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KMID : 0385520050180040278
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Analytical Science & Technology
2005 Volume.18 No. 4 p.278 ~ p.286
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Crystallographic analysis of dehydrated fully Tl+ - exchanged zeolite Y
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Lim WT
Kwon JH/Choi SY/Kim YH/Heo NH
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Abstract
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The crystal structure of Tl_(71)-Y(Tl_(71)Si₁₂₁Al_(71)O_(384)), α=24.706(3) Å, dehydrated at 653 K and 8×10^(-6) torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3m at 294(1)K. The structure was refined using all intensities to the final error indices (using only the 302 reflection for which F。>4σ(F。)) R₁=0.0602 (based on F) and Rw=0.1744 (based on F₂). The 71 Tl+ ions per unit cell are found at four crystallographically distinct positions. Site I’ position in the sodalite cavity opposite D6Rs are each occupied by eighteen Tl+ ions per unit cell; these Tl+ ions are recessed ca. 1.45 Å into the sodalite cavity from their O(3) plane (Tl-O=2.701(15), 3.163(16) Å and O-Tl-O=92.1(4)˚). The 23 T1+ ions fill site Ⅱ in the supercage; these T1+ ions are recessed ca. 1.58 Å into the supercage from their O(2) plane (Tl-O= 2.850(16), 3.156(16) Å and O-T1-O = 85.1(5)˚). The 19 Tl+ ions lie at site Ⅲ’ in the supercage near a triple 4-ring (Tl-O = 3.10(7), 3.39(5) Å and O-Tl-O = 47.8(9), 95.3(18)˚) and the remaining Ⅱ ions occupy another site Ⅲ’ near a triple 4-ring in the supercage (Tl-O = 2.81(4), 2.71(4) Å and O-Tl-O = 57.3(8)˚).
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