Synthesis of spherical aggregates of leaf-like YPO4 particles via hydrolysis of tri-n-butylphosphate

Spherical aggregates of leaf-like YPO₄ particles have been prepared by the reactions of tri-n-butylphosphate [PO(OC₄H ₉)₃, TBP] with the acidic Y(NO₃)₃ aqueous solution in an autoclave at 180°. The products of the reactions for 1, 3 and 6 h consisted of an intermediate exhibiting an intense X-ray diffraction line at d μ 1.28 nm, while those of reactions for 1248 h were pure YPO4. The products of the reactions for 8 and 8.5 h were mixtures of the intermediate and YPO₄. YPO₄ formation thus seems to proceed via the formation of the intermediate. Since the intermediate seems to be Y[PO₂(OC₄H₉)₂]₃, it is likely that TBP was hydrolyzed to form PO₂(OC₄H ₉)^2- ions, which then reacted with Y³⁺ ions to form the solid intermediate, Y[PO₂(OC₄H₉) ₂]₃. Scanning electron microscopy (SEM) revealed the corresponding morphological change from the belt-like products to spherical aggregates of leaflike particles, indicating that the solid intermediate Y[PO₂(OC₄H₉)₂]₃ was hydrolyzed to form leaf-like YPO₄ particles.