Anisotropic compression of a synthetic potassium aluminogermanate zeolite with gismondine topology

作者：Jang Young Nam; Kao Chi Chang; Vogt Thomas; Lee Yongjae^*

来源：Journal of Solid State Chemistry, 2010, 183(10): 2305-2308.

DOI：10.1016/j.jssc.2010.07.041

• Zeolite
• Gismondine
• Pressure
• Compressibility

Compression behaviour of a potassium aluminogermanate with a gismondine framework topology (K-AlGe-GIS) was studied using in-situ high-pressure synchrotron X-ray powder diffraction. In contrast to the potassium gallosilicate analogue (K-GaSi-GIS), no elastic anomaly due to pressure-induced hydration and/or cation relocation was observed in K-AlGe-GIS. The Birch-Murnaghan fit to the pressure-volume data results in a bulk modulus of B(0)=31(1) GPa. The derived linear-axial compressibilities (i.e., beta(a)=0.0065(5) GPa(-1), beta(b)=0.0196(4) GPa(-1), beta(c)=0.0081(7) GPa(-1)) indicate that the b-axis, normal to the 8-ring channels, is about three times more compressible than the a and c axes, parallel to the elliptical 8-ring channels. As a consequence a gradual flattening of the so-called 'double crankshaft' structural building units of the gismondine framework is observed. In K-AlGe-GIS, this flattening occurs almost linear with pressure, whereas it is nonlinear in the GaSi-analogue due to structural changes of the water-cation assembly under hydrostatic pressures.

• 出版日期2010-10