Growth of LiH2PO4 single crystals from phosphate solutions

• LiH2PO4 single crystals were grown from aqueous solutions of orthophosphoric acid.
• The solubility of LDP was found to diminish with the rise of the acid concentration.
• The analysis of the growth conditions of LDP crystals was performed.
• The habitus of the crystals changes with the increase of the acid concentration.
• The planes of the pyramid {111}, the dome {011} and the pedestal {001-} widen.

Lithium dihydrogen phosphate (LiH2PO4, LDP) single crystals were grown from aqueous solutions of orthophosphoric acid. The influence of the concentration of the acid in the mother liquor on the solubility of LDP crystals and the conditions of their crystallization, was studied. The change of LDP solubility with the rise of the temperature was found to be not higher than 5 mass%, irrespective of the acid concentration. The solubility diminished with the increase of the acid concentration in the mother liquor.The conditions of the growth of LDP crystals were analyzed from the viewpoint of the method of creation of the solution supersaturation, e.g. change of the acid concentration or evaporation of the solvent. The latter method is most optimal for the growth of LDP crystals from aqueous solutions of orthophosphoric acid. The habitus of the crystals was established to change with the rise of the acid concentration in the solution: the growth of the faces of the pyramid {111-} and the dome {011-} is suppressed, whereas the face of the pedestal {001-} continues to grow. The model of the influence of hydrogen bonds on the habitus of the crystals was considered.