Electron crystallography of zeolites. 3. Calcined MCM-22 and MCM-49, a case of subtle differences
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Douglas L. Dorset
Abstract
Single crystal electron diffraction intensity data, analyzed by direct methods for determining crystallographic phases, have been employed to seek differences between the crystal structures of calcined MCM-22 and MCM-49. A direct comparison of hk0 intensity data indicates such a difference and this is justified further when the respective structural models are refined. The MCM-22 data agree well with the ITQ-1 Si-framework model, but without adding the extraneous interstitial atoms imposed in an earlier powder X-ray diffraction determination. The T-sites in MCM-49 are placed similarly to the ones in MCM-22 but Fourier refinement indicates the presence of an oxygen site not seen for MCM-22. Also one of the oxygen positions found in MCM-22 is not observed in the MCM-49 potential maps.
© 2003 Oldenbourg Wissenschaftsverlag GmbH
Artikel in diesem Heft
- Theoretical explanation of the octahedral distortion in FeF2 and MgF2
- Rational approximants to 5, 8 and 7-fold two-dimensional tilings
- The cubic limiting complexes of the tetragonal lattice complexes
- The crystal structures of the potassium hydrogen monofluorophosphates, KHPO3F and K3[H(PO3F)2], and the α modification of RbHPO3F
- Electron crystallography of zeolites. 3. Calcined MCM-22 and MCM-49, a case of subtle differences
- Crystal structures, order-disorder transition and twinning of the Jahn-Teller system (NO)2VCl6
- Structural and physical properties of bis(guanidinium) X bis(nitrilotriacetate) hydrate, (C[NH2]3)2X(N[CH2COO]3)2·H2O (X = Zr, Sn, Hf) and bis(methylammonium) X bis(nitrilotriacetate dihydrate, (CH3NH3)2X(N[CH2COO]3)2·2 H2O (X = Sn, Zr)
- Dichloro[(E)-2-chloro-1-vinyl-cyclohexanol](4-methoxy phenyl)Te(IV). A case of conformational polymorphism
- Plane groups – from basic to advanced crystallographic concepts
- Books Received
Artikel in diesem Heft
- Theoretical explanation of the octahedral distortion in FeF2 and MgF2
- Rational approximants to 5, 8 and 7-fold two-dimensional tilings
- The cubic limiting complexes of the tetragonal lattice complexes
- The crystal structures of the potassium hydrogen monofluorophosphates, KHPO3F and K3[H(PO3F)2], and the α modification of RbHPO3F
- Electron crystallography of zeolites. 3. Calcined MCM-22 and MCM-49, a case of subtle differences
- Crystal structures, order-disorder transition and twinning of the Jahn-Teller system (NO)2VCl6
- Structural and physical properties of bis(guanidinium) X bis(nitrilotriacetate) hydrate, (C[NH2]3)2X(N[CH2COO]3)2·H2O (X = Zr, Sn, Hf) and bis(methylammonium) X bis(nitrilotriacetate dihydrate, (CH3NH3)2X(N[CH2COO]3)2·2 H2O (X = Sn, Zr)
- Dichloro[(E)-2-chloro-1-vinyl-cyclohexanol](4-methoxy phenyl)Te(IV). A case of conformational polymorphism
- Plane groups – from basic to advanced crystallographic concepts
- Books Received
