The thermal behaviour of liottite

Thermal behaviour of liottite, the ABABAC six-layer member of the cancrinite-sodalite supergroup, has been investigated in situ real-time using laboratory parallel-beam X-ray powder diffraction data. Thermal expansion has been analysed from 323 to 1,223 K with temperature steps of 25 K. Dependence of the hexagonal cell parameters from temperature indicates a different behaviour with respect to afghanite, an ABABACAC eight-layer member of the supergroup. Three different regimes were observed, the last coincident with the starting of the conversion of liottite to hauyne (prevailing) and leucite-HT (minor). A smaller thermal expansion as compared to afghanite was observed. Isothermal annealing at 1,173 K led to a more extended conversion to hauyne, an a-parameter contraction, and a c-parameter expansion with respect to the starting RT cell parameters.