The phase transition sequence in tetramethylammonium cadmium chloride (TMCC):

Abstract

The structural phase transitions in [N(CH 3 ) 4 ]CdCl 3 were investigated by means of adiabatic calorimetry and thermal expansion measurements. Two phase transitions have been studied on cooling and on heating at about 104 K and 118 K. The shapes of the observed specific heat anomalies, as well as the existence of thermal hysteresis, confirm the first-order character previously assigned to these phase transitions. From the experimental data and the harmonic specific heat obtained from the known frequencies of the vibrational modes, a calculation of the Grüneisen parameter as a function of the temperature is also given. Finally, the suitability of different Landau potentials for the two phase transitions is briefly discussed.

Preparation and characterization of organic–inorganic hybrid compound [N(C4H9)4]2Cu2Cl6

“…Recently, a considerable effort has been made both in experimental and theoretical studies in order to achieve an understanding of the dynamical behavior of these groups, since they are mainly responsible for the order-disorder phase transitions observed. Most of the members of this family exhibit a structural phase transition with decreasing temperature [7,8]. Up to now, the molecular motions of the organic cations and phase transitions have been studied for several compounds [9][10][11][12][13] In this aim, the present work is devoted to IR, Raman, X-rays powder, differential scanning calorimetry (DSC), DTA-TGA analysis and impedance spectroscopy on a new sample Bis(tetrabutylammonium) hexachlorodicuprate (II), [N(C 4 H 9 ) 4 ] 2 Cu 2 Cl 6 .…”

Electrical properties and equivalent circuit of trimethylammonium monobromodichloromercurate

“…The space between chains is occupied by [(CH 3 ) x NH 4−x ] + cation [1][2][3][4][5][6][7][8]. Many of these structures show successive phase transitions, mainly due to order-disorder of the substituted ammonium group.…”

14N NMR study of the domain structure of tetramethylammonium cadmium chloride (TMCC)

“…The room temperature phase I of TMCC and of TMMC (space group P6 3 /m and Z = 2) is found to be derived from phase I′ by a 14 N NMR study of tetramethylammonium cadmium chloride rotation of the octahedra chains about the c-axis [16]. For TMCC two structural first order phase transitions at 118 and 104 K have been observed [13,15,16,19,20]. The first phase transition (118 K) of TMCC connects phase I to a monoclinic phase (ferro-elastic phase) with a space group P2 1 /m (Z = 2).…”