EFFECT OF DEFECTS INDUCED BY DOPING AND FAST-NEUTRON IRRADIATION ON THE THERMAL-PROPERTIES OF LITHIUM AMMONIUM-SULFATE CRYSTALS

Structural defects were introduced in lithium ammonium sulphate crysta ls (LAS) either in the process of crystal growth (in the form of forei gn ions) or by neutron irradiation. The effect of such defects on the thermal properties of LAS crystals was studied in the temperature rang e 300-500 K. It was assumed that the doped LAS crystals are composed o f a two-phase system having different thermal parameters in each phase . The specific heat at constant pressure, C(p), of irradiated samples was found to decrease with increasing irradiation doses. The thermal e xpansion of LAS crystals was found to be dependent on neutron irradiat ion, and was attributed to two processes: the release of new species a nd the trapping process.