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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 10, Number 4
BKCSDE 10(4)
April 20, 1989 

Two Crystal structures of Fully Dehydrated Partially Magnesium Exchanged Zeolite A, Mg1.5Na9-A and Mg2.5Na7-A
Yang Kim*, Suk Hee Lee, Jong Yul Park, Un Sik Kim
Two Crystal structures of fully dehydrated partially magnesium exchanged zeolite A, stoichiometries of Mg2.5Na7-A (a = 12.251 (1) Å) and Mg1.5Na9-A (a = 12.214(1) Å) per unit cell, have been determined from the 3-dimensional X-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 21(1)℃. The structures of the dehydrated Mg2.5Na7-A and Mg1.5Na9-A were refined to yield the final error indices R1 = 0.042 and R2 = 0.049 with 318 reflections, and R1 = 0.034 and R2 = 0.032 with 252 reflections, respectively, for which I > 3σ(I). Both structures indicate that Mg2+ ions are coordinated by three framework oxygens and the angle substended at Mg2+ ions, O(3)-Mg(1)-O(3) is ca. 120°, close to the idealized trigonal planar value. Mg2+ ions preferentially occupy 6-ring sites and Na+ ions occupy 8-ring sites when total number of cations per unit cell is more than 8.
349 - 352
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