Effect of a periodic temperature variation on the properties of TlGaSe2 crystals

It is shown experimentally that thermal cycling of TlGaSe2 crystals does not result in appreciable disruption of the stacking of layered units along the C axis. The integrated intensities of (310), (221) reflections from this crystal change anomalously with temperature, These changes relax to their original values at room temperature over times in excess of 17 hours, which coincides with the time for recovery of the original properties of TlGaSe2 samples investigated previously. Such behavior of the integrated intensity is connected with thermal migration of Tl+ ions over possible crystallographic sites within a unit cell. (C) 1997 American Institute of Physics.