Scolecite, Part I: Refinement of high-order data, separation of internal and external vibrational amplitudes from displacement parameters

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

“…[1] is equivalent to the expanded form (8) of the ZFS Hamiltonians, whereas the operatorsT LM (11) belong to the category of the "normalized combinations of spherical tensor (NCST) operators" (8) introduced earlier in (13, 14); apart from the coefficient √ 2. Consequently the operatorsT LM are equivalent (to within the scaling factor for a given L) to the normalized Stevens (NS) operators of Gaite at al., e.g., (6,15); for details see (16) and the review (8).…”

“…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.…”

“…The rotational invariant for the ZFS tensor of rank L in Eq. [1] is defined (11) as the invariant sum…”

Infrared spectroscopic characterization of dehydration and accompanying phase transition behaviors in NAT-topology zeolites

“…Many dehydration studies for mesolite and scolecite, including ours (e.g., Adiwidjaja 1972;van Reeuwijk 1974;Ståhl and Thomasson 1994;Ståhl and Hanson 1994;Kolesov and Geiger 2006;Prasad et al 2006;Prasad and Prasad 2007;, indeed showed two-step dehydration behaviors, with the loss of mesolite Ow4 and scolecite Ow3 H 2 O molecules as the first step of dehydration. Unfortunately, hydrogen bond lengths determined from various diffraction results (e.g., Joswig et al 1984;Artioli et al 1986;Kvick et al 1985;Stuckenschmidt et al 1997;Kuntzinger et al 1998;Stuckenschmidt and Kirfel 2000) are quite variable, probably due to the difficulty in determining accurate proton positions for H 2 O molecules in a complex threedimensional structure. In addition, the Ca-Ow4 bonds in mesolite and the Ca-Ow3 bonds in scolecite showed a tendency to be slightly longer (by *0.03 Å ) than the other Ca-Ow distances found in mesolite (i.e., Ca-Ow2 and CaOw3) and scolecite (i.e., Ca-Ow1 and Ca-Ow2), which is also consistent with their dehydration behaviors.…”

Zeolites of the Natrolite-Thomsonite Series

“…Calcium substitution on all of the sodium sites (scolecite) leads to monoclinic distortion of the structure [27,28]. The nominal composition of scolecite contains three water molecules per formula unit.…”