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81.
E. Černošková R. Todorov Z. Černošek J. Holubová L. Beneš 《Journal of Thermal Analysis and Calorimetry》2014,118(1):105-110
The amorphous Sb2Se3 film with a thickness ~0.9 µm was prepared by thermal evaporation and its composition was confirmed using an energy-dispersive X-ray analysis. The amorphous state was checked by an X-ray diffraction analysis. The optical gap E g opt was determined to be 1.32 eV. The glass transition temperature could not be found by either a differential scanning calorimetry or a thermomechanical analysis. The film was crystallized and characterized using the quasi-isothermal method. The temperature dependence of the isobaric heat capacity was raised monotonously and no drop over the course of the crystallization was observed. The temperature-modulated thermomechanical analysis determined a temperature T = 133 °C which can be assumed to be the temperature of the structural reorganization beginning. Raman spectra of amorphous Sb2Se3 revealed that the vibrations of both the amorphous and crystalline phase are close to one other. Raman scattering revealed that both the short and the medium-range order of amorphous and crystalline phases are similar. 相似文献
82.
The Assembly‐Disassembly‐Organization‐Reassembly Mechanism for 3D‐2D‐3D Transformation of Germanosilicate IWW Zeolite 下载免费PDF全文
Pavla Chlubná‐Eliášová Yuyang Tian Dr. Ana B. Pinar Dr. Martin Kubů Prof. Jiří Čejka Prof. Russell E. Morris 《Angewandte Chemie (International ed. in English)》2014,53(27):7048-7052
Hydrolysis of germanosilicate zeolites with the IWW structure shows two different outcomes depending on the composition of the starting materials. Ge‐rich IWW (Si/Ge=3.1) is disassembled into a layered material (IPC‐5P), which can be reassembled into an almost pure silica IWW on treatment with diethoxydimethylsilane. Ge‐poor IWW (Si/Ge=6.4) is not completely disassembled on hydrolysis, but retains some 3D connectivity. This structure can be reassembled into IWW by incorporation of Al to fill the defects left when the Ge is removed. 相似文献
83.
Dr. Paul S. Wheatley Dr. Pavla Chlubná‐Eliášová Dr. Heather Greer Prof. Wuzong Zhou Dr. Valerie R. Seymour Dr. Daniel M. Dawson Prof. Sharon E. Ashbrook Dr. Ana B. Pinar Dr. Lynne B. McCusker Dr. Maksym Opanasenko Prof. Jiří Čejka Prof. Russell E. Morris 《Angewandte Chemie (International ed. in English)》2014,53(48):13210-13214
Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure‐directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8‐rings all the way to extra‐large pores consisting of 14‐rings. 相似文献
84.
Vladimír Mastihuba Pavel Čepec Silvia Vlčková Erika Farkašová Mária Mastihubová Pavel Bobal 《Chemical Papers》2014,68(6):745-750
Two lipases, Novozyme 435 (lipase B from Candida Antarctica) and Lipozyme TL IM (Thermomyces lanuginosus) were used successfully for the kinetic resolution of racemic 1-(2-furyl)-3-pentanol, the key intermediate in synthesis of the bark beetle pheromone, chalcogran. The desired S-(+)-enantiomer was prepared in enantiomeric excesses higher than 98 % and with yields of 26.3 % and 32.5 %, respectively. Methyl tert-butyl ether and vinyl acetate were found to be the best reaction media and the acetyl donor to achieve fast and effective resolution. 相似文献
85.
86.
Vapor pressures of six pentanols, 2-methyl-1-butanol (CAS Registry Number 137-32-6), 2-methyl-2-butanol (CAS Registry Number 75-85-4), 3-methyl-1-butanol (CAS Registry Number 123-51-3), 3-methyl-2-butanol (CAS Registry Number 598-75-4), 2-pentanol (CAS Registry Number 6032-29-7) and 3-pentanol (CAS Registry Number 584-02-1), were measured by the precision ebulliometry over an approximate pressure range from 9 to 99 kPa. The absolute uncertainties in pressure and temperature are estimated to be less than or equal to 7 Pa and 0.02 K, respectively. The results are represented by the Antoine equation and compared with available literature data. 相似文献
87.
88.
Published in Lietuvos Matematikos Rinkinys, Vol. 33, No. 1, pp. 16–29, January–March, 1993. 相似文献
89.
The Hardy correction in the heat current operator is generalized to the case of non-zero electron-phonon coupling constantg. It is then shown that not only the lowest (minus first) order but also the fist order contribution ing to the thermoelectric power of amorphous semiconductors in the hopping regime disappears. Consequently, since the lowest (zero) order contribution to the thermoelectric effects in the magnetic field yields no Nernst-Ettingshausen effect in these materials, the last effect is of the second order ing, at least. 相似文献
90.
V. Čápek 《Czechoslovak Journal of Physics》1974,24(12):1362-1368
The assumption that the thermoelectric power of amorphous elemental semiconductors remains constant (in the hopping regime) down to zero temperature (which accords with some experiments on e.g. amorphous Ge performed above 100 K) is shown to be incompatible with the lowest order single-phonon hopping theory until the spatial interlevel correlations are taken into account. 相似文献