GROWTH OF POTASSIUM DIHYDROGEN PHOSPHATE CRYSTALS NUCLEATED IN THE PRESENCE OF ALUMINUM(III)

The effects of aluminium ions on the nucleation and crystal growth kinetics of potassium dihydrogen phosphate (KDP) are reported: primary nucleation is reduced by the presence of aluminium; crystal growth is reduced and sometimes completely inhibited; crystal habit is also strongly affected. ICPS and SIMS measurements of the aluminium content in the crystal are performed. Growth kinetics are determined: in the absence of impurities, a second order law is found. An new model of competitive integration of impurities and normal growth units into the KDP lattice leads to a qualitative and quantitative interpretation of the impurity effect.