Structural changes in tetraethylammonium copper chloride

Among A2BX4 compounds, those obtained with A as the tetraethylammonium group (C2H5)4N are tetragonal (in most of cases with P42/nmc — (D154k) in their high temperature phase. The copper compound presented here is particularly interesting: it transforms in a moist atmosphere to the hydrated compound (TEA)2CuCL4 O.S H2O of different structural organisation, and it exhibits two structural phase transitions: one, to an orthorhombic phase of symmetry (Pnna — D62h), is improper ferroelastic of an order-disorder type. The second occurs at lower temperature, is between phases of same symmetry and is isostructural-like. Moreover, the compound is a good candidate for the appearance of different glassy states.

Keywords:

• Ferroelastic
• order-disorder
• structure
• isostructural transitions
• tetraethylammonium copper chloride