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101.
102.
103.
The nucleation of dislocations in single crystals of molybdenum and a Mo-1.5 at % Ir solid solution has been investigated
by nanoindentation. In the curve of indentation of a Berkovich indenter into the single crystals, an abrupt transition from
elastic to plastic deformation has been observed at a depth of 20–40 nm due to the nucleation of dislocations in the initially
dislocation-free region under the contact. Alloying of molybdenum by iridium results in a twofold increase in shear stresses
under which dislocations nucleated in the contact. Therefore, the solid solution impurity of iridium in molybdenum leads to
an increase not only in the plastic strain resistance (to an increase in the hardness) but also in the elastic shear stresses
under which dislocations are generated (homogeneously or heterogeneously) in the contact. The latter effect cannot be explained
only by an increase in the elastic moduli because of its smallness; however, it is determined to a large extent by a higher
degree of perfection of the solid solution crystal as compared to unalloyed molybdenum. 相似文献
104.
105.
TX Liu T Wei SE Zhu GW Wang M Jiao S Yang FL Bowles MM Olmstead AL Balch 《Journal of the American Chemical Society》2012,134(29):11956-11959
The reaction of an organic azide with an endohedral metallofullerene has been investigated for the first time. Isomeric [5,6]- and [6,6]-azafulleroids can be obtained from the thermal reaction of Sc(3)N@I(h)-C(80) with 4-isopropoxyphenyl azide, while photoirradiation leads exclusively to the [6,6]-azafulleroid. An unprecedented thermal interconversion between the two isomeric azafulleroids has also been discovered. 相似文献
106.
Yang S Troyanov SI Popov AA Krause M Dunsch L 《Journal of the American Chemical Society》2006,128(51):16733-16739
The high-yield synthesis of Dy3N@C80 (I) opens the possibility of characterizing its molecular and vibrational structures. We report on the structure determination of Dy3N@C80 (I) by X-ray crystallographic study of single crystal of Dy3N@C80.Ni(OEP).2C6H6, revealing a nearly planar Dy3N cluster encapsulated in an Ih-C80 cage. The vibrational structure of Dy3N@C80 (I) is studied by Fourier transform infrared (FTIR) and Raman spectroscopy in combination with force-field calculations. A correlation was found between the antisymmetric metal-nitrogen stretching vibration and the structure of the M3N cluster of M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm). Moreover, a stronger interaction between the encaged nitride cluster and the C80 carbon cage was found in the class II M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm) than in Sc3N@C80 (I). This study demonstrates that the cluster size plays the dominating role in the structure of the M3N cluster in M3N@C80 (I). 相似文献
107.
108.
Dysprosium-based trimetallic nitride endohedral fullerenes (clusterfullerenes)-the Dy(3)N@C(2)(n) (38 = n = 49) family-have been produced at overwhelming yields compared to the empty fullerenes for the first time. The Dy(3)N@C(2)(n) family represents the largest clusterfullerene family explored up to now, even in comparison with the Tm(3)N@C(2)(n) (38 = n = 44) family which was discovered very recently. A series of 10 Dy(3)N@C(2)(n) clusterfullerenes (39 = n = 44, 1-9) have been isolated successfully and characterized by HPLC, mass spectrometry, and UV-vis-NIR spectroscopy. The study on the HPLC elution behavior reveals that there are two isomers for Dy(3)N@C(78) and Dy(3)N@C(84). Furthermore, a third isomer of Dy(3)N@C(80) is isolated for the first time. The optimum production conditions (Dy:C = 1:15, NH(3) pressure = 20 mbar) have been determined by investigating the effects of the Dy:C ratio and NH(3) pressure on the yields of the Dy(3)N@C(2)(n) clusterfullerenes. UV-vis-NIR spectroscopic study indicates that the Dy(3)N@C(2)(n) clusterfullerenes with small cages (n = 39-41) are large band-gap (1.38 approximately 1.51 eV) materials, while the band-gaps for those with larger cages (n = 42-44) are significantly smaller (0.80 approximately 0.84 eV). 相似文献
109.
Popov AA Krause M Yang S Wong J Dunsch L 《The journal of physical chemistry. B》2007,111(13):3363-3369
Molecular structures of Dy(3)N@C(78) and Tm(3)N@C(78) clusterfullerenes are addressed by the IR and Raman vibrational spectroscopic studies and density functional theory (DFT) computations. First, extensive semiempirical calculations of 2927 isomers of C(78) hexaanions followed by DFT optimization were applied to establish their relative stability. Then, DFT calculations of a series of M(3)N@C(78) (M = Sc, Y, Lu, La) isomers were performed which have shown that the stability order of the isomers depends on the cluster size. While the Sc(3)N cluster is planar in the earlier reported Sc(3)N@C(78) (D(3)h: 24,109) clusterfullerenes, relatively large Y(3)N and Lu(3)N clusters would be forced to be pyramidal inside this cage, which would result in their destabilization. Instead, these clusters remain planar in the nonisolated pentagon rule (non-IPR) C(2): 22,010 isomer making Y(3)N@C(78) and Lu(3)N@C(78) clusterfullerenes with this cage structure the most stable ones. Finally, on the basis of a detailed analysis of their IR and Raman spectra supplemented with DFT vibrational calculations, the recently isolated Tm(3)N@C(78) and the major isomer of Dy(3)N@C(78) are assigned to the non-IPR C(2): 22,010 cage structure. A detailed assignment of their experimental and computed IR and Raman spectra is provided to support this conclusion and to exclude other cage isomers. 相似文献
110.
Yang S Chen C Jiao M Tamm NB Lanskikh MA Kemnitz E Troyanov SI 《Inorganic chemistry》2011,50(8):3766-3771
Sc(3)N@D(5h)-C(80) and Sc(3)N@I(h)-C(80) were trifluoromethylated with CF(3)I at 400 °C, affording mixtures of CF(3) derivatives. After separation with HPLC, the first multi-CF(3) derivative of Sc(3)N@D(5h)-C(80), Sc(3)N@D(5h)-C(80)(CF(3))(18), and three new isomers of Sc(3)N@I(h)-C(80)(CF(3))(14) were investigated by X-ray crystallography. The Sc(3)N@D(5h)-C(80)(CF(3))(18) molecule is characterized by a large number of double C-C bonds and benzenoid rings within the D(5h)-C(80) cage and a fully different position of the Sc(3)N unit compared to that in the pristine Sc(3)N@D(5h)-C(80). A detailed comparison of five Sc(3)N@I(h)-C(80)(CF(3))(14) isomers reveals a strong influence of the exohedral additions on the behavior of the Sc(3)N cluster inside the I(h)-C(80) cage. 相似文献