ISSN:0232-1300    

DOI:10.1002/crat.2170280802

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractWet purification of crude MgSO3· 6 H2O obtained at flue gases desulphurization is based on its dissolution, separation of solid ash followed by crystallization of a clear supersaturated solution. The stability of supersaturated solutions during ash separation represents a requisite condition for realization of this process. The stability of agitated supersaturated solutions containing from 5 to 8 wt% of MgSO3is assessed in the temperature range from 80° to 95 °C based on experimentally determined induction period of crystallization,tind, and desupersaturation curves. Time necessary for complete dissolution of MgSO3· 6 H2O at the studied conditions,tD, is also determined. A plot of (tind–tD) versus solution initial supersaturation facilitates selection of suitable processing conditions for the wet purific

ISSN:0232-1300    

DOI:10.1002/crat.2170280803

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe growth features of FeCr2S4spinel single crystals prepared by chemical vapour transport were studied by means of scanning electron microscopy, transmission electron microscopy, high resolution electron microscopy, electron diffraction and X‐ray analysis. Our results indicate that the epitaxial growth of the new phases FeCr7S12and FeCr8S12, both based on the NiAs structure, can essentially inhibit the growth of large FeCr2S4spinel single crystals in the octahedral habit. The new phases are fully characterised and the effects of defect ordering in these new phases are also reporte

ISSN:0232-1300    

DOI:10.1002/crat.2170280804

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0232-1300    

DOI:10.1002/crat.2170280805

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractEffect of crystal growth rate on polytypism has been explained using STGR model. It has been suggested that during the process of growth, polytypes are formed from a suitable combination of basic units in accordance with the rate of growth. At a slower rate the most probable polytype is predicted to be different from the one at faster rate.

ISSN:0232-1300    

DOI:10.1002/crat.2170280806

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Graded Neutral Gel Technique (GNGT) of controlling the nucleation was extended to the gel growth of crystals by a solubility reduction process. Successful and interesting results were obtained in five systems, of the six tried. Attainment of morphological stability, growth around the axial region, and elimination of the growth of pseudo‐structures and salting out effect were the salient features observe

ISSN:0232-1300    

DOI:10.1002/crat.2170280807

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe non‐uniform doping profiles may prove useful for some semiconductor devices instead of the uniform ones. In the paper the doping mechanism of silicon epitaxial layers in the SiCl4H2PH3system is investigated. The epitaxial doping profile simulation program is developed based on the Wong‐Reif trapping model and taking into account also the difference between dopant profile and the charge carrier profile. The three unknown parameters of the Wong‐Reif model are found with the aid of the simulatio

ISSN:0232-1300    

DOI:10.1002/crat.2170280808

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractAn investigation of the Co oxides formation and distribution dependent on preparation conditions during electrodeposition of hcp Co‐based films with perpendicular magnetic anisotropy has been made. It has been shown that the [100] oriented columnar crystallites promote some regularity in impurity distribution and orientation in the film plane, whereas the [001]oriented ones‐ non‐regular distribution. Such a behaviour is associated with the difference in the impurity incorporation for these two cases: preferably crystalline and intergranular, respectively, and atomic bonds saturation, and influence on the mechanical and magnetic properties of the investigated

ISSN:0232-1300    

DOI:10.1002/crat.2170280809

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractLead titanate powders and thin films were prepared by the sol‐gel process of metal alkoxide solutions and solvents. From DSC measurements, phase transition temperature of crystallized PbTiO3powders was obtained at about 484 °C. From XRD investigation, it was confirmed that the tetragonal phase of polycrystalline PbTiO3thin films is formed by coating of concentrated solution on all of the substrates we used after heat treatment above 500 °C.It was found by SEM and ellipsometric analysis that the thin film coated with 0.25 M concentrated solutions once had an average thickness of about 720 Å. Surfaces of thin films were crack‐free, uniform, and its average grain size investigated by SEM was 0.6–0.8 μm. Band gap energy of PbTiO3thin film coated on the Al2O3(2243) substrate was 3.45 eV, which is assumed to be due to the direct band to band transition. Dielectric constant (ϵ) and dielectric loss (tan δ) of PbTiO3thin film amounted to 60–70 and 0.01–0.02 in the region of 10 kHz ∼ 1 MHz at room temperature, respectively, and transition temperature was 486 °C at 1 MHz. From the hysteresis loop of PbTiO3thin film, spontaneous polarization of 12 μC/cm2and coercive filed of 45

ISSN:0232-1300    

DOI:10.1002/crat.2170280810

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractElemental Bi, Te, and Ge of 5N purity were used to prepare Bi2Te3(GeTe) single crystals with germanium content varying from 0 up to 2.3 × 1021cm−3. The samples were characterized by reflectivity measurements in the plasma resonance frequency range and by measurements of the electrical conductivity. Germanium content in the samples was determined by means of energy dispersive analysis. The reflectivity spectra were interpreted on the basis of the Drude‐Zener theory in the aim to obtain information on the concentration of the free carriers in the samples. It was found that Ge atoms in the Be2Te3crystal lattice behave as acceptors. A comparison of the hole concentration with the amount of germanium built into the crystal lattice revealed that only about 1/100 of the total number of Ge atoms act as acceptors. This effect is explained by two different ways of incorporation of Ge atoms into the Bi2Te3lattice, viz: the formation of substitutional Ge'Bidefects acting as acceptors and the formation of seven‐layer‐lamellae of the TeBiTeGeTeBiTe composition, which corresponds to the s

ISSN:0232-1300    

DOI:10.1002/crat.2170280811

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY