Temperature study of [N(C3H7)4]2Cd2Cl6 by thermal analysis, Raman scattering, and X-ray powder diffraction: Evidence of phase transitions

✍ Scribed by N. Hannachi; A. Bulou; C. Chassenieux; K. Guidara; F. Hlel

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 865 KB
• Volume: 390
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/j.physa.2011.03.020

✦ Synopsis

The phase transitions of [N(C 3 H 7 ) 4 ] 2 Cd 2 Cl 6 have been evidenced by differential scanning calorimetry (DSC), and the different phases have been studied by Raman scattering on single crystals, in the frequency range 50-3900 cm -1 for temperatures ranging between 294 and 451 K. On heating, two reversible phase transitions are observed at T 1 = 321.5 K (weakly first order, with 1.2 K hysteresis) and T 2 = 323.6 K (second order), and a strongly first-order transition occurs in the vicinity of 448 K (T 3 ), with breaking of the crystal and decrease of the temperature of transition for successive temperature cycles.

The temperature dependence of the Raman line shifts ν, the half-width ∆ν, and the relative intensities show weak singularities in the vicinity of T 1 and T 2 and marked effects on approaching T 3 . The X-ray powder diffraction patterns at room temperature prior to and after the T 3 phase transition show that it is irreversible, although the diffractograms look qualitatively very similar.