Raman scattering study of temperature induced phase transition in [C8H10NO]2 [ZnCl4]

Abstract

The Raman spectra of bis (4-acetylanilinium) tetrachloridozincate single crystals were studied in the range of 100-3500 cm −1 as a function of temperature of 298 K to 398 K. The bands mainly associated with the internal modes of the ZnCl 4 anions only undergo weak changes. However, the strong evolutions of wavenumbers, widths and intensities of many lines associated with the organic cations are observed with discontinuities in the vicinity of the phase transition at 351 K. A phase transition at Tc = 351K was observed and characterized by the differential scanning calorimetry (DSC). The most important changes are observed for two lines at 3197.13 cm −1 and 3167.10 cm −1 (at room temperature) issued from asymmetric and symmetric stretching vibrations of (C-H) band and (NH 3 ) group, respectively. The spectral characteristics of these lines are analyzed and consistently described in the framework of an order-disorder model for the phase transition. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

Thermal behavior and physicochemical studies of phase transitions before the decomposition in the selenate–tellurate protonic conductor material

“…They demonstrate that there is only one type of octahedron and one type of tetrahedron that's why we observe only one maximum at 650.2 cm -1 and 824.6 cm -1 respectively at T=298K. In fact, all the bands lose their linear character around a transition temperature, the temperature of discontinuity detected at T=320K is assumed to be the temperature of the phase transition [24], which is in accordance with the DSC result. Above 330K, all the bands recover their linearity.…”

“…Therefore, the phase transition detected at T= 320K has been proven in the compound by Raman spectroscopy. In order to quantitatively analyze the evolution of Raman bands versus temperature, the position, intensity and half width of the Raman lines were deconvoluated by Labspec software using a combination of Gaussian and Lorentzian functions [24].…”

“…Effectively, at high temperature the octahedron and the tetrahedron occupy three different positions, as described in the structural study and confirmed by the entropy study. ) reveals an important change in the half width, the movement to higher frequencies at 320 K and shift up to 50 cm -1 proving the presence of the orderdisorder phase transition [24,26].…”