RESULTS OF THE CRYSTALLIZATION OF ZEOLITE MOLECULAR-SIEVES UNDER MICROGRAVITY CONDITIONS DURING THE EURECA-1 MISSION

The results of the physical and chemical characterisation of the crystalline zeolite phase obtained in the solution growth facility during the EURECA-1 mission are presented. Comparisons of crystal size and morphology of materials obtained in parallel ground experiments and typical optimised gel syntheses show significant, though not marked differences. Two crystalline phases were obtained, the zeolites offretite and sodalite, in both microgravity and flight experiments. Offretite crystals from the ground experiments exhibited near spherical morphology of dimensions less than 0.5 mu M. Equivalent crystals obtained in the flight experiments had developed into thick fed-like crystals of dimensions approximately 2 x 0.6 mu m. Both these results can be contrasted with the typical gel syntheses under the same conditions in which a pure offretite phase is obtained with spherical crystals under 0.5 mu m in dimensions.