ISSN:0232-1300    

DOI:10.1002/crat.2170210427

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170210428

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractAs previous studies have shown (Spitsyn et al.; Henderson, Wertz; Steinike et al. 1981, 1984; Hennig et al.), mechanical activation of MgO in air results in the generation of anion and cation vacancies in the lattice, thus causing heterogeneous lattice distortions. These anion and cation vacancies are identified as F+‐ and V−‐centres, respectively, by EPR spectroscopy. F+‐centres are anion vacancies filled with electrons, V−‐centres are cation vacancies filled with holes. The electrons and defect electrons filling the vacancies are generated essentially during γ‐irradiation. Since the effect of the ambient atmosphere on the generation of electronic and structural defects upon mechanical activation is known (Bystrikov et al.), the studies of mechanical MgO activation in air were extended to the generation of above defects in an argon atmosphere. The results are compared with those o

ISSN:0232-1300    

DOI:10.1002/crat.2170210429

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170210430

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractFrom data of both X‐ray phase analysis and differential thermal analysis, as well from measurements of the crystal lattice parameters, electric conductivity and diffusion coefficients of cations in ceramics and single crystals the width of the homogeneity region of the lead molybdate phase which lies in the composition range of 49.85–50.50 mole% MoO3, has been determined. It was also established that the compound was a daltonide phase. The results obtained explain the Pb/Mo ratio changes along the crys

ISSN:0232-1300    

DOI:10.1002/crat.2170210402

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractDendritic growth of Ammonium tartrate single crystals in silica gel at 30 °C is reported. Main stem parallel to the ‘C’ axis is observed. Dendritic growth in initial and final stages with its surface structures are illustrated and described. Growth features are correlated to the growing conditions and reacting compon

ISSN:0232-1300    

DOI:10.1002/crat.2170210403

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractPrecipitates of the metastable R′‐phase grown in an Al‐(6.8 at.%)Zn alloy are investigated by means of a technique of high resolution electron microscopy, namely by two‐beam lattice fringe imaging with tilted illumination. It is demonstrated by this direct method that the R′‐precipitates are in fact semicoherent. The transition of fully coherent Guinier‐Preston zones into semicoherent precipitates of the R′‐phase takes place by formation of additional (III)rhand { III }rh

ISSN:0232-1300    

DOI:10.1002/crat.2170210404

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe morphology and structure of amorphous precipitates grown by thermal annealing in the temperature range from 1100 °C to 1200 °C are investigated by means of highvoltage electron microscopy. It is shown that there exist some characteristic morphological types which are equivalent to the equilibrium forms of the cubic diamond structure itself or which can be derived from these. For the growth process an oxygen diffusion‐controlled mechanism is deduced. Structural aspects are discussed on the basis of this mechan

ISSN:0232-1300    

DOI:10.1002/crat.2170210405

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170210406

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractMicrotopographical studies on habit faces of gel grown crystals (of different habits) of iodates of Ba, Sr, and Ca are illustrated and described. Etch patterns on these faces are illustrated and correlated to the observed growth patterns on the respective faces. Growth mechanism of the crystals is explained in light of the observed surface structures and etch pits suitably produced.

ISSN:0232-1300    

DOI:10.1002/crat.2170210407

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY