Analysis of high temperature phases transition
of (C2H5NH3)2BaCl4 doped by copper
F. Ben Nasr, K. Guidara*, M. Gargouri
Laboratoire de l'état Solide de la Faculté des Sciences de Sfax,
Route de Soukra, 3018 BP 802 Sfax, Tunisie
* Corresponding author. E-mail :Kamel.Guidara@francite.com
Received : 09 May 2002; revised version accepted : 30 July 2002
Raman spectroscopy in the low frequency range (15-200 cm-1 ) and differential scanning calorimetry of polycrystalline samples of (C2H5NH3)2BaCl4 doped by copper were performed in the high temperature range 300-425K. These techniques confirmed the availability of three first order transitions I’®g’® b’® a’ respectively at T'1 = 362.7K(DH1 = 70.79KJ/mol), T'2= 395.9K(DH2 = 49.72KJ/mol) and T'3 = 406.1K (DH3 = 4.68KJ/mol). Thermal analysis suggests structural changes for the first transition, the others transitions are governed by displacive mechanisms involving deformations of MCl6 octahedra. The last temperature seams to be a plastic phase.
Keywords: (C2H5NH3)2Ba0.95Cu0.05Cl4; Phase transition plastic phase.