Many researchers have suggested [1,6,15,16] that pure LDH phases can only be formed for stoichiometries in the range of 0.20 < x < 0.33, corresponding to M(II)/M(III) ratios in the range of 2–4. For x > 0.33, the presence of M(III)–O–M(III) linkages is unavoidable and this is energetically unfavourable due to the strong repulsion between the adjacent trivalent cations