Abweichungen von der Gleichgewichtsbesetzung der Ar-II-Terme in einem an der Oberfläche von Ferrelektrika erzeugten Plasma

A plasma obtained in argon near the surface of ferroelectric BaTiO₃ ceramics has been examined in this work. It was found that the population densities of the excited Ar II doublet levels are greater than those of the excited Ar II quartet levels. This fact is related to the specific conditions of argon atoms excitation in the electric field of the ferroelectric domains. There is a possibility of ionization with simultaneous excitation of the neutral argon atoms.     

Die Abweichungen von den Cauchy-Relationen

Qualitative rules for the deviations from the Cauchy relations are derived from experimental data. These departures are the components of a second rank tensor. The coefficients of “lateral interaction”c _iijj dominate in most cases over the correspondent shear resistancesc _ijij. Extreme effects of this type are generated by asymmetric lattice particles. Covalent bonds and other strong bonds with preferential orientation as well as strong overlap cause opposite effects. The departures from the Cauchy relations and the atomistic binding properties are very closely correlated.     

Bilanzierung der Ozonsynthese im nichtthermischen Plasma

A simple model of a non-thermal oxygen plasma is used to calculate the ozon concentration as a function of the plasma parameters pressure, gas and electron temperature and electron concentration. In particular it is shown that the ozon yield depends strongly on the electron temperature and concentration except for certain intervals of parameters where a distinct plateau exists and the ozon concentration reaches its maximum value.     

Beobachtungen von Diffusionsprozessen im Schichtensystem Silber-Zinksulfid mit dem Photoemissions-Elektronenmikroskop

By means of the photoemission electron microscope Balzers Metioscope KE 3 the diffusion processes were investigated which occur at elevated temperatures in a system of silver and zincsulfide coatings. At 150 °C the formation of Ag₂S at the surface of the silver film can be seen (high emitting round spots on bright background) and at 240 °C one can observe the diffusion of silver through the zincsulfide film (high emitting small spots on dark background). On heating coagulation process of the silver particles takes place in the boundary zone near the silver layer. With increasing temperatures the mobility of these particles becames high enough to allow them to migrate into the silver layer.     

Optimierung von mikrobiologischen Stoffwandlungen. Zusammenhang zwischen der Geschwindigkeit der Zellreproduktion und dem thermodynamischen Wirkungsgrad mit dem Ziel der Optimierung von mikrobiologischen Stoffwandlungen

Relationship between Thermodynamic Efficiency and Rate of Microbial Growth Aimed at Optimization of Microbial Growth The relationship between thermodynamic efficiency and rate of microbial growth has been deduced using linear nonequilibrium thermodynamics and kinetics. The optimum rate of microbial growth follows as a result.     

Untersuchung der Elektronenkomponente von Einzellawinen mit dem Photomultiplier

With a photomultiplier single electron avalanches of 10³ carriers can be observed in nitrogen. 2.5% of all photons (in the range 3000≦λ≦7000 Å) of an avalanche produce a photoelectron at the cathode of the photomultiplier. The influence of the variable solid angle on the photomultiplier pulse is given. Trouble by noise is calculated and it is shown that the information depends on the number of photoelectrons only. The electron components of avalanches in methane, nitrogen, and mixtures have an exponential rise and the measured rise time constant τ_beob is in accordance with the theoretical value 1/αυ_. For carrier numbers >10⁶ space charge influence is observed, as given by theory. The quantum efficiencyQ per ionizing impact is found to beQ～10^?3 in vapours andQ～1 in gases. Values of the electron drift velocity in mixtures of N₂ and CH₄ are given.     

Entmischung von Isotopen im Bereich der Dissoziation

Regarding the dissociation energies of isotopes to be equal, the mass separation of two isotopes along the gradient of temperature in the region of dissociation is treated theoretically. In this system there seems to be a disagreement: The separation effect does not vanish, when corresponding particles are identified. An explanation is given for this observation.     

Der Zusammenhang der Rechteckigkeit der Hystereseschleife von Mangan-Magnesium-Ferriten mit dem inneren Entmagnetisierungsfaktor

Ohne Zusammenfassung

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Das magnetische Verhalten von FeGe2-Einkristallen,auch für Abweichungen von der stöchiometrischen Zusammensetzung

Tetragonal stoichiometric pure FeGe₂ single crystals are para- or antiferro-magnetic with an isotropic mass susceptibilityε ₃₀₀=6.5·10^?6 cgs _m and Δ(1/χ)/ΔT=150 between 90 and 435 °K. Deviations from the stoichiometry give on the germaniumside a corresponding decrease ofχ. Excess iron risesχ and aboveΔFe=+2% a drastic field- and temperature-dependence ofχ sets in. Crystals with nonstoichiometric overall composition (by chemical analysis) are made up of two phases: In a matrix of pure FeGe₂ precipitates lie parallel to thec-axis, as revealed by polishing and etching. This behaviour explains that Mössbauer experiments give no variation of the Néel point with composition. The precipitates make the iron rich crystals magnetically anisotropic.     

Untersuchungen im Anfangsbereich der Verformungskurve von Eisen-Einkristallen

The stress-strain curves of iron single crystals at room temperature and at –78°C (strain rate =5·5.10^–5 sec^–1) are characterized by a dynamical yield point followed by a strong work-hardening. The plastic deformation starts by the movement ofa/2111 dislocations from several places of the specimen. Macroscopically, the dislocations move approximately along the planes with maximum resolved shear stress. Slip bands are formed by multiplication of the moving dislocations. They broaden and fill the whole specimen at a strain smaller than 0·1% or 0·2% for the deformation at room temperature and –78°C respectively. The corresponding dislocation densities are <4.10⁶ cm^–2 and 2.10⁷ cm^–2 respectively. At these strains a strong work-hardening begins. The mosaic structure causes an increase of the yield stress and of the difference between the upper and lower yield stress. Differences between iron and iron-3% Si alloy single crystals at the beginning of the plastic deformation have only a quantitative character and can be explained by the fact that the lattice friction stress in iron is approximately 15 times smaller than in iron-3% Si alloy.

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Vorgetragen auf der Diskussionstagung der Arbeitsgemeinschaft Metallphysik über Die Plastizität und Strahlenschädigung von Metallen und Legierungen, 10.–13. Oktober 1967; (diese Tagung wurde mit Unterstützung des Wirtschaftsministeriums Baden-Würtemberg durchgeführt).

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Herrn Dr. F. Kroupa möchten wir für die wertvollen Ratschläge zur Diskussion der experimentellen Ergebnisse und Frau Dipl. Phys. N. Zárubová für ihre Bemerkungen zum Manuskript danken. Frau I. Velartová sei für ihre Hilfe bei den Berg-Barrett-Aufnahmen gedankt.     

Das Reflexionsspektrum von Kadmiumoxyd-Einkristallen im Gebiet der Eigenabsorptionskante

The shift of the intrinsic absorption edge due to degeneration by high electron concentrations in the conduction band was investigated in CdO-single crystals by means of reflectivity measurements. The results are in good agreement with calculations afterFinkenrath. The absorption constant at the frequency of the lowest energy peak in the reflectivity has a value of aboutK≈0,4·10⁵ cm^?1.