Abstract: The colloidization (exfoliation) and hydrolysis of layered zirconium phosphate (α-ZrP-R), tin phosphate (α-SnP-R) and titanium phosphate (α-Tip-R) were investigated systematically.When the phosphate sheets exfoliate, HPO₄^2- and M⁴⁺ (M=Zr, Sn, Ti)leave the sheet surface and enter tl1e solution through hydrolysis.The hydrolysis of HPO₄^2-takes place before the loss of M⁴⁺, and as the hydrolysis extent of HPO₄^2- exceeds 40%, the layered structure of the phosphates will be destroyed.The colloidization and hydrolysls de-gree of the three phosphates in the same amine solutlon differ from each other.The sheets of α-TiP-Rhydrolyze readily and exfoliate wlth difficulty.In most cases the ex foliation of α-TiP-Roccurs only around the boundary of its sheets, and the complete exfoliation is hardly observed.The sheets of α-SnP-Rare more stable than those of α-TiP-R.They hydrolyze less readily and exfoliate more easily.The sheets of α-ZrP-Rare most stable toward hydrolysis and exfoliate easily in amine solution.For each kind of layered phosphates the adoption of an appropriate amine and suitable experirnental conditions are necessary to control the hydroly-sis and exfoliation of the phosphate sheets during preparation of various types of pillared phosphates or multifunctional films.

Key words: Layered phosphates, Colloidization, Stability