О ВЛИЯНИИ НАПЯЖЕНИЯ, ВОЗНИКАЮЩЕГО ПРИ ПРЕ ЦИПИТАЦИИ, НА КОЭРЦИТ ИВНУЮ СИЛУ ФЕРРОМАГНЕТИКО В

, . - , m. . . , , , . , , Fe₃C .     

Beitrag zum problem der Exo-Emission von festkörpern

Zusammenfassung Es sind die Versuchsergebnisse des Studiums der Photoerscheinungen bei verschieden bearbeiteten Metallen (Au, Al, Pt) angeführt. Die Metallfolien wurden an der Luft mit UV-Licht bestrahlt und gleichmä\ig erwärmt. Die Ergebnisse wurden vom Gesichtspunkt der neueren Kenntnisse über Adsorption, Katalyse und Oxydation diskutiert. Daraus sind Folgerungen gezogen worden, die in manchen Fällen zu Bedenken über die Klärung der Exo-Emissions-Glow-Kurven zu führen scheinen.

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Au, Al, Pt . , . , . , .

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Ich möchte auch an dieser Stelle meinen besten Dank Frau K. Listoová aussprechen für die mit gro\er Sorgfältigkeit durchgeführten Versuchsreihen und K. Huml für die Hilfe bei der Bearbeitung der Versuchsergebnisse.     

The temperature dependence of the refractive index of germanium

The temperature dependence of the refractive index of germanium in a wave-length region of 1·8–5·5 and temperature region of 100–530 °K is given for three samples of single crystal germanium having different concentrations of impurities. The temperature dependence of the refractive index is non-linear. Our results are compared with those of other authors. An attempt is also made to theoretically interpret the observed dependence.

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1,8–5,5 100–530° K . . . , .

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In conclusion the author thanks Dr. Trousil from the Institute of Technical Physics, Czechoslovak Academy of Sciences, Prague, for supplying the germanium, Mr. Tma for preparing and polishing the prisms, Dr. Tauc from the same institute for enabling most of the measurements to be carried out in his laboratory, and Mrs. ilhavá for help in the measurements.     

Towards slow μ− production via muon catalyzed fusion

Slow ^– production via dd-CF using a two-layer arrangement is investigated. To determine its feasibility, experimental measurements are now in progress using the muonic X-ray detection method. The following experimental steps are being considered: (1) measurement of the number of ^– stopped inside a solid H₂/D₂ layer by detecting p K X-rays, (2) hot d emission detection by placing a secondary target at a distance of 10–30 mm from the layer and by detecting specific delayed X-rays, (3) measurement of the disappearance of d emission as the added D₂ layer is increased, (4) dd-CF measurement by detecting fusion protons, and (5) slow ^– emission detection. Results of the initial test experiment are presented.     

Anisotropy of the low temperature resistivity of hexagonal single crystalline spin glass systems

The impurity contribution to the resistivity in zero field (T) of dilute hexagonal single crystals of ZnMn, CdMn and MgMn has been studied in the mK range on samples cut parallel () and perpendicular () to thec-axis, using a SQUID technique for the measurements. Typical spin glass behavior is found in (T) as well as (T) for all alloys, with Kondo like logarithmic increases at higher temperatures and maxima atT _m at lower temperatures, indicating the influence of impurity interactions. The differences in the corresponding isotropic resistivity _poly(T) between the three systems can qualitatively be understood within the framework of a theoretical model by Larsen, describing (T) as a function of universal quantitiesT/T _K and _RKKY/T _K , where _RKKY is the RKKY-interaction strength andT _K the Kondo temperature. With respect to the two lattice directions studied, the behavior of (T and (T is anisotropic in the Kondo regime as well as in the range where ordering becomes important. While the anisotropy in the Kondo slope can be understood by an anisotropic unitarity limit, the understanding of the anisotropy in region where impurity interactions are important remains problematic.Dedicated to Prof. Dr. S. Methfessel on the occasion of his 60th birthday     

Photo-piezoelectric effect in semiconductors

A new photo-voltaic effect was observed which is caused by inhomogeneous distribution of the pressure in a semiconductor. Its production can be explained by the dependence of the energy gap on the pressure.

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, . .

     

Notes on the classical and the nonrelativistic limits in quantum mechanics

A method is presented which can be used to discuss both the classical and also the nonrelativistic limit of quantum mechanics. A one-to-one correspondence may be established between the asymptotic convergence of the resolvent and that of the timedependent solution. In so far as the question of dynamics is concerned we investigate the relation between families of nonrelativistic Hamiltonians and the corresponding Dirac-Hamiltonians when c± or when c±0. The nonrelativistic free theory formally shows the same pattern when ±0 (the classical limit) or when ±. The investigation finally shows how the asymptotic convergence of the relativistic theory can take place under some fairly general conditions of the radiation field.     

ДАЛЬНЕЙШИЕ ИССЛЕДОВ АНИЯ ФИЛЬТРА ДВОЙНОГ О ЛУЧЕПРЕЛОМЛЕНИЯ

, 4, (1954), 53. . .     

On the yellow colouring of lithium fluoride crystals

The paper deals with the causes of the yellow colouring of LiF crystals. In accordance with some other writers the authors arrived at the conclusion that colouring is caused by impurities. Selective absorption in the infra-red region at 2·8 is independent of this colouring. Analytical data were supplemented by crystal growing experiments in which defined admixtures of heavy metals, such as Co, Mn, Fe, Cr, Ni, Pt, Cu, were added to the melt. It is shown that, of the admixtures used, the most intense colouring is produced by manganese. Experiments on the effect of Cu and Pt were not entirely conclusive. In vacuum colour-producing impurities evaporate quite easily from the melt until their concentration drops below the critical limit required for colouring; in air this happens only if the charge is left in the melted state for a longer period (in our case a 1 kg charge was kept at 100°C above melting point for 36 hours). Results are improved if a dried gas, for instance nitrogen, is bubbled through the meit. A colourless crystal can be obtained in this manner even without using a vacuum; the starting material, however, must be sufficiently pure. A new method was worked out for preparing the salt by direct precipitation of LiCl and HF. Heavy metals are removed from the lithium component by means of cupral and dithizone. The construction of the apparatus used for the crystal growing experients in vacuum differs from that described in the appropriate literature.

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LiF

LiF. , . 2,8 . . , , , Mn, Fe, Cr, Ni, Pt, Cu. , . , . Pt . , , , ( : 1 kg-36 100° ). , , , . , , . LiCl HF. . , .

     

Деформация усика С ли нейной дислокацией

, , . : .

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The deformation of a whisker with edge dislocation

An approximate solution is given of the deformation of a plate caused by an edge dislocation lying in the central plane. The results are used to discuss the bending of a whisker as a result of an edge dislocation; in the calculations the whisker is approximated as an infinite band.

     

ВЛИЯНИЕ СТАРЕНИЯ НА Э ЛЕКТРИЧЕСКИЕ СВОЙСТ ВА ПОЛУПРОВОДНИКОВОЙ С ИСТЕМЫ Bi2Te3-Bi2Se3

, Bi₂Te₃-Bi₂Se₃. , , , . .

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Influence of ageing on change in electrical properties of semiconducting systems of Bi₂Te₃-Bi₂Se₃

The paper describes the effect of ageing observed on a semiconducting system Bi₂Te₃ — Bi₂Se₃. It is shown that the change in electrical conductivity and thermoelectric force, which takes place during ageing, is caused by the change in concentration of the free electrons. The influence of this process on the efficiency of equipment employing the Peltier effect is analyzed.

     

The van der Waals limit for classical systems

For a -dimensional system of particles with the two-body potentialq(r)+ ^v K(r) and density , it is proved under fairly weak conditions onq andK that the canonical pressure (, ) and chemical potential (, ) tend to definite limits when 0. The limiting functions are absolutely continuous and are given in terms of the derivative of the limiting free energy density which was found in Part I.     

ЭЛЕКТРОПРОВОД НОСТЬ И ТЕРМОЗЛЕКТРОДВИЖУ ЩАЯ СИЛА СЕРОГО ОЛОВА

, , , . .     

Exponential convergence to equilibrium for a class of random-walk models

We prove exponential convergence to equilibrium (L ² geometric ergodicity) for a random walk with inward drift on a sub-Cayley rooted tree. This randomwalk model generalizes a Monte Carlo algorithm for the self-avoiding walk proposed by Berretti and Sokal. If the number of vertices of levelN in the tree grows asC _N ~ ^N N ^–1 , we prove that the autocorrelation time satisfies N² N¹⁺     

Current distributions in a two-dimensional random-resistor network

The current and logarithm-of-the-current distributionsn(i) andn(ln i) on bond diluted two-dimensional random-resistor networks at the percolation threshold are studied by a modified transfer matrix method. Thek th moment (–9k8) of n(ln i) i.e., ln i&^k, is found to scale with the linear sizeL as (InL)^(k). The exponents (k) are not inconsistent with the recent theoretical prediction (k)=k, with deviations which may be attributed to severe finitesize effects. For small currents, ln n(y)–, yielding information on the threshold below which the multifractality of (i) breaks down. Our numerical results for the moments of the currents are consistent with other available results.     

The propagation of excitation energy in perturbed crystals

The process of the propagation of excitation energy in perturbed dielectric crystals with a weak bond between the atoms having zero permanent dipole moment is studied. It is shown that on certain assumptions this process of propagation can be regarded as the motion of a Frenkel exciton in the electrostatic field of the defect. Frenkel's exciton can be characterized in this case as a neutral polarizable particle having induced dipole moment equal to the change in the induced dipole moment of the crystal during the excitation of one of its atoms.

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, . , . .

     

Refining of CdSb and preparation of CdSb single crystals by zone melting

CdSb single crystals were prepared by zone melting in a boat both with and without a seed crystal in a stream of pure hydrogen or in a sealed and evacuated tube. The zone moved with a velocity of 1–20 cm/hour. Zone melting in an evacuated tube was used to prepare CdSb single crystals of high purity containing 10¹⁵ acceptors/cm³ at room temperature. During zone refining the stoichiometry is damaged; the front part of the ingot is enriched by cadmium and the end of the ingot by antimony; the enrichment is of an order of several percent after 10 passages of the zone. In the middle part of the ingot the stoichiometric compound remains unchanged. CdSb single crystals grow even by directional cooling of the melt of the stoichiometric compound without a seed crystal.

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CdSb CdSb

CdSb 1–20 cm/, . CdSb CdSb , 10¹⁵ cm³ . ; , . . . CdSb .

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The author died 28. 5. 1961.     

Прибор для измерения внутреннего затухан ия

. , E G. . .     

Experimental investigation of the nonlinear properties of the surface helical instability in germanium

The results of an experimental investigation of the parameters of the surface helical instability (SHI) in germanium are presented. The dependence of the amplitude of the current oscillations of the helical wave and frequency on the electric E and magnetic B fields with E and B significantly exceeding the threshold values E_t and B_t are presented for the case of nonequilibrium (for temperatures T < 343°K) and equilibrium (T 343°K) plasma. It is shown that for small supercriticality (_E = (E-E_t)/Et 1, = ( -_t)/_t 1) > the square of the amplitude of the current oscillations and the frequency shift are proportional to the supercriticality, i.e., the regime for excitation of SHI is soft.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 18–21, May, 1981.     

A study of the influence of the asymmetry of the Kα1 X-ray emission line of cobalt and copper on accurate measurements of lattice parameters

By accurate measurements of the lattice parameter of aluminium, silver and gold by K ₁ radiation of copper and cobalt it is proved that the values determined by the radiation of cobalt are systematically lower than those determined by the radiation of copper. A semiquantitative analysis of the influence of spectral asymmetry on the determination of the parameter from X-ray diffraction lines is carried out and it is proved that this influence is defined not only by the index of asymmetry of the emission line but also by the broadening of the corresponding diffraction line. From this analysis it follows that the differences in the parameter measured when using radiation of cobalt and copper, can be explained by the influence of the spectral asymmetry of the emission lines K ₁ of these radiations.

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₁

, K ₁ , , , . , , , . , , , K ₁.

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In conclusion the author thanks J. Bedná for careful measurement of the thermal expansion of the photographic film and advice when keeping the samples at constant temperature, J. ermák and J. Kratochvíl for numerous helpful remarks and J. Laek for preparing the samples of powdered gold.