Impact of temperature dependent octahedra distortions on magnetic properties of Co-containing double layered hydroxides

Distortions of hydroxide octahedral complexes in the (ConAlIII)-Al-II layered double hydroxides (LDHs) (n = Co-II/Al-III = 2 and 3) were studied as a function of the ratio of divalent-to-trivalent cations and temperature. A method for calculation the magnetic susceptibility of polycrystalline samples taking into account the statistical distribution of divalent and trivalent cations, and their effect on the distortions of the original structure is proposed. It is shown that the presence of a local maximum on the magnetic susceptibility curve of ConAl LDHs compounds near T similar to 160 K is due to freezing of the lattice parameters and, as a consequence, freezing of the tilting fluctuations of the O-H bonds.