Mossbauer investigation of the crystallographic phase transition in Cs2FeCl5.H2O

Abstract

The antiferromagnetic salt Cs2FeCl5.H2O is observed to undergo a crystallographic phase transition at TC=151.5+or-0.5 K in which the electric field gradient tensor becomes symmetric in the high-temperature phase. The order of this phase change is discussed. At temperatures below TC the quadrupole splitting has a saturation value of 0.295+or-0.005 mm s-1. Values of the Debye temperature for the material were obtained by relating the temperature variation of the spectrum centre shift and resonant absorption area to the second-order Doppler shift and the recoil-free fraction respectively.