The formation of ZrP for the lowest H2PP content in the mother solution did not allow the exact composition of the mixed phase having an interlayer distance of 11.0 Å
to be known; however, since the interlayer distance of the powder samples increases with increasing PP content, it is reasonable to suppose that the x value of the solid, obtained for an H2PP molar fraction of 0.05 in the mother solution, is lower than that of the solid obtained for an H2PP molar fraction of 0.125, that is x < 0.43