Thermal expansion of boehmite: An anomaly near 560 K due to non-stoichiometric water

Abstract The thermal expansion of boehmite, A1OOH, has been investigated between 78 and 650 K. The results show a contraction of all lattice parameters around 560 K. A differential scanning calorimetric study reveals that two successive thermal effects exist around this temperature. The first effect is an exotherm related to a structural reorganization characterized by a contraction of one lattice parameter: c . The second effect is an endotherm, which is associated with a loss of non-stoichiometric water, characterized by a contraction perpendicular to the layers, along b axis.