon component of electrical resistivity using a four-band model which considers the electron contribution to conductivity from two 4s subbands and the hole contribution from two 3d subbands with differently oriented spins, using Mott's concepts in the relaxation time approximation. The expression obtained gives the dependence of resistivity upon electron state density at the Fermi level. The concentration dependence of resistivity is calculated for alloys of iron with chromium, manganese, cobalt, and nickel.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 7–12, April, 1979.     

Electron density and electron redistribution in alloys—I: Electron density in elemental metals

The changes in electronic structure around each metal atom in an alloy are more accurately described in terms of electron redistribution than electron transfer. The important elements in a model for such electron redistribution are the electron configuration and radius of the positive ion cores and the conduction electron density and its variation in the interstitial regions. Positive ion core radii for metals are derived from an empirical relation between ion core radii and intermetallic distance with electronic configurations of the core from positron annihilation data. These derived ion core radii are in good agreement with those calculated for metal electron densities by Welch and Lynn from Hartree-Fock wave functions. Average conduction electron densities can be directly calculated from these radii and the experimental atomic volume; the variation of conduction electron density in the interstitial region is calculated by assigning electrons to octahedral and tetrahedral interstices according to the Interstitial Electron Model. The calculated electron densities and the interstitial variation agree very well with the experimental electron densities of Be as determined from X-ray diffraction data as well as with calculated electron densities for Na, Mg and Al. Ion core configurations are compared with those derived from band theory and also those of the Engle-Brewer Correlation and the Samsonov-Pryadkov-Pryadkov Configurational Model.     

Observation of surface segregation of sulphur in CuNi alloys at elevated temperature with scanning Auger electron microscope

Surface segregations of Cu and S in a CuNi (50wt%) alloy at elevated temperatures of ～600°C were studied under scanning Auger electron microscope, JAMP-3. Scanning images of S, Cu and Ni Auger signals have revealed that the surface segregations of both Cu and S take place preferentially depending on grains and the contrasts in S and Cu Auger images are complementary. This leads to another confirmation of the previous work, namely, that the surface segregation of Cu is considerably suppressed by the existence of S at the outermost atom layer.     

Inequalities of the electron density at the nucleus and radial expectation values of the ground state for the lithium isoelectronic sequence

The electron density at the nucleus, ρ(0), and the radial expectation values, (-2≤n≤10), of the ground state for the lithium isoelectronic sequence are calculated with a full core plus correlation (FCPC) wavefunctions. By using these obtained expectation values, the accurate inequalities of the electron density at the nucleus and the radial expectation values derived by Gálvez and Porras for these systems are examined and verified. The final results show that FCPC wavefunctions used in this work can give satisfactory results in full configuration space.     

Cellular approximation of the method of the model electron density functional. Disordered alloys

An expression is obtained, by the method of cells, for the total energy of metals and disordered binary alloys that is accurate up to first order in the deviation of the densities of almost free electrons from their average values. The use of the average values of the electron densities over the Wigner-Seitz cells makes it possible to eliminate the specific form of the interaction potential of almost free electrons with the core and valence d and f electrons and to determine their integral effect in terms of the equilibrium properties of pure metals.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 71–76, May, 1991.     

Neutron investigation of collective excitations in liquid K-Cs alloys: the role of the electron density

The investigation of the ion dynamics in the liquid alloy K52Cs48, which has the same electron density as Rb, was carried out by neutron inelastic scattering. Well defined collective excitations were observed up to the maximum value of momentum transfer of the experiment. A scaling of the dispersion relation data was found to hold between K-Cs alloys, Rb and Cs. The suggested scaling points out the key role of the conduction electron density in the collective dynamics of alkali metals.     

Multiparticle interatiomic interaction potentials for alloys using the model electron density functional method

A method for calculating multiparticle interatomic interaction potentials for binary alloys within the framework of a model electron density functional is presented. An expression for the total ground state energy of metals and alloys is obtained. It is shown that in simplicity of the computational scheme and speed of computation, this approach does not yield to the method of inserted atoms, but has a more rigorous physical basis in comparison with the latter.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 90–99, April, 1996.     

Long-period incommensurate superstructures in Cu-Au alloys: Relation with short-period ordering

The nature of the stability of incommensurate long-period structures in alloys of the system Cu-Au is investigated on the basis of first-principles calculations of the electronic structure. It is shown that many structural properties of such formations can be explained only if the latter are treated as superstructures with respect to ordinary superstructures (L1₂ or L1₀): the electron spectrum of the superstructure and not that of the initial disordered alloy must serve as the initial spectrum. The observed dependence of the long period N on the degree η ?of the “short” long-range order is explained. The reasons why two-dimensional long-period superstructures from in the alloy Au₃Cu are found. Arguments supporting the fact that among quasicrystalline substances long-period superstructures fall between incommensurate systems and quasicrystals are presented.