Physicochemical Properties of Nanosized Powders of the LaPO 4 –DyPO 4 –H 2 O System

Nanosized La1–xDyxPO4 · nH2O powders are synthesized by the sol-gel method using direct and reverse precipitation. The formation of a continuous series of hexagonal solid solutions based on LaPO4 · nH2O is confirmed by the XRD and DSC/TG methods. A continuous series of monoclinic solid solutions based on LaPO4 is formed at temperatures higher than 600°C. A reflex corresponding to a tetragonal form of DyPO4 is formed during the calcination of DyPO4 powder at 850°C. Two types of solid solutions are observed at temperatures of 1000–1200°C, namely, monoclinic solutions based on LaPO4 (to x ≈ 0.7) and tetragonal solutions based on DyPO4 (0.90 ≤ x ≤ 1.0). The results are compared depending on the methods of nanopowder synthesis.