TY - JOUR

T1 - Synthesis and crystal structure of carbonate cancrinite Na8[AlSiO4]6CO3(H2O) 3.4, grown under low-temperature hydrothermal conditions

AU - Hackbarth, K.

AU - Gesing, Th M.

AU - Fechtelkord, M.

AU - Stief, F.

AU - Buhl, J. Ch

N1 - Funding Information: We thank Dr. W. Lutz (WITEGA GmbH, Berlin) for the water sorption measurements. This work was supported by Deutsche Forschungsgemeinschaft.

PY - 1999/9

Y1 - 1999/9

N2 - The synthesis of cancrinite in the system Na2O-SiO2-Al2O3-Na 2CO3-H2O was studied under low-temperature hydrothermal conditions in the 353K<T<473K interval. The aim was to reveal the suitable range for the crystallization of pure-phase carbonate cancrinite with the ideal composition Na8[AlSiO4]6CO3(H2O) 2 without cocrystallization of sodalite or intermediate disordered phases between cancrinite and sodalite. It was found that cancrinite formation reacts very sensitive on the temperature within the autoclaves whereas the concentration of reactants and the alkalinity of the hydrothermal solution have a much lower influence on the phase formation. Thus the temperature of crystallization of carbonate cancrinite without any by-products should not remain below 473K. At the lower reaction temperature of 353K the formation of a disordered intermediate phase between the cancrinite and the sodalite structure has been obtained in every case, independent of the template concentrations and the base. Some problems to detect this in a typical powder product mixture are discussed. Besides the 29Si and 27Al MAS NMR characterization of the products, the crystal structure refinement of pure carbonate cancrinite of ideal composition Na8[AlSiO4]6CO3(H2O) 3.4, has been carried out from X-ray powder data using the Rietveld method: P63, a=1271.3(1)pm, c=518.6(1)pm, RWP=0.073, RF=0.016 for 347 structure factors and 45 variable positional parameters.

AB - The synthesis of cancrinite in the system Na2O-SiO2-Al2O3-Na 2CO3-H2O was studied under low-temperature hydrothermal conditions in the 353K<T<473K interval. The aim was to reveal the suitable range for the crystallization of pure-phase carbonate cancrinite with the ideal composition Na8[AlSiO4]6CO3(H2O) 2 without cocrystallization of sodalite or intermediate disordered phases between cancrinite and sodalite. It was found that cancrinite formation reacts very sensitive on the temperature within the autoclaves whereas the concentration of reactants and the alkalinity of the hydrothermal solution have a much lower influence on the phase formation. Thus the temperature of crystallization of carbonate cancrinite without any by-products should not remain below 473K. At the lower reaction temperature of 353K the formation of a disordered intermediate phase between the cancrinite and the sodalite structure has been obtained in every case, independent of the template concentrations and the base. Some problems to detect this in a typical powder product mixture are discussed. Besides the 29Si and 27Al MAS NMR characterization of the products, the crystal structure refinement of pure carbonate cancrinite of ideal composition Na8[AlSiO4]6CO3(H2O) 3.4, has been carried out from X-ray powder data using the Rietveld method: P63, a=1271.3(1)pm, c=518.6(1)pm, RWP=0.073, RF=0.016 for 347 structure factors and 45 variable positional parameters.

KW - Carbonate-cancrinite

KW - Crystal structure

KW - Identification

KW - MAS NMR

KW - Synthesis

UR - http://www.scopus.com/inward/record.url?scp=0032681709&partnerID=8YFLogxK

U2 - 10.1016/S1387-1811(99)00046-3

DO - 10.1016/S1387-1811(99)00046-3

M3 - Article

AN - SCOPUS:0032681709

VL - 30

SP - 347

EP - 358

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

SN - 1387-1811

IS - 2-3

ER -