THE ROLE OF AMMONIUM-IONS IN THE FREEZING DYNAMICS OF MIXED KADP CRYSTALS

The formation of ordered and disordered phases in mixed crystals K1-x( NH4)(x)H2PO4 in wide temperature and concentration ranges are investig ated by Raman spectroscopy method. Polarizational measurements of inte nsities, frequencies and half-withds of librational and internal vibra tional modes of ammonium ions are carried out. The analysis of these r esults proves that reorientation of the ammonium ions with the fixatio n of their positions takes place below the temperature of onset of fre ezing (T-m). This temperature is about 50 K higher than that of proton glass formation at al relevant concentrations. The activation energie s of the reorientation processes are determined.