EFFECT OF GAMMA-IRRADIATION ON THE HEAT-CAPACITY OF RB2ZNBR4 IN THE VICINITY OF PHASE-TRANSITIONS

Heat capacity of Rb2ZnBr4 as a function of gamma irradiation dose has been measured within the 85-300 K range by the adiabatic calorimeter t echnique. It is shown that, as the irradiation dose increases, the hea t capacity peak in the vicinity of the incommensurate-commensurate fir st-order phase transition (PT) decreases, and the transition temperatu re T-c increases. The heal capacity peak in the region of the second-o rder PT at T-3 = 112 K does not depend on gamma irradiation, both in m agnitude and in position, just as the heat capacity throughout the rem ainder of the temperature range studied. (C) 1998 American Institute o f Physics.