摘要:

AbstractThe growth behaviour of ammonium oxalate monohydrate crystals on seeds from aqueous solutions under terrestrial and enhanced gravity conditions has been investigated. It was found that all types of faces on the crystals revealed growth layers on them. The faces of the crystals obtained under both terrestrial and enhanced gravity conditions on seeds hung on nylon threads show cracks, trapped inclusions and macrospirals, while the faces of the crystals grown on seeds in fixed holders under enhanced gravity conditions are devoid of cracks, inclusions and macrospirals.

ISSN:0232-1300    

DOI:10.1002/crat.2170270802

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe growth kinetics of the pyramidal face of zinc single crystals is studied in the presence of argon. The curves size vs. time provide evidence that smaller crystals grow in a kinetic regime and after reaching a certain critical size their growth continues in a diffusion regime. The growth kinetics of faces {101} and {0001} are compared. It is established that the growth of both faces simultaneously changes from a kinetic to a diffusion growth mode. During the transition between the two regimes, however, loss of the morphological stability only of the smooth {0001} face is observed, while the {101} face with macro steps formed on the surface acquires a skeletal shape after prolonged growth. It is shown that the appearance of morphological instability depends on the surface structure of the crystal faces.

ISSN:0232-1300    

DOI:10.1002/crat.2170270803

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractMgZrO3was synthesized by tribochemical and thermal treating of a mixture of MgO and ZrO2corresponding to its stoichiometry. The gained compound is identified by chemical and X‐ray analysi

ISSN:0232-1300    

DOI:10.1002/crat.2170270804

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170270805

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170270806

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractLarge synthetic crystals of alkaline earth metal fluorides, especially fluorite crystals, contain sometimes unknown small inclusions of hexagonal form. Samples of these crystals were investigated by microscope, X‐ray, and microprobe analysis to identify the included small crystals. Optical behaviour of these inclusions, morphology, chemical composition, and the reaction with water allow their interpretation as high‐temperature modifications of the anhydrous water soluble alkaline earth metal sulfates, partly transformed to the corresponding sulfi

ISSN:0232-1300    

DOI:10.1002/crat.2170270807

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170270808

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractRoom‐ and high‐temperature micro‐indentation experiments have been performed to answer the question if, concerning a material with very low stacking‐fault energy like CdTe, deformation induced twinning occurs in these substances during or shortly after growth.Micro‐twins appear in consequence of room‐temperature deformation only, whereas microindentation at 565°C does not produce any twins, but leads to widely expanded dislocation glide‐figures, due to dislocation climbing and/or

ISSN:0232-1300    

DOI:10.1002/crat.2170270809

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170270810

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIt is known that it is possible to grow a semi‐insulating or, at least, a high resistivity GaAs epitaxial layer without doping on an SI GaAs substrate by VPE. The SI substrate is suspected as the originator of the high resistivity intermediate layer and diffusion and/or out‐diffusion are accepted as mechanisms explaining this effect. In this work carrier concentration depth profiles were studied in various GaAs multi‐layered epitaxial structures grown on SI GaAs substrates before and after various heat treatment procedures in order to study the diffusion and outdiffusion processes. It is concluded that the role of the diffusion is negligible and the out‐diffusion process is insignificant, and the main, i.e. the determining effect in the compensation process is the growth mechanism of the layer. The impurities set free from the substrate by chemical etching processes rebuilt into the growing layer. In addition formation of EL2 centres may be initiated by As rich gas phase composition following the in‐sit

ISSN:0232-1300    

DOI:10.1002/crat.2170270811

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY