Ab Initio Structure Determination of New Mixed Zirconium Hydroxide Nitrates ZrM(OH)2(NO3)3 (M=K, Rb) from X-Ray Powder Diffraction Data
✍ Scribed by P. Bénard-Rocherullé; D. Louër
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 292 KB
- Volume
- 149
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Two
new mixed zirconium hydroxide nitrates ZrM(OH) 2 (NO 3 ) 3 (M ؍ K, Rb) have been synthesized through a wet chemical process. The two crystal structures have been solved ab initio from powder di4raction data collected with conventional monochromatic X-rays. ZrK(OH) 2 (NO 3 ) 3 crystallizes with a monoclinic symmetry [a ؍ 16.569(3) A s , b ؍ 5.791(1) A s , c ؍ 9.813(2) A s , ؍ 90.17(2)3, P2 1 /n, Z ؍ 4) and ZrRb(OH) 2 (NO 3 ) 3 with an orthorhombic symmetry [a ؍ 10.126(3) A s , b ؍ 16.492(3) A s , c ؍ 5.855(2) A s , Pbcn, Z ؍ 4]. The heavy atoms have been located from an interpretation of Patterson functions. The coordinates of the remaining light atoms have been determined from successive three-dimensional Fourier maps. The 5nal Rietveld re5nement indicators were R F ؍ 0.042, R p ؍ 0.077 (M ؍ K) and R F ؍ 0.064, R p ؍ 0.115 (M ؍ Rb). Like the structures of
-Zr(OH) 2 (NO 3 ) 2 ' 1.65H 2 O and -Zr(OH) 2 (NO 3 ) 2 ' H 2 O, the structures of the mixed basic zirconium nitrates are built from edge-sharing ZrO 8 polyhedra to form in5nite neutral zigzag chains of chemical composition [Zr(OH) 4/ 2 (NO 3 ) 2 ] n . The main di4erence with respect to the hydrated phases is the nature of the cohesion in the structures based on ionic contacts involving intercalated K ؉ or Rb ؉ and NO ؊ 3 species in the mixed compounds and on a complex hydrogen-bonding network in the hydrated phases. The crystal chemistry of the zirconium hydroxide nitrates is discussed and three structure types are identi5ed.