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F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,4(10):763-768
The diagram of the ternary system Mg2+/Cl−, SO4 2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4 2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C. 相似文献
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The isoplethic sections in the diagram of the quaternary system Na+ , Mg2+ //Cl– , SO2– 4 –H2 O were established at 25 and 30oC by analytical and conductometric measurements. Three compounds can be observed in the isoplethic sections: NaCl, Na2 SO4 and MgNa2 (SO4 )2 4 H2 O. Seven fields are determined, relating to the precipitation of one, two or three salts. The solubility range of MgNa2 (SO4 )2 4 H2 O is wide, while the liquidus curve of Na2 SO4 is very short. The compositions, expressed in Jänecke coordinates, at the eutonic and peritonic points, respectively, were: 42.70% Cl– and 745% H2 O; 79.47% Cl– and 787% H2 O; 71.6% Cl– and 744% H2 O at 25°C; and 48.80% Cl– and 715% H2 O; 80.20% Cl– and 778% H2 O; 70.14% Cl– and 707% H2 O at 30°C. 相似文献
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Zayani Jaafar Othman Adel Matoussi Filippo Fabbri Francesca Rossi Giancarlo Salviati 《Applied Physics A: Materials Science & Processing》2014,116(3):1501-1509
This paper reports structural, optical and cathodoluminescence characterizations of sintered Zn1?x Mg x O composite materials. The effects of MgO composition on these film properties have been analyzed. X-ray diffraction (XRD) confirms that all composites are polycrystalline with prominent hexagonal wurtzite structure along two preferred orientations (002) and (101) for the crystallite growth. Above doping content x = 10 %, the formation of the hexagonal ZnMgO alloy phase and the segregation of the cubic MgO phase start. From reflectance and absorption measurements, we determined the band gap energy which tends to increase from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein–Moss effect which causes a significant increase of electron concentration (2.89 × 1018?5.19 × 1020 cm?3). The luminescent properties of the Zn1?x Mg x O pellets are studied by cathodoluminescence (CL) at room and liquid nitrogen temperatures under different electron beam excitations. At room temperature, the CL spectra of the Zn1?x Mg x O composites exhibit a dominant broad yellow-green light band at 2.38 eV and two ultraviolet emission peaks at 3.24 and 3.45 eV corresponding to the luminescence of the hexagonal ZnO and ZnMgO structures, respectively. For the doped ZnO samples, it reveals also new red peaks at 1.72 and 1.77 eV assigned to impurities’ emissions. However, the CL spectra recorded at 77 K show the presence of excitonic emission peaks related to recombination of free exciton (X A), neutral donor-bound excitons (D0X) and their phonon replicas. The CL intensity and energy position of the green, red and ultraviolet emission peaks are found to depend strongly on the MgO doping content. The CL intensity of the UV and red emissions is more enhanced than the green light when the MgO content increases. CL imaging analysis shows that the repartition of the emitting centers in Zn1?x Mg x O composites is intimately connected to the film composition and surface morphology. 相似文献
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C. Fuentes R. Haverkamp J. Y. Parlange W. Brutsaert K. Zayani G. Vachaud 《Transport in Porous Media》1991,6(4):445-449
The constraints on the different fitting parameters used in the water-retention equations of Brooks and Corey, Brutsaert, and Van Genuchten are analyzed. It is shown that in the dry part of the h() curve all three equations might break down for clay soils when the fitting parameters are calculated by a best fit over observed field data. In that case, application of the h() equations for water transfer dealing with the very dry parts of the water retention curve can lead to erroneous results and must be limited to the range of water contents of the original data set. 相似文献
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Rabti Amal Zayani Riham Meftah Marwa Salhi Imed Raouafi Noureddine 《Mikrochimica acta》2020,187(11):1-24
Microchimica Acta - This review (with 106 references) summarizes the latest progress in the synthesis, properties and biomedical applications of gold nanotubes (AuNTs). Following an introduction... 相似文献
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