998 resultados para DY-3
Resumo:
"S 3 kartinami"--N. I. Berezin. Russkia knizhnyia riedkosti, 1902, no.562."
Resumo:
t. 1. 1612-1628.--t. 3. S 1645 po 1676 g.--t. 4. S 1676 po 1701 g.
Resumo:
Doped ceria (CeO2) compounds are fluorite-type oxides that show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, considerable interest has been shown in application of these materials for low (500 degrees-650 degrees C) temperature operation of solid oxide fuel cells (SOFCs). To improve the conductivity in dysprosium (Dy) doped CeO2, nano-size round shape particles were prepared using a coprecipitation method. The dense sintered bodies with small grain sizes (< 300 nm) were fabricated using a combined process of spark plasma sintering (SPS) and conventional sintering (CS). Dy-doped CeO2 sintered body with large grains (1.1 mu m) had large micro-domains. The conductivity in the sintered body was low (-3.2 S/cm at 500 degrees C). On the other hand, the conductivity in the specimens obtained by the combined process was considerably improved. The micro-domain size in the grain was minimized using the present process. It is concluded that the enhancement of conductivity in dense specimens produced by the combined process (SPS+CS) is attributable to the microstructural changes within the grains.
Resumo:
257 p.
Resumo:
A low temperature synthesis method based on the decomposition of urea at 90C in water has been developed to synthesise fraipontite. This material is characterised by a basal reflection 001 at 7.44 . The trioctahedral nature of the fraipontite is shown by the presence of a 06l band around 1.54 , while a minor band around 1.51 indicates some cation ordering between Zn and Al resulting in Al-rich areas with a more dioctahedral nature. TEM and IR indicate that no separate kaolinite phase is present. An increase in the Al content however, did result in the formation of some SiO2 in the form of quartz. Minor impurities of carbonate salts were observed during the synthesis caused by to the formation of CO32- during the decomposition of urea.
Resumo:
The infrared (IR) spectroscopic data and Raman spectroscopic properties for a series of 13 pinwheel-like homoleptic bis(phthalocyaninato) rare earth complexes M[Pc(-OC5H11)4]2 [M = Y and PrLu except Pm; H2Pc(-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine] have been collected and comparatively studied. Both the IR and Raman spectra for M[Pc(-OC5H11)4]2 are more complicated than those of homoleptic bis(phthalocyaninato) rare earth analogues, namely M(Pc)2 and M[Pc(OC8H17)8]2, but resemble (for IR) or are a bit more complicated (for Raman) than those of heteroleptic counterparts M(Pc)[Pc(-OC5H11)4], revealing the decreased molecular symmetry of these double-decker compounds, namely S8. Except for the obvious splitting of the isoindole breathing band at 11101123 cm1, the IR spectra of M[Pc(-OC5H11)4]2 are quite similar to those of corresponding M(Pc)[Pc(-OC5H11)4] and therefore are similarly assigned. With laser excitation at 633 nm, Raman bands derived from isoindole ring and aza stretchings in the range of 13001600 cm1 are selectively intensified. The IR spectra reveal that the frequencies of pyrrole stretching and pyrrole stretching coupled with the symmetrical CH bending of CH3 groups are sensitive to the rare earth ionic size, while the Raman technique shows that the bands due to the isoindole stretchings and the coupled pyrrole and aza stretchings are similarly affected. Nevertheless, the phthalocyanine monoanion radical Pc IR marker band of bis(phthalocyaninato) complexes involving the same rare earth ion is found to shift to lower energy in the order M(Pc)2 > M(Pc)[Pc(-OC5H11)4] > M[Pc(-OC5H11)4]2, revealing the weakened interaction between the two phthalocyanine rings in the same order.
