Preparation and physical characteristics of a lithium-beryllium-substituted fluorapatite

A lithium-beryllium-substituted fluorapatite, Li0.50Be0.25Ca4.50(PO4)3F, has been prepared by means of a high-temperature reaction between lithium beryllium fluoride, Li2BeF4, and tricalcium phosphate, Ca3(PO4)2. This material has potential application as a waste form for radioactive and toxic fluoride salts. Monitoring of the reaction progress by differential scanning calorimetry indicated that the reaction was initiated by melting of the fluoride salt and that it was fast and complete. While reactive sintering of lithium beryllium fluoride with tricalcium phosphate led to a rather porous product, melting of the reactants with subsequent solidification readily produced a substituted fluorapatite with a near-theoretical bulk density.