Monetite (CaHPO 4 ) Synthesis in Ethanol at Room Temperature

A straightforward process was developed to synthesize monetite (CaHPO 4 , dicalcium phosphate anhydrous) powders at room temperature (21°±1°C) in ethanol solutions. The process reported here constitutes an alternative to well‐publicized monetite synthesis procedures based on the dehydration of brushite (CaHPO 4 ·2H 2 O, dicalcium phosphate dihydrate) powders either in acidic, hot (70°–95°C) aqueous solutions or in drying ovens (200°–225°C). Submicrometer monetite powders were synthesized in ethanol (ethyl alcohol) solutions containing small aliquots of concentrated H 3 PO 4 (orthophosphoric acid, 85%). Precipitated CaCO 3 (calcium carbonate, calcite form) powders with submicrometer particles were simply stirred in the above solutions in glass bottles for 3 h. The starting Ca/P molar ratio in the synthesis bottles was 0.50. Monetite powders obtained with a stacked‐nanosheets particle texture did not contain any unreacted CaCO 3 . Monetite powders were also found to have the ability to completely transform into apatitic (apatite‐like) calcium phosphate powders when soaked in calcium‐containing saline solutions (i.e., 142 mM Na + , 5 mM K + , and 50 mM Ca 2+ in water) for 6 days at 37°C.