AlPO4 solid solutions containing Ca and Zn phosphates

Abstract Portions of an Al 2 O 3 ·3H 2 OH 3 PO 4 CaO compositional triangle were examined at 300°C for a solid solution of Ca (presumably in the form of Ca(H 2 PO 4 ) 2 ) in the Cristobalite AlPO 4 crystal structure. X-ray diffraction patterns of the various compositions showed the existence of such a solid solution including a lattice parameter change. The limit of the solid solution was approximated at composition 2CaO, Al 2 O 3 ·3H 2 O, 6H 3 PO 4 . This solid solution, however, proved to be unstable at 800°C, but was stabilized by the addition of 1 4 mole ZnO at the limit composition. Three points in an Al 2 O 3 ·3H 2 OH 3 PO 4 ZnO compositional triangle were also examined and evidence of solid solution found including a lattice parameter change.