ISSN:0232-1300    

DOI:10.1002/crat.2170290819

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170290820

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170290821

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170290822

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractExperimental results of the dependence of linear growth rates of ammonium oxalate monohydrate [(NH4)2C2O4· H2O; AO] single crystals on solution supersaturation are presented. The AO crystals were grown by constant‐temperature, constant‐supersaturation method at 30 and 40 °C in the supersaturation range of 1–9%. It was observed that the supersaturation dependence of growth rates follows the parabolic growth law. Analysis of the supersaturation dependence of linear growth rates of AO crystals showed (1) that growth models involving surface diffusion and direct incorporation of growth units give kinetic parameters similar to those reported for other compounds grown from solutions, and (2) that the the BCF model of cooperating screw dislocations is also applicable. An inverse relationship between the estimated values of the length,L, of the line containing the dislocations and growth rate,R, and a direct relationship betweenLand interplanar distance,dhkl, of the face {hkl} were found. Both these relationships are associated with the process of generation of screw dislocations in the growin

ISSN:0232-1300    

DOI:10.1002/crat.2170290802

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe shape and size of voids, and the grown region surrounding a large void were investigated in InxGa1–xSb crystals, which were pulled under the introduction of ultrasonic vibrations into the source melt by using a modified Czochralski apparatus. The presence of voids in crystals resulted from (1) atmosphere gas was confined beneath the growth interface of a seed crystal during the seeding procedure, and (2) many bubbles–generated by the cavitation effect due to ultrasonic vibrations–were caught in the growing crystal. Voids were circular, deformed trapezoid, and complex in shape, and were in a range of 20 μm to 3 mm in size. Even in case of a void with the diameter as large as 2 mm, the grown region surrounding it was in the single crystalline state. In this interesting region, the microscopic variation of In concentration and the abrupt change of growth rate were ob

ISSN:0232-1300    

DOI:10.1002/crat.2170290803

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractExperimental results for various states of buoyancy driven flow in vertical (Bi0.23Sb0.75)2Te3molten zones with covered surface are presented. Critical thermal wall Rayleigh numbersRa wc2for the onset of time‐dependent convection have been determined by means of temperature measurements. The stability diagram obtained for the existing buoyancy driven convection shows the increase ofRa wc2with increasing aspect ratio. This relation is also known from other crystal growth configurations and is due to the damping influence of container walls. At the beginning in the oscillatory region of convection extremely long periods of oscillation (maximum 850 s) were observed, which are caused by another mechanism than periods (25 … 37 s) registered at increasing melt heights. Furthermore, Bi0.5Sb1.5Te3crystals were grown by using the vertical zone melting technique. The microscopic striations observed in the grown crystals correlate exactly with the temperature signals caused by time dependent convection. However, the fluctuations of the tellurium distribution in axial direction measured by scanning the Seebeck coefficient are presumably generated by unsteady solutal convection during

ISSN:0232-1300    

DOI:10.1002/crat.2170290804

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractBy the analysis of X‐ray reflectivity angle dependence the existence of a characteristic nucleus heighthin the island stage of nickel growth have been found. As the condensation time τ rises, the value ofhincreases according to a linear law, and the portion of substrate surface occupied by nuclei is described by a curve with saturation. The formation latent period of the fraction with preferential sizehis extremely small, that, in principle, allows to produce smooth surfaces, even if the effective thickness is only about several atomic layers. The kinetic characteristics are identical both at growing on monocrystalline silicon and amorphous SiOxsubstrat

ISSN:0232-1300    

DOI:10.1002/crat.2170290805

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractExperiments intended to improve the quality of seed plates for hydrothermal synthesis of quartz crystals have been performed. The plates were subjected to electro‐sweeping of alkali cations. More perfect crystals were grown on such seed

ISSN:0232-1300    

DOI:10.1002/crat.2170290806

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe existing models describing growth rate dispersion don't consider a healing process of crystal damages or surface defects. In this paper a model is presented which takes into account such a healing process. With regard to the new model formulas, characterizing the crystal size distribution, are derived from the population balance and discussed. The considerations are extended to continuous crystallizers.

ISSN:0232-1300    

DOI:10.1002/crat.2170290807

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY