摘要:

AbstractThe effect of the scope of interaction between the atoms in two‐dimensional and threedimensional clusters containing 6, 7, 9, 10, 15 and 16 lithium atoms, upon the binding energy (BE) of the clusters has been investigated.BEof the clusters was calcuated by the HÜCKELMolecular Orbital (HMO) method.It has been established that for clusters with the same number of atomsBEhas its maximum value when the interaction of each atom of the cluster with the atoms of its first and second coordination spheres in the lithium lattice are taken into account. After the maximumBEdecreases and tends to a constant value which is attained when the interaction of each atom of the cluster with the atoms of its six coordination spheres is taken into account.The reasons for the above result should be looked for in the limits of applicability of the calculation procedure based on the HMO method to the study of properties of various models of clusters containing a small number of metal (e.g. lithium) ato

ISSN:0232-1300    

DOI:10.1002/crat.2170170402

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractIt has been proved experimentally that at the codeposition of silicoan and boron at low concentrations of boron, being comparable with the residual water vapour of the gases, gaseous phase reactions ake place, decreasing the incorporation of boron in the deposited silicon. Probably silioxy‐boron‐halides are formed in these reacti

ISSN:0232-1300    

DOI:10.1002/crat.2170170403

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe device for growth process and quality of the growing calomel (Hg2Cl2) single crystals studying is described. The function of the apparatus is based on the analysis of the information modulated on the poychromic light beam passed through the growing crystal. By means of this method the device determinates the temperature and the quality of the growing crystal. In the second part of this paper the special TV equipment is described. By means of that an information about the temperature and quality distribution in the whole growing crystal is obtained.

ISSN:0232-1300    

DOI:10.1002/crat.2170170404

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe submicroscopic structure of synthetic Hg2Cl2monocrystals was investigated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), indirect imaging of surfaces (Pt/C replica technique) as well as by application of supplementary methods. As already reported by NEUMANNet al., TEM‐images show a periodic stripelike contrast whose period varies from 0.1 m̈m to 0.2 m̈m. It proved that the stripelike contrast arises from a periodic chemical inhomogeneity of the synthetic crystals. The chemical inhomogeneity probably consists in periodic deviations from the stoichiometric composition of Hg2Cl2. By reason of the orientation on {110}‐, (001)‐, and {114} faces a reconstruction of arrangement of the structures in the crystals is carried out. According to that, the stripes have to be interpreted as intersection lines of 2‐dimensional formations with the correspond

ISSN:0232-1300    

DOI:10.1002/crat.2170170405

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe optical unpolarized absorption spectra of Hg2Cl2and Hg2Br2single crystals were measured in the spectral range 230–400 nm. A sharp exciton peak and other absorption bands of both halides were observed near the fundamental absorption edge. The absorption peaks due to the splitting of the halogen doublet were also observed. Positions of the exciton peaks are characteristic for the Frenkel (localized) type of excitons. Possible interpretations of the other observed bands are discusse

ISSN:0232-1300    

DOI:10.1002/crat.2170170406

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe present work deals with the applicability of the mercurous halide crystals to the production of polarizers of light. The wide transmission region of these crystals mainly in the infrared region allows to use them for wavelenghts up to about 20 m̈m for mercurous chloride and 30 m̈m for mecrurous bromide. Especially high double refraction allows a construction of classical polarizer types having very advantageous parameters, i.e. small thickness of the element and large angle of splitting of the ordinary and extraordinary ray. Besides, high double refraction allows an original design of single‐piece (monolithic) polarizers which are characterized by relatively simple treatment, high quality and low los

ISSN:0232-1300    

DOI:10.1002/crat.2170170407

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractWithin the framework of the systematic study of differences in physical properties of the calomel (Hg2Cl2) single crystals before and after surface treatment, the differences in the microhardness, the residual stress in the surface layer, and the chemical etching rate were investigated on the (110) and (001) crystal faces. It has turned out that Beilby layer (B‐layer) formed during surface treatment is softer, and, on the cleavage surface is harder than the underlying bulk material. The thickness of the B‐layer in these samples ranged between 5 anf 7 m̈m. Further it has been found that a tensile residual stress s̀ = 14 Nm‐2prevails in the surface layer of a polished (110) face to a depth of 70 m̈m and, after grinding, to a depth from 90 to 200 m̈m. On the other hand, a compressive stress has been found in the natural cleavage plane. Experiments on etching the Hg2Cl2crystals with HCl + HNO3etching solution have shown that the rate of chemical etching is 2 to 4 times larger on the (110) face than on the (001) face. Differences are very strongly dependent on the experimental conditions and on the real structure of a give

ISSN:0232-1300    

DOI:10.1002/crat.2170170408

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe method of plasma (ionic) etching provides information on both the degree of damage and the real structure of a treated surface of a cleavage crystallographic plane (110). The altered surface structure of this plane, which is due to cutting, grinding and polishing, is a cause of a rapid loss of calomel at the beginning of the etching process. The minimum loss rate is directly proportional to the thickness of the damaged surface. The ensuring rapid loss of calomel is due to an increased ruggedness of the surface. The ionic etching of calomel on the crystallographic plane (110) proceeds in six phases which are documented in photographs. The method of ionic etching is promissing for a high‐quality treatment of surfaces of calomel acousto‐optical functional elements designed for connections with ultrasound transduc

ISSN:0232-1300    

DOI:10.1002/crat.2170170409

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractPlagioclase crystals Ab20An00and nearly pure anorthite were grown on the surface of artificial melts by hydrothermal treatment at 2 kb. The average crystal size was 0.002 to 0.008 mm. In the temperature range of 400° to 600°C a pseudohexagonal habit was observed for anorthite while a lath‐like habit due to the prevalence of {010} was found for the Ab20An80composition. Dominating faces are {010} {130} {110} {100} {110} {130} in the zone [001] and {021} {111} {111} {021} {111} {111} together with {0

ISSN:0232-1300    

DOI:10.1002/crat.2170170410

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractSingle crystals of cadmium iodide have been grown from melt using Bridgman‐Stockbarger system and their polytypism studied by X‐ray diffraction. The initially grown crystals were found to stick to the walls of the ampoule and had black specks of impurity suspended in them. A systematic study has been carried out to determine the effect of degree of vacuum, material of the ampoule and quality of raw material on crystal growth. It has been concluded and later verified using zone‐refined material that the observed sticking essentially stems from the presence of impurities in the raw material. From X‐ray diffraction it is found that all crystals belong to the most common polytype 4

ISSN:0232-1300    

DOI:10.1002/crat.2170170411

出版商:WILEY‐VCH Verlag    

年代:1982

数据来源: WILEY