semiempirical parameter
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2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Hela Ferjani ◽  
Habib Boughzala

The organic-inorganic hybrid compound (C13H28N2) BiCl5 was synthesized by solvothermal method. The crystal structure was solved by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system space group Cmc21 with a=15.826(4) Å, b=18.746(6) Å, c=7.470(3) Å, and Z=4. The crystal structure was refined down to R=0.019. It consists of corrugated layers of [BiCl5]2− chains, separated by organic [H2TMDP]2+ cations (TMDP=1,3-Bis(4-piperidyl)propane = C13H26N2). The crystal cohesion is achieved by hydrogen bonds N–H⋯Cl joining the organic and inorganic layers. The influence of the organic cations' flexibility is discussed. Raman and infrared spectra of the title compound were recorded in the range of 50–400 and 400–4000 cm−1, respectively. Semiempirical parameter model three (PM3) method has been performed to derive the calculated IR spectrum. The crystal shape morphology was simulated using the Bravais-Friedel and Donnay-Harker model.


1996 ◽  
Vol 439 ◽  
Author(s):  
L. M. Wang ◽  
S. X. Wang ◽  
W. L. Gong ◽  
R. C. Ewing

AbstractIon-beam-induced amorphization of a wide variety of ceramic materials has been investigated using in situ TEM at the HVEM-Tandem Facility at Argonne National Laboratory with 1.5 MeV Kr+ or Xe+ ions at temperatures between 20 to 1000 K. The critical amorphization temperatures and the activation energies associated with the expitaxial recovery of displacement cascades during irradiation have been determined from the temperature dependence of the critical amorphization dose. The results for phases in the A12 O3-MgO-SiO2 system suggested a parallel in the kinetics between ion-beam-induced amorphization and glass formation. Based on a cascade quenching model, a semiempirical parameter, S, which can easily be calculated from both structural and chemical parameters of a material, has been developed to predict the susceptibility of ceramics to amorphization. The critical amorphization temperature, above which irradiationinduced amorphization cannot be completed, is closely related to the glass transition temperature. The ratio between glass transition and melting temperatures can also be used to predict the susceptibility of a ceramic material to amorphization, equivalent to the Debye temperature criterion.


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