Quantenmechanische Gesetzmäßigkeiten bei Kristallisationsprozessen an Phasengrenzflächen von Ionenkristallen (III)

The activation energies for the phase boundary processes on AgCl and AgBr precipitates were measured by the method of labelled atoms and compared with the values obtained by quantum mechanical calculations. A good agreement of the measured and the calculated values was found. – Quantum mechanical laws in mass transfer processes at the phase boundaries of AgCl and AgBr precipitates are discussed. A direct proportionality exists between the activation energy for the mass transfer in crystallization processes and the interfacial energy, respectively, and the frequency of the longitudinal optic phonones, the proportionality constant being the Planck's constant.     

Zur Bestimmung des effektiven Verteilungskoeffizienten von Te bei der Züchtung von GaP-Einkristallen aus nichtstöchiometrischen schmelzen

An equation for determining the effective distribution coefficient, k_eff, under the conditions of growing single crystals from non-stoichiometric melts is proposed. This equation is used for the calculation of k_eff at Te concentrations in the melt from 3.5 × 10⁻³ up to 9.1 × 10⁻² at.%. From numerous measurements a k_eff value of 0.070 with the 1 σ boundaries at 0.116 and 0.043 is found. The relatively wide spread is accounted for by the heterogeneous distribution of doping material which is due to the technique applied and to the polar properties of the GaP lattice.     

Zur quantentheoretischen Berechnung von Aktivierungsenergien für den Stoffübergang an Phasengrenzflächen von Ionenkristallen bei Kristallisationsprozessen (I). Zur Bestimmung von Aktivierungsenergien für den Stoffübergang an Phasengrenzflächen leichtlöslicher Salze mittels radioaktiver Nuklide

A report is given on the determination of the activation energies for the mass transfer processes at phase boundaries of ionic crystals by means of the method of labelled atoms. In order to obtain reproducible activation energies from the temperature dependence of the mass transfer numbers, the influence factors stirring speed, supersaturation, pretreatment and surface condition of the crystals, grain size distribution, and suspension density must be kept constant. For different ranges of temperature, different activation energies were obtained, which are explained by the desolvation of the ions and the incorporation of the ions into the crystal lattice.     

Über die Richtigkeit und Genauigkeit bei der Messung von Netzebenenabständen

The paper emphasizes the principal difference between the terms deviation and error. The relative deviation as a measure of accuracy can be expressed by the total differential, while the relative error as a measure of precision can be calculated by means of the law of error propagation. From this view point the up-to-date treatments of the Braggs differentiated equation in the direct and reciprocal space is discussed and new approached.     

Der Einfluß der Rauhigkeit der Probenoberfläche auf die Ergebnisse ellipsometrischer Messungen bei GaAs

The results of ellipsometrical measurements on GaAs show some discrepancies. This fact is discussed using a simple model of the rough GaAs surface. It is demonstrated in what way a rough surface influences the ellipsometrical measurements of the film thickness and the refractive index.     

LEED-Auger-Untersuchungen an der (100)-Fläche austenitischer Chrom-Nickel-Stähle

The results of LEED-Auger studies on a (100) surface of stainless steel show that sulphur segregates from the bulk of single crystals to the surface during heating under ultra-high vacuum conditions and induces a c(2 × 2) structure. After heating the samples to 1100°C with subsequent rapid cooling (maximum temperature change of 200 K/s within the temper range) the sulphur-covered surface can be removed. Up to 700°C the cleaned surface is sufficiently constant for additional studies.     

Berechnung der Übersättigung bei der Kristallisation von InAs aus der Gasphase

It is proved that under experimental conditions for the growing of InAs crystals from the vapour phase the partial supersaturation of indium monoiodide corresponding to the difference of partial pressure of InJ_(g) in the source and in the crystallisation zones, can serve as a quantitative process parameter granting predictions on process development and results in a wide range of ruling conditions. Experiments confirmed the conclusions postulated on the base of quantitative analysis of the transport process. The analysis enables to controll the process parameters of crystal growth by chemical transport.     

Oberflächenstörungen und Hohlwachstum bei der Züchtung von β-Kupferphthalocyanin-Einkristallen aus der Gasphase

Hollow crystals are obtained frequently during the growth of copper phthalocyanine single crystals from the vapour phase. This appearance makes some physical investigations impossible. To overcome these difficulties some ways are discussed. The reasons for hollow growth are instabilities in the growth caused by diffusion controlled inhomogeneities in supersaturation on the growth front. This was found by observations of surface defects and by defined growth experiments. By introduction of special methods of growth and use of defined parameters one obtains bulk crystals of larger extent up to 1 mm in cross direction. References are given in the field of hollow crystal growth in the vapour phase of other substances.     

Zur quantentheoretischen Berechnung von Aktivierungsenergien für den Stoffübergang an Phasengrenzflächen von Ionenkristallen (IV). Zur radiochemischen Bestimmung und quantentheoretischen Berechnung von Aktivierungsenergien für den Stoffübergang an den Kristallflächen des NaCl

It is shown that a direct proportionality exists between the activation energy for the mass transfer at the respective crystal faces of ionic crystals and the frequency of the phonones (longitudinal-optical), Planck's constant being found once more as a proportionality constant. Thus it could be demonstrated that the different activation energies measured at different time intervals for the mass transfer processes at phase boundaries of ionic crystals can be attributed to the specific growth of the crystal faces. Thus, NaCl crystal fractions which were mechanically stressed (pulverized and sifted) and consequently contained a great amount of {111}- and {110}-faces, respectively, experimentally yielded an activation energy wich agrees with the values determined by quantum theory when the frequency of propagation of the phonons is inserted into a derived equation. This relation was also confirmed by NaCl crystal fractions predominantly containing cubic faces. This was indicates that in mass transfer processes on phase boundaries of ionic crystals quantum mechanical laws are of importance.     

Spezielle Strukturbaufehler in gasdotierten Silizium-einkristallen und deren mögliche Wirkung bei der Herstellung von pn-Übergängen

Investigation and identification of special imperfections of silicon single crystals prepared by gas doping and zone floating are reported. Investigation methods used are etch technique, X-ray topography and electron beam micro-analysis. It was stated that the investigated imperfections show oxygen clusters. A possible growth process of such imperfections is discussed. In conclusion, first results of investigations on the effects of such imperfections during the formation of p–n junctions are given.     

Zur Bestimmung der Mikrohärte von Baryt-Einkristallen bei hohem hydrostatischen Druck

An apparatus to generate high pressure up to 12000 kp · cm⁻² and a microhardness device to be put in it are described. The pyramid identations originate from the moving force of the falling indenter. To compare microhardnesses at normal and high pressure the viscosities of the pressure fluids are assimilated. For that purpose the microhardness device served as viscosimeter. With extrapolated falling height zero of the idennter and a load of 36 g the (001)-surface of Baryt single crystals have a microhardness of about 210 kp · mm⁻² at a hydrostatic pressure of 10000 kp · cm⁻². The corresponding microhardness at normal pressure is 90 kp · mm⁻²     

Bestimmung von Diffusionskoeffizienten aus der Röntgen-Kleinwinkelstreuung und Lichtstreuung von Gläsern

It is shown how to conclude from small angle X-ray scattering and light scattering of phase separated glasses what kind of phase separation process is occurring in the glass. In the cases of diffusion controlled particle growth and of spinodal decomposition, methods were presented permitting to find out from diffraction experiments the diffusion coefficients underlying these decomposition processes. The methods were demonstrated with three different glasses.     

Die Struktur der Oberfläche fester Körper

Assuming the row of particles in a lattice to extend from n = – ∞ to n = 0, with all particles n = 1, 2, 3, …︁ missing, the force is discussed to be added in order to keep the periodicity of structure near the end of the row. Forces that would make up exactly for the forces that the missing particles would produce on the end of the row must be provided for. If the total force is differently distributed between the particles at the end of the row, different things may happen, in that a perturbation appears near the end of the lattice or even along the whole lattice. This example corresponds to the problem of surface structure and surface tension for solids. The perturbation of the lattice inside a surface layer results in additional forces, the resultant of which is known as surface tension.     

Beziehungen zwischen Beilbyschicht und Oberfläche fester Körper

The investigation of the influence of the Beilbyschicht upon thin plates begins with the statement of the distortion of the plate by calorification during its generation. The enhancement of the temperature of the material curves the middle surface of the thin plate into a thin shell. The curvature exist after plates being cooled.