Die Abhängigkeit der Röntgenemissionsspektren vom chemischen Bindungszustand und der kristallographischen Orientierung der Proben und die Bedeutung dieser Effekte für mikroanalytische Untersuchungen

It is shown that also more subtle X-ray spectroscopic effects such as the dependence of the spectra on chemical bond and crystallographic orientation (of monocrystalline samples) can be measured by means of modern electron microprobe analysers because of their high resolving power. When neglected these effects can falsify microanalytic measuring data, but they also can widely extend their information content which is demonstrated at hand of examples. Some possibilities of applications of the electron microprobe analysers for fundamental investigations in the field of X-ray spectroscopy (e. g. energy band structure of solids) are demonstrated and specific advantages of their use are referred to.     

Die Bedeutung mechano-elektrischer Erscheinungen für die Bestimmung der Oberflächenenergie von Kristallen

Using the method of crystal cleaving a calculation of the surface free energy of mica is given. For this an effective elastic stiffness constant is introduced, this taking into consideration the electrostatic charging of the crystal surface. For measuring the charges arising from the cleaving of the crystal a special experimental equipment is used. Microgeometry and mechano-exoelectronic flow are determined. With sufficient high vacuum the latter becomes the main process of stabilizing instable electric crystal surfaces. The electrostatic charging only little affects the values of measured surface energies. The deformation, however, of layers near the surface gives a larger effect. Considering this deformation a surface free energy of 380 erg · cm⁻¹ for mica is given.     

Berechnung der Verteilungsfunktion für einen periodisch veränderlichen Verteilungskoeffizienten beim Kristallwachstum nach dem Kyropoulos-Verfahren

Periodically appearing segregation processes during Kyropoulos growth of doped single crystals were treated quantitatively using a sinusoidally varying distribution coefficient. The shape of the average dopant concentration and of the amplitude of the oscillation of the dopant could be calculated as a function of the crystallized part of the melt. Characteristic parameters influencing this shape are discussed. The calculation is applied to the growth of Ca doped KCl crystals.     

Anwendung der Umweganregung für die Bestimmung der Güte von Kristalloberflächen

The intensity relation of two “Umweganregungs” reflections (double reflections) in case of an anisotropic distribution of mosaic blocks is calculated. The measurement of the intensity relations of double reflections pairs allows the determination of the average disorientation of the mosaic blocks.     

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.     

Ableitung der Verteilung von Kornlängen für drei einfache eindimensionale Erstarrungsprozesse

At first in this theoretical article a melt in a capillary tube is considered, when appearing a number of nuclei by undercooling. The distribution function of the distances between neighbouring nuclei is deduced by use of the theory of stochastic processes. The average of these distances is the parameter in the distribution function. Under this supposition for the nuclei-distances the distribution functions of the length of crystals, forming by three different ways of crystallization in the capillary tube, is deduced.     

Zur Errechnung der Intensitäten von Auger-Übergängen für die quantitative Analyse von Festkörperoberflächen mit der Augerelektronenspektroskopie (AES)

According to an empirical equation for the Auger electron intensity arising from primary electron bombardment of solid surfaces, the parameters such as ionization cross section, relative Auger transition probability, backscattering factor and mean escape depth were evaluated for the L₃M₄₅M₄₅ Auger transition of elements with atomic number Z = 22 to 33. A comparison of the calculated relative intensities with experimental values from Palmberg et al. indicates a good agreement of both curves representing the intensity in dependence of atomic number. The mean relative deviation of calculated intensities from measured ones amounts to 20%. This is nearly the same value, as it has been estimated so far for the accuracy of quantitative AES without standard. Examining the influence of individual intensity parameters we were able to show that above all the ionization cross section and in the present case also the relative Auger transition probability determine the value of intensity.     

Zur Bestimmung von Aktivierungsparametern für die Stoffübergangs- und Stofftransportprozesse an AgCl- und AgBr-Kristallen mittels radioaktiver Nuklide

A report is given on radiochemical measurements carried out by means of the nuclides ^110mAg⁺, ^82mBr⁻, and ³⁶Cl⁻ in order to determine the activation parameters of the mass transfer processes in AgCl and AgBr in the course of the Ostwald Ripening, examining in particular the influence of the thermal pretreatment and the ageing of the AgCl and AgBr upon the activation parameters. Comparative investigations of the systems AgCl_(s)-^110mAg⁺_(aq) and ^110mAgCl_(s)-Ag⁺_(aq) showed that the mass transfer processes on the crystal (incorporation of the ions into the crystal lattice and detachment of the ions from the lattice points, respectively) as well as the mass transport processes in the crystal lattice (diffusion of the Ag⁺ ions through interstitial sites) can be rate determining, the dehydration of the Ag₊ ions, however, should not be dominant, as has also been proved by measurements in mixed solvents.     

Näherungsverfahren für die Integraldarstellung von Beugungsintensitäten gestörter Kristalle

For the calculation of the electron microscopic diffraction contrast without column approximation a solution is given by a perturbation calculation. Applying this to the two-beam case one gets integral representations for the amplitudes of the diffracted waves.     

Über die Züchtung von ZnS-, ZnSe- und ZnTe-Einkristallen unter Anwendung der chemischen Transportreaktion

In connection with investigations on the synthesis of ZnS, ZnSe and ZnTe single crystals by chemical transport using iodine as transport agent in sealed tubes the mechanism of mass-transport and the relationship between material-transport and growth process were studied. In this way the optimum conditions for growing single crystals were found. The dependence of the transport rate on the undercooling ΔT, on the diameter of the ampoule and on the pressure in the system is described. Relative large crystals in good quality could be propared by influencing the nucleation and the growth process by help of well defined transport rates. In all cases crystals with sphalerite structure only were obtained. The habit with the most common faces (110), (111) and (211) was found to be predominant. The dominant habit is responsive to variations in the experimental parameters. The crystal perfection have been determined by etch patterns and by X-ray topography.     

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.     

Die Phasenübergänge und die Störstellenphotoleitung von Sb2S3

The influence of the Sb₂S₃ single crystals growing conditions on the mikrowave dielectric permittivity and the photoconductivity has been investigated. An improper photoconductivity arises on the ferroelectric plane (001) in the crystals with a high dielectric permittivity.