Elastic behavior and phase stability of pollucite, a potential host for nuclear waste

Zeolites at high pressure: A review

“…The relaxation mechanisms lead to a strong distortion of the four-and six-membered rings, along with a rearrangement of the extra-framework species. Gatta et al (2008aGatta et al ( , 2009a investigated the highpressure behaviour of leucite and pollucite, respectively and Ori et al (2008b) described that of wairakite. These experiments showed that P-induced high-symmetry to low-symmetry phase transitions occur in zeolites of ANA-framework type: leucite has a first-order phase transition from tetragonal to triclinic symmetry (I4 1 /a ?…”

“…For analcime, leucite, pollucite and wairakite, the high-P polymorphs are more compressible than the low-P ones (Table 1). Gatta et al (2009a) suggested that there is not a simple relation between the ionic radius of the extra-framework cation and transition pressure in the ANA-framework zeolites; this is because the configuration of the extra-framework species is significantly different [i.e. NaO 4 (H 2 O) 2 -polyhedron in low-P analcime; KO 6 in low-P leucite, with the K-sites located at the same positions as the O atoms of the H 2 O molecules in analcime; CsO 12 -and NaO 4 (H 2 O) 2 -polyhedron in low-P pollucite; CaO 4 (H 2 O) 2 -polyhedron in low-P wairakite, with a configuration similar to that of analcime].…”

Thermal transformation of Cs-clinoptilolite to CsAlSi5O12

“…The cesium aluminosilicate CsAlSi 5 O 12 (CAS-framework type) [1] is one of the crystalline phases proposed as potential hosts for radioactive cesium [2e5], along with pollucite [6,7] and ABW [8,9]. This material has refractory properties [2], ensure the immobility of cesium at high temperature and pressure [5,10], shows thermoelastic stability and preserve its crystallinity at least up to 8.5 GPa and 1000 C [5].…”

On the high-pressure behavior of gobbinsite, the natural counterpart of the synthetic zeolite Na–P2

“…The increase of compressibility at high-P was already observed in other microporous materials which experience a P-induced displacive phase-transition [e.g. [47][48][49][50]]. A comparison with the elastic behavior of the GIS framework-type materials shows that gobbinsite is significantly more compressible than gismondine [28,29] (8) 3.728 (7) 3.684 (9) 3.70 (1) 3.621 (8) 3.64(1) O4-O5(Å) 3.79 (1) 3.77 (1) 3.78 (1) 3.83 (2) 3.91 (2) 3.93 (2) 3.83 (2) 4 mR [0 0 1] O1-O1(Å) 3.872 (7) 3.912 (9) 3.899 (7) 3.94 (1) 3.99 (1) 4.02 (1) 4.00(1) O4-O5(Å) 3.44 (1) 3.42 (2) 3.43 (1) 3.42 (2) 3.32 (2) 3.32 (2) 3.34 (3) (K V0 = 63.8(2) GPa in silicon oil) and less compressible than K-(Al,Ge)-GIS synthetic analogue (K V0 = 31(1) GPa) [34] and K-(Ga,Si)-GIS (K V0 = 69(1) GPa at P < 1 GPa, 41(2) GPa at P > 1 GPa) [33].…”