IV/r = 3041•84, orthorhornbic, Fdd2, a = 18•272(6), b=18•613(6), c=6•593 (2) A, v= 2242 (2) A3, Z = 8, D< = 2•25 g cm=, Ge(331)-monochrornatized neutrons, À = O• 8263 (L) A, !1= 0•404 crn", 20 K, R(F2) = 0•044 (1976 refìections), Thc tetrahedral sites have complete Al2Si] order. Although the Si-O and Al-O distances correlate inversely with the Si-O-AI angle as far other ordered fìbrous zeolites, there are differences which may relate to the ionic potenti al of the extraframework cations. This fourth paper on the bonding ofwater molecules in fibrous zeolites [edingtonite (Kvick & Smith, 1983); scolecite (Smith, Pluth, Artioli & Ross, 1984); thomsonite (Pluth, Smith & Kvick, 1984)j provides precise coordìnates for natrolite at 20 K. Positions of framework atoms, sodium atoms and water atorns at room temperature were determìned with lower precision by Taylor, Meek & Jackson (1933), Meier (1960) and Torrie, Brown & Petch (1964). Most natrolìte crystals are almost pure Na2AI2Sì30lO.2Hp with essentially complete A12Si3 ordering (Alberti, Pongiluppi & Vezzalini, 1982), but some have minor Al, Si disorder (Pabst, 1971; Alberti & Vezzalini, 1981; Hesse, 1983). The highest syrnmetry of the ToO IO tetrahedral framework of natroiiteis 141/a2/m2/d (Smith, 1983), but the rotation of the 4-1 chains in the 0246 arrangement (Alberti & Gottardi, 1975) and the topochernistry of the Al2Si3 type of ordering result in space group Fdd2. Heating above room temperature causes loss of water, rotation of the 4-1 chains, and movement of the sodium atorn (Peacor, 1973; Alberti & Vezzalini, 1983).

Neutron diffraction study of natrolite, Na2Al2Si3O10×2H2O, at 20 K

ARTIOLI, GILBERTO;
1984

Abstract

IV/r = 3041•84, orthorhornbic, Fdd2, a = 18•272(6), b=18•613(6), c=6•593 (2) A, v= 2242 (2) A3, Z = 8, D< = 2•25 g cm=, Ge(331)-monochrornatized neutrons, À = O• 8263 (L) A, !1= 0•404 crn", 20 K, R(F2) = 0•044 (1976 refìections), Thc tetrahedral sites have complete Al2Si] order. Although the Si-O and Al-O distances correlate inversely with the Si-O-AI angle as far other ordered fìbrous zeolites, there are differences which may relate to the ionic potenti al of the extraframework cations. This fourth paper on the bonding ofwater molecules in fibrous zeolites [edingtonite (Kvick & Smith, 1983); scolecite (Smith, Pluth, Artioli & Ross, 1984); thomsonite (Pluth, Smith & Kvick, 1984)j provides precise coordìnates for natrolite at 20 K. Positions of framework atoms, sodium atoms and water atorns at room temperature were determìned with lower precision by Taylor, Meek & Jackson (1933), Meier (1960) and Torrie, Brown & Petch (1964). Most natrolìte crystals are almost pure Na2AI2Sì30lO.2Hp with essentially complete A12Si3 ordering (Alberti, Pongiluppi & Vezzalini, 1982), but some have minor Al, Si disorder (Pabst, 1971; Alberti & Vezzalini, 1981; Hesse, 1983). The highest syrnmetry of the ToO IO tetrahedral framework of natroiiteis 141/a2/m2/d (Smith, 1983), but the rotation of the 4-1 chains in the 0246 arrangement (Alberti & Gottardi, 1975) and the topochernistry of the Al2Si3 type of ordering result in space group Fdd2. Heating above room temperature causes loss of water, rotation of the 4-1 chains, and movement of the sodium atorn (Peacor, 1973; Alberti & Vezzalini, 1983).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2496736
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