BEHAVIOR OF HYDROGEN-BONDED FERROELECTRICS KH2ASO4 AND KD2ASO4 AT HIGH-TEMPERATURES

The Raman spectra of KH2AsO4 and KD 2AsO4 ferroelectrics are recorded at various temperatures between 300 and 463 K. Firm evidence of a high temperature phase transition is found for KH2AsO4 at 413 K and for KD2AsO 4 at 453 K. The transition is shown to be of first order and nondestructive. The role of the proton dynamics in the mechanism of this transition is also evidenced. © 1980 American Institute of Physics.