Transport properties of (NH4)2 CuCl4.2H2O low dimensional single crystals

The X-ray diffraction and Infrared (IR) spectral studies of (NH4)2CuCl4.2H2O single crystals reveals that these crystals contains tetragonal crystal structure with the unit cell dimensions of a=7.58A, c=7.95A, z=2, β=90 and two water molecules in the unit cell. The temperature dependence of thermally stimulated depolarization current (TSDC) and dc electrical conductivity (σ) studies of this two-dimensional (NH4)2CuCl4.2H2O single crystal have been carried out in 77K-300K temperature region. The TSDC thermograph shows only one sharp peak at 248K with a peak current of 130nA, which is attributed to the Maxwell-Wagner peak. The activation energy (U), relaxation time (τ) are calculated as 0.78eV and 3.44 x 10-15 s respectively. Dc electrical conductivity studies of these crystals show a first order phase transition at about 248K. (Abstract Copyright[2002], Wiley Periodicals, Inc.)