Year: 2025
Type: article
Abstract: This work is devoted to the study of phase equilibria in the BiPO4–YPO4–(nH2O) system under mild conditions. It was shown that using the precipitation method leads to crystallization of the samples into the rhabdophane phase YPO4 · nH2O and the ximengite phase BiPO4. Hydrothermal treatment of the samples at 160◦C results in the gradual transformation of hexagonal yttrium phosphate with a rhabdophane-type structure into tetragonal xenotime YPO4, and hexagonal bismuth phosphate with a ximengite-type structure into monoclinic bismuth phosphate (space group P 21/n). The transformation into the stable phases of xenotime and monoclinic bismuth phosphate is almost complete after 28 days of isothermal holding under hydrothermal conditions at 160◦C. Moreover, the lower the content of the second component in samples containing both Bi and Y, the faster the structural transformation into the stable phase proceeds. A solid solution based on monoclinic bismuth phosphate with the composition Bi0.94Y0.06PO4 is formed in the system. Before disappearing, the rhabdophane-type phase represents a solid solution with the composition Y0.8Bi0.2PO4 · nH2O. The crystallite sizes of all phases increase with an increase in the bismuth content in the system.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
Funder: Russian Science Foundation
OpenAlex ID: W4414023846