ISSN:0232-1300    

DOI:10.1002/crat.2170201002

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA theory connected with spontaneous fluctuations of the limited spectrum solid state particle concentrations in the case of binary metallic macrosystems crystallizing from the binary melts is developed. Normal kinetics was found to be realized in the case of very dilute binary metallic solid solutions within the small ‘supercoolings’ region. A comparison between the theoretical and experimental data on the crystallization kinetics of very dilute binary metallic solid state solutions within the small ‘supercoolings’ region has been made. For some types of binary metallic macrosystems the quantitative restrictions of the supercooling regions within which a fluctuation mechanism and normal kinetics are assumed to act have been established. The restrictions are conditioned by some parameters of the binary macroscopic melt and two‐phase transitional zone c

ISSN:0232-1300    

DOI:10.1002/crat.2170201003

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractNielsen's equation has been applied for cooling crystallization of KCl from watery solutions. In the calculations activities are used instead of concentrations, the temperature and concentration dependence of both the activity and diffusion coefficients are considered. It is found thatA) the interfacial tension between the crystal and its saturated solution is<2.5 erg/cm2, which is less by two orders of magnitude than that of between crystal and vacuum;B) homogeneous nucleation can take place even at very small supersaturations (lnS<<0.01), which is unusual in precipitation.

ISSN:0232-1300    

DOI:10.1002/crat.2170201004

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe influence of the natural convection on the heat and mass transfer process during growth of GaP crystals from the solution is considered. The two‐dimensional quasi‐stationary thermodiffusive hydrodynamic problem for the GaP growth system by travelling solvent method (TSM), as a model, has been solved. Computation is given for the temperature and concentration field distribution in the solution. The picture of vortex configuration for different lengths of the liquid zone, the shape of the growing and dissolving interfaces and also the boundary layers thickness are obtained. The experimental dependence of the growth rate on the convection intensity observed mostly confirmed the calculation resu

ISSN:0232-1300    

DOI:10.1002/crat.2170201005

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractCalcium aluminium hydroxides were coprecipitated from different mixed metal cation solutions — at totalCM= 0.1 M and Ca/Al2ratios from 1 to 4 — with sodium hydroxide solution at ambient temperature. The coprecipitations were monitored by potentiometric (pH) titration and the final coprecipitate compositions were examined by chemical analysis, infra‐red spectrophotometry and thermal analysis Generally, microcrystalline aluminium hydroxide was first precipitated atpH about 4; this then redissolved on further addition of sodium hydroxide to form hydroxoaluminate anion and polyanion and calcium aluminium hydroxide coprecipitates were formed continuously atpHs from about 9 to above 12. Their compositions were similar to the calcium hydroxoaluminate hydrates formed by direct precipitation from highpH sodium hydroxoaluminate solutions.At Ca/Al2ratio = 1, the main phase was probably Ca2(H2O)h[Al2(OH)4]2with some Al(OH)3;At Ca/Al2ratio = 2, the main phase was probably Ca2(H2O)h[Al2(OH)10] dehydrating to Ca2[Al2O(OH)8];At Ca/Al2ratios = 3–4, the main phase was Ca2(H2O)h[Al2(OH)10] with increasing amounts of Ca4(H2O)h(OH)4[Al2(OH)10] and 5–10 percent adsorbed or post‐precipita

ISSN:0232-1300    

DOI:10.1002/crat.2170201006

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractStudies on the crystallization of mixtures of palmitic acid: n‐octacosane at elevated temperatures is presented. The crystallization temperature is seen to have a pronounced effect on the morphology of the banded structures. The fibre twist which is responsible for the band formation, is interpreted as due to a thermal stress. Crystallization of some other compounds in the presence of n‐octacosane is described and the results are discus

ISSN:0232-1300    

DOI:10.1002/crat.2170201007

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDie Kristall‐ und Molekularstruktur der Titelverbindung wurde mit Hilfe der Röntgenkristallstrukturanalyse bestimmt. Sie kristallisiert in der monoklinen Raumgruppe P 21/c mit den Gitterkonstantena= 8,760 Å,b= 26,863 Å,c= 9,678 Å und β = 106,03°. Die Struktur wurde mit der Schweratomtechnik gelöst und mit der Methode der kleinsten Quadrate bis zumR‐Wert von 0,075

ISSN:0232-1300    

DOI:10.1002/crat.2170201008

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDie Titelverbindung kristallisiert in der monoklinen Raumgruppe P 21mit 2 Formeleinheiten C8H12N4O2in der Elementarzelle. Die Gitterkonstanten sinda= 8,529,b= 11,735,c= 4,925 Å und β = 94,61°. Die Kristallstruktur wurde mit direkten Methoden bestimmt und mit der Methode der kleinsten Quadrate bis zu einemR‐Wert von 0,033 verfei

ISSN:0232-1300    

DOI:10.1002/crat.2170201009

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractStudying a number of {101} faces of KDP and DKDP single crystals in the as‐grown state we found in most cases one, rarely few, clearly stepped growth hillocks covering the whole face. The geometry of these growth hillocks was determined from photomicrographs; the step heights were measured with a profilometer. To prove our results we carried out X‐ray topographic investigations and in‐situ observations on KDP crystals. In addition we studied the as‐grown faces of ADP and LiJO3single c

ISSN:0232-1300    

DOI:10.1002/crat.2170201010

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe influence of both the concentration and dispersion state of the dopant upon the behaviour of the high‐temperature depolarization‐band was thoroughly studied for NaCl und KCl crystals doped with Eu++, Pb++, and Ni++ions.It has been evidenced that the behaviour of this band can be better explained in frames of the Maxwell(Wagner)Sillars‐model adapted for the dislocation lines surrounded by the Cottrell‐like atmospheres than by the Müller's‐model related to the excess charge conductivi

ISSN:0232-1300    

DOI:10.1002/crat.2170201011

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY