Structural instabilities in the (TEA)₂m Cl₄crystalline family: A DSC study

Synthesis, Calorimetric Study, Infrared Spectroscopy And Crystal Structure Investigation Of β-[Tetraethylammonium Tetramethylammonium Tetrachlorozincate(II)] [β]-[(C2h5)4N][(Ch3)4N]Zncl4

“…ZnCl 4 tetrahedra present a C 1 punctual symmetry with geometrical features similar to those commonly observed [22 -24]. The Zn-Cl distances vary between 2.265 (2) [12]. The α and β forms were prepared starting from the same mixture of components in aqueous solution.…”

“…The atomic arrangement in the α and β form is similar. It consists of alternate organic-inorganic layers (TMA/ZnCl 4 ) and organic sheets (TEA) both parallel [12]. Disordered atoms are represented by black circles with reduced radii.…”

“…The crystals with the tetraethylammonium cation, [N(C 2 H 5 ) 4 ] 2 MCl 4 , show at r. t. the tetragonal symmetry P4 2 /nmc with similar cell parameters [10]. A differential scanning calorimetry study showed two transitions for [N(C 2 H 5 ) 4 ] 2 ZnCl 4 [11]. The crystal structure of α-[N(C 2 4 by means of differential thermal analysis, IR spectroscopy and X-ray diffraction.…”

Structure of TEA2ZnCl4crystal surfaces studied by AFM

“…In the low-temperature phase the TEA þ ions are ordered and only their methyl groups perform rotations. The first order of the phase transitions has been confirmed by specific heat anomalies [1,6]. The crystal symmetry decreases from the tetragonal 4/mmm in the high-temperature phase to orthorhombic mmm, accompanied with a doubling of the elementary cell, so the low-temperature phase should be improper ferroelastic.…”

Thermal and FTIR spectral characterisation of diammonium tetrachlorocobaltate(II) monohydrate crystals

“…At room temperatures, the tetraethyl group in [N(C 2 H 5 ) 4 ] 2 BX 4 compounds are disordered and become ordered at low temperature. Caetano et al [8] analysed the sequence of structural phase transitions and changes which occur in the compounds [N(C 2 H 5 ) 4 ] 2 MCl 4 where M = Cu, Zn, Ni, Co, Cd and Hg. It is reported that the compound, [N(CH 3 ) 4 ] 2 CoCl 4 shows ferroelectric properties between 4.6 and 7.1°C [9].…”