Deuterium impurities and the Rayleigh central peak in hydrogen-bonded ferroelectrics

Results of a mean-field treatment of deuterium impurities in hydrogen-bonded ferroelectrics are compared with observations of the critical central peak in potassium dihydrogen phosphate. The natural abundance of deuterium accounts quantiatively for the relative strength and temperature dependence of the peak. Its slow dynamics and the absence of a similar feature in cesium dihydrogen arsenate are commented on. © 1977 The American Physical Society.