Amorphous calcium barium monophosphate and its dehydration in air at room temperature

The change in the state of chemical bonds during dehydration of amorphous calcium barium monophosphate was studied. The monophosphate was obtained by precipitation from an aqueous phosphate solution under the action of a binary solution containing simultaneously calcium and barium chlorides in the atomic ratio Ba/Ca ～0.2.     

Nature and Thermal Behavior of Precipitated Calcium-Magnesium Phosphates

A group of crystalline and amorphous calcium-magnesium phosphates were prepared by exchange in solution of sodium orthophosphate and calcium and magnesium chlorides at pH 8-12. The behavior of the phosphates on heating to 1000°C was studied.     

State of Cu2+ ions in precipitated and thermally treated amorphous calcium-magnesium monophosphates doped with copper

Dehydration products of precipitated amorphous calcium-magnesium monophosphates (orthophosphates) with the atomic ratio Mg/(Mg + Ca) of 0.3 doped with copper were studied by the UV and IR Fourier spectroscopy. The substances retain the amorphous nature even on heating up to 550–600°C. Cations Cu²⁺ in them are in an octahedral surrounding of oxygen atoms and are linked with PO ₄ ^3? groups and, possiblly, with CO ₃ ^2? anions. The OH groups characteristic of hydroxyapatite are not found in the structure. Above 600°C the phosphates crystallize, therewith copper passes in the composition forming crystalline phases, retaining the octahedral surrounding of Cu²⁺ ions.