摘要:

AbstractThe atom by atom growing of the energetically most favourable lithium clusters of 2 to 10 atoms was studied. The clusters had the structure of a body centered cubic lattice of lithium. The LCAO–HMO method was used for the energetic description of the clusters. It was assumed that there is an interaction of a given atom with its neighbours in the first six coordination spheres in the lithium lattice. All possible (two‐dimensional and three‐dimensional) positions of then+ 1statom with respect to a cluster ofnatoms were taken into account. It was shown that from 2 to 10 atoms the cluster grows twodimensionally and has the geometry of the lattice plane with the highest net density in the body centered cubic lattice of lithium, the 110 lattice plane. This was discussed in detail. It was shown that the bond energy per atom increases, whereas the energy of a bond between nearest neighbours decreases with increasing number of atoms in the cl

ISSN:0023-4753    

DOI:10.1002/crat.19750100602

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractDie A7‐Struktur der Elemente der Gruppe Vb des Periodensystems ist mit charakteristischen halbmetallischen Eigenschaften verbunden. Unter Einwirkung von äußerem Druck werden diese Elemente dagegen halbleitend. Von den AIV‐BVI‐Halbleitern (ebenfalls mittlere Valenzelektronenkonzentration 5) ist dagegen bekannt, daß die Strukturparameter Rhomboederwinkel αr= 60° und „innere Koordinate”︁u= 0,250 sind. Es wird nun mit Hilfe von Röntgenbeugungsexperimenten gezeigt, daß für Wismut in einem breiten Druckbereich die stabile halbleitende Phase in den Intervallen 60°0,250, i

ISSN:0023-4753    

DOI:10.1002/crat.19750100603

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractKRUPKOWSKI'Sexpression of activity coefficients has been applied to the liquid binary mixed phase of Ga–P. An interaction parameter of α = 1909 – 4.107Tand an asymmetry coefficient ofm= 1.448 were determined from liquidus data and an entropy of fusion of GaP of 16.8 e.u. per mole at 1743 K. The activity coefficient of phosphorus along the liquidus curve shows a minimum atxP= 0.032. There is an excellent agreement between calculated and experimental activities and vapour pressures over the whole controllable range of concentrations of the liquid phase. A total phosphorus pressure of 30.8 atms was calculated for the melting point of

ISSN:0023-4753    

DOI:10.1002/crat.19750100604

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractA calorimetric method was applied for the determination of crystallization kinetics of vibrationally mixed suspensions of Na2SO4· 10 H2O and Na2CO3· 10 H2O at 25°C with supersaturations up to 0.083 and 0.119 g hydrate/g free water, resp. The characteristic dimension of crystals was 0.125–0.6

ISSN:0023-4753    

DOI:10.1002/crat.19750100605

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe precipitation of magnesium, calcium, strontium and barium oxalates and of manganous, ferrous, cobalt, nickel and copper oxalates was studied from equivalent aqueous solutions at 22°C: the initial overall concentrations (C) generally varied from 0.001 to 0.2 M and the saturation ratios (Smox) varied fromNi; that is, generally in the order of increasing M++–Ox−and M++–MOx2−bond strengths and increasing surface energies of the metal oxalate crystals.Induction periods decreased with increasing‐concentration and saturation ratio; overThe factorstC1andtS1depended in turn on the ‘rate constants’ for nucleation and growth during the induction periods and

ISSN:0023-4753    

DOI:10.1002/crat.19750100606

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe present paper reports on the results of an investigation of crystallization of multilayer structures with a narrow‐gap semiconductor surrounded by two wide‐gap ones in the Al‐Ga‐P‐As system on GaAs and GaP substrates. Influence of the lattice parameters' difference on the value of thermal stress in structures with a composition gradient was determined by the bend of structures separated from the substrate. It has been proved that with the P concentration in solid solutions being less than 1% heterojunctions with less tensions than in the Al–Ga–As system are available. A new method of obtaining AlxGa1–xPyAs1–ysolid solutions with the concentration of P proportional to that of Al has been worked out on the basis of which multilayer heterolight‐emitting structures

ISSN:0023-4753    

DOI:10.1002/crat.19750100607

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractMethods of prospective evaluation of the use of various materials as active elements for quantum generators for certain applications are considered. The way of evaluation for all kinds of dielectric crystal lasers with respect to optical quantum generators, applicable in technical designs is given. The influence of material properties on the prospective technical use is considered. The results are summarily analyzed.

ISSN:0023-4753    

DOI:10.1002/crat.19750100608

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractMathematical modelling methods are considered for the evaluation of perspective use of various materials, dielectric crystals as matrices for laser elements of a certain application. Garnet structure crystals and perovskite structure crystals on the basis of mixed oxides of elements of the Third Group of the Periodic System are considered in detail. The determining influence of crystal‐chemical aspects on the crystal quality and its further application is defined. On the basis of calculations a certain advantage of perovskite structure crystals (aluminate and scandates of rare earths) of garnets during their application as matrices for active elements of optical quantum generators is deduced. A possibility of creating laser elements on the basis of solid solutions of perovskite structure combinations is emphasize

ISSN:0023-4753    

DOI:10.1002/crat.19750100609

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe paper is concerned with theoretical models of dislocation segments fixed at their ends to local obstacles of either the same or two different types. The dislocation inertial properties are shown to influence substantially the probability of unpinning from the local obstacles as the crystal is subjected to ultrasonic oscillations. The unpinning probability in the presence of oscillations can be much higher than that with a constant load of the same magnitude. In the case of two types of obstacles, the weaker can play a “provocative” role facilitating unpinning of dislocations from the stronger obstacles. The considered effects constitute admittedly one of microscopic mechanisms of the plasticizing and “softening” action of ult

ISSN:0023-4753    

DOI:10.1002/crat.19750100610

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractDurch Analyse der Temperaturabhängigkeit des Hallkoeffizienten konnten für p‐ZnSiAs2‐Kristalle die effektive Zustandsdichtemasse des Valenzbandes sowie Störstellenparameter bestimmt werden. Die effektive Zustandsdichtemasse der Löcher beträgt in ZnSiAs2(0,21 ± 0,03)m0. Es wurden drei Akzeptorniveaus gefunden, die 15 meV, 40 meV und 200 meV oberhalb der Valenzbandkante liegen. Unter Berücksichtigung der Wechselwirkung der Ladungsträger mit der großen Zahl der longitudinalen Phononenzweige, die in Chalkopyritkristallen auftreten, wurde eine Beweglichkeitsanalyse durchgeführt. Die Übereinstimmung zwischen experimentellen und theoretischen Beweglichkeitswerten ist im Temperaturbereich von 77 K

ISSN:0023-4753    

DOI:10.1002/crat.19750100611

出版商:WILEY‐VCH Verlag    

年代:1975

数据来源: WILEY