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21.
Sbai K. Atibi A. Charaf A. Radid M. Jouini A. 《Journal of Thermal Analysis and Calorimetry》2002,69(2):627-645
We have studied the dehydration and the calcination under atmospheric pressure of cyclotriphosphate tetrahydrate of nickel and sodium, NiNa4(P3O9)2·6H2O, between 25 and 700°C by thermal analyses (TG, DTA) infrared spectrometry and X-ray diffraction. This study allows us the identification and the crystallographic characterization of a new phase, NiNa4(PO3)6, obtained between 350 and 450°C. NiNa4(PO3)6 crystallizes in the triclinic system, P–1, with the following unit cell parameters a=6.157(3) Å, b=6.820(6) Å, c=10.918(6) Å, =80.21(5)°, =97.80(9)°, =113.49(3)°, V=409.8 Å3, Z=1, M(19)=25 and F(19)=48 (0.0095; 42). The calcination of NiNa4(PO3)6, between 500 and 600°C, leads to a mixture of long-chain polyphosphates NiNa(PO3)3 and NaPO3. The kinetic characteristics of the dehydration of NiNa4(P3O9)2·6H2O were determined and discussed. The vibrational spectrum of the title compound, NiNa4(P3O9)2·6H2O, was interpreted in the domain of the stretching vibrations of the P3O9 rings, on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P3O9 ring with D3h symmetry.
This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
22.
Sbai K Rahmani A Chadli H Bantignies JL Hermet P Sauvajol JL 《The journal of physical chemistry. B》2006,110(25):12388-12393
By using the spectral moments method, we calculate the infrared spectra of chiral and achiral single-walled carbon nanotubes (SWCNTs) of different diameters and lengths. We show that the number of the infrared modes, their frequencies, and intensities depend on the length and chirality of the nanotubes. Furthermore, the dependence of the infrared spectrum as a function of the size of the SWCNT bundle is analyzed. These predictions are useful to interpret the experimental infrared spectra of SWCNTs. 相似文献