摘要:

AbstractA relationship exists between the size of the particle and nucleation temperature. There exists an optimum particle size below which nucleation is inhibited. The behaviour of lead iodide thin films as a substrate for ice nucleation is reported in this study. It is found that the supercooling increases with increase in the thickness of the film. But the change in nucleation temperature above 1250 Å is negligible

ISSN:0232-1300    

DOI:10.1002/crat.2170200202

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170200203

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe conditions (concentration andpH) for preparation of single crystals of struvite at 25 °C from ammoniacal solutions equimolar with respect to magnesium and phosphate ions are given. The limits are found above which crystal aggregates (twins or dendrites) precipitate as dominant morphology. The mechanisms of nucleation are discussed and the interfacial tension between crystals and solution is evaluated

ISSN:0232-1300    

DOI:10.1002/crat.2170200204

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractAlSi type eutectics (AlSi, AgSi, AgGe, ZnGe) form 〈100〉 — textured eutectic dendrites of the semiconductor phase when a certain growth rateRand liquid temperature gradientGare held. The spacings of these eutectic dendrites λ follow the relationship: λ = (rλ≈︁ 0.2;g≈︁ 0.5). The exponents of this relationship can be explained by the model of phase lead determined growth. This model is based on the consideration of the analogy to dendrite growth. The AlSi type eutectics have geometrically similar morphologies for determinedGx/R‐relations (x= 1.25 in the case of AgGe) and the relation λ2R= const. is valid. In this paper the AgGe eutecti

ISSN:0232-1300    

DOI:10.1002/crat.2170200205

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170200206

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractUsing modified preparation conditions for silicate and aluminate solutions some differences in the result of large A‐ and X‐type zeolites crystallization utilizing Charnell's procedure have been obtained. A‐type zeolite crystals show clearly {110} faces. X‐type zeolite occurs in mixed phase together with A‐type zeolite as separate as well as overgrown crystals. These observations can be explained by structure defects in A‐type crystals and by presence of polysilicate or/and too high aluminium content

ISSN:0232-1300    

DOI:10.1002/crat.2170200207

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe process of the Stepanov growth of sapphire tubes is studied at the growth rates up to 20 mm · min−1in a Mo crucible with graphite succeptor. It is established that the main factor preventing the production of high‐quality samples is contamination of the melt due to the gas transport reactions the growth chamber atmosphere and formation of oversaturated carbon solid solution in the Al2O3matrix. The decomposition of this solid solution gives rise to the second‐phase‐particle precipitations. The production of highquality sapphire tubes at the growth rates up to 20 mm · min−1is possible with a careful elimination of water vapours and oxygen from the growth chamber

ISSN:0232-1300    

DOI:10.1002/crat.2170200208

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe process of single crystal pulling is considered with simultaneous starting material make‐up into the melt and heater temperature control in response to a signal generated by the electronic contact melt level sensor, viz.: (i) conditions ensuring the radial broadening steadiness; (ii) effect of melt level displacement, melt temperature changes, changes of solid/liquid interface shape, melt evaporation on the growing crystal diameter; (iii) conditions of crystal purification from impurities and uniform distribution of dopan

ISSN:0232-1300    

DOI:10.1002/crat.2170200209

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThree different methods have been proposed for quantitative description of agglomeration: visual determination of the percentage of agglomeration, numerical correction of crystal size distribution leading to the degree of agglomeration and the method of decomposition of the two‐peak crystal size distribution. The effect of neglecting the agglomeration on kinetic data of crystallization calculated from crystal size distribution may be very significan

ISSN:0232-1300    

DOI:10.1002/crat.2170200210

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractIn the present work connection between magnetic properties and texture of two samples of the tetragonal MnAl phase are investigated. For texture studies classical angle dispersive neutron diffraction and neutron time‐of‐flight method have been applied. the process of specimen preparation is shortly described. The mathematical treatment of experimental data for complete texture analysis has been outlined. The texture of investigated samples is weak. Some main components in inverse pole figures are inclined with respect to the direction of easy magnetization. In this way the non‐optimal magnetic properties of the investigated material can be expl

ISSN:0232-1300    

DOI:10.1002/crat.2170200211

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY