Structural transformations in natrolite and edingtonite

Effect of high-pressures on the electrical resistivity of natural zeolites from Deccan Trap, Maharashtra, India

“…Alberti and Vezzalini (1983) have studied single-crystal XRD of natrolite at hightemperatures and showed that natrolite transforms to a-metanatrolite near 160 8C. Further heating to 510 8C results in inverse transformation to h-metanatrolite (Belitsky et al, 1992). In metanatrolite, Na atoms occupy positions near those occupied by H 2 O in natrolite.…”

“…The phase stability, the phase changes and the dehydration of zeolites during heating at ambient pressure has been the subject of numerous experimental studies (Gottadi and Galli, 1985). However, there are only very few studies on the effect of pressure at room temperature on the stability of zeolites (Belitsky et al, 1992;Gillet et al, 1996;Parthasarathy and Gowd, 2000;Ballone et al, 2002;Arletti et al, 2003). Earlier high-pressure studies on natural zeolites based on visual observation, Raman spectroscopic and XRD suggested that natrolite group zeolites should undergo at least three pressure-induced phase transitions, while they are compressed in penetrating liquids up to 5 GPa.…”

Low-Symmetry Spin Hamiltonian and Crystal Field Tensors Analysis: Fe3+ in Natrolite

“…Ordered Na + ions and H 2 O molecules fill the voids of the framework. By the use of a wide range of different methods including Raman spectroscopy and NMR in (2) it was found that the change in chemical composition of the nonframework ions and/or water content is followed by orientational changes (tilting and rotating) of the framework tetrahedra. The flexibility of the natrolite framework also allows partial disorder in (Al, Si) distribution (3).…”

“…Natrolite, Na 2 (1), is one of the fibrous zeolites with the framework constructed from the chains of corner-sharing Al and Si oxygen tetrahedra. The main structural unit is Al 2 Si 3 O 10 consisting of five tetrahedra, of which four are bound into the ring and the fifth, the SiO 4 tetrahedron, links the rings to form the chain extended along the c-axis (Fig.…”

Templating multiple length scales by combining phase separation, self-assembly and photopatterning in porous films

“…Porous materials are commonly encountered in nature ranging from inorganic minerals [1] to hierarchically biodirected materials [2] such as bone. Industrially porous materials are equally ubiquitous in applications such as catalysis [3], separations [4], sensors [5], medical diagnostics [6], and dielectric materials in microelectronics [7].…”