Corroboration of an intermediate phase transition in CsH2PO4 by Brillouin spectroscopy between room temperature and the superionic phase transition

An investigation of elastic properties of CsH2PO4 by Brillouin spectroscopy has been performed between room temperature and the superionic transition, which takes place near 230 degreesC. For every elastic constant under stud y a slight but unambiguous change of slope is found around 120 degreesC. Th e results are discussed in the light of other experimental ones, in particu lar those related to sample dehydration which could suggest the absence of any phase transition above room temperature, as recently claimed. It is con cluded that the Brillouin results corroborate the existence of a polymorphi c transition near 120 degreesC. (C) 2001 Elsevier Science Ltd. All rights r eserved.