Nucleation of struvite (MgNH4PO4 · 6 H2O) single crystals and aggregates

The conditions (concentration and pH) for preparation of single crystals of struvite at 25 °C from ammoniacal solutions equimolar with respect to magnesium and phosphate ions are given. The limits are found above which crystal aggregates (twins or dendrites) precipitate as dominant morphology. The mechanisms of nucleation are discussed and the interfacial tension between crystals and solution is evaluated.