GROWTH OF ALPHA-PBF2 SINGLE-CRYSTALS FROM AQUEOUS-SOLUTIONS OF INORGANIC ACIDS

Growth of alpha-PbF2 crystals in 0.28M perchloric acid is described. T he choice was based on an analysis of equilibria with the participatio n of fluoride ions and investigations of the solubility of lead fluori de in aqueous solutions. The enthalpy of dissolution of alpha-PbF2 in 0.28M perchloric acid is 1.6 kJ/mol, which is close to the value for p ure water (2.4 kJ/mol). Orthorhombic lead fluoride single crystals wer e grown at spontaneous crystallization by a slow cooling method in the shape of plates (3x3x0.1 mm(3)) or prisms (4x1.5x0.2 mm(3)), dependin g on the cooling rate. alpha-PbF2 was grown on a seed crystal. The gro wn layer of about 1 mm in thickness has no visual inclusions and crack s.