Optical Investigations of Intergrowth Effects in the Zeolite Catalysts ZSM-5 and ZSM-8

Weidenthaler, Claudia; Fischer, R. X.; Shannon, R. D.; Medenbach, Olaf

doi:10.1021/j100099a036

Cited by 80 publications

(80 citation statements)

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“…Excellent contrast can be also obtained in the present case in an optical microscopic image under crossed polarizers ( Figure 5 c) as described previously. [24] The pattern is indicative of 908 intergrowths characteristic for large ZSM-5 crystals (Figure 2 d). [9,11,14,25] By comparing the models depicted in Figure 2 one can notice a striking similarity between their building blocks.…”

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confidence: 96%

“…[5] For example, the intergrowth structure of ZSM-5 crystals elucidated from electron diffraction, X-ray diffraction, and optical microscopy results has been discussed over the past 20 years. [11][12][13][14] Recently, Lehmann et al visualized subunits of AlPO 4 -5 crystals by probing intracrystalline concentrations of absorbed methanol by interference microscopy. [15] The hydrothermal synthesis of zeolites calls for structuredirecting agents, such as alkyl amines, to ensure their longrange highly ordered porous structure.…”

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confidence: 99%

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Intergrowth Structure of Zeolite Crystals as Determined by Optical and Fluorescence Microscopy of the Template‐Removal Process

et al. 2007

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confidence: 96%

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confidence: 99%

Intergrowth Structure of Zeolite Crystals as Determined by Optical and Fluorescence Microscopy of the Template‐Removal Process

et al. 2007

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“…[18][19][20][21] These are formed by a rapid growth along the crystallographic c axis during the early stages of the synthesis. As shown in Figure 1 b the crystallographic axes of segments 2 and 6 coincide with each other, and with those of segments 1 and 4, but not with those of 3 and 5.…”

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confidence: 99%

Exploring Crystal Morphology of Nanoporous Hosts from Time‐Dependent Guest Profiles

Tzoulaki¹,

Heinke²,

Schmidt³

et al. 2008

Angew Chem Int Ed

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“…Samples were oriented with a four-circle x-ray diffractometer before the Brillouin experiments. Although twinning is commonly found in silicalite crystals, [28][29][30] no evidence of twins was indicated by the x-ray in polished crystals used in our measurements.…”

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confidence: 52%

Negative Poisson’s ratios in siliceous zeolite MFI-silicalite

Sanchez-Valle

Lethbridge

Sinogeikin

et al. 2008

The Journal of Chemical Physics

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Brillouin scattering measurements of the single-crystal elastic properties of the as-made zeolite silicalite ͉͑C 3 H 7 ͒ 4 NF͉ 4 ͓Si 96 O 192 ͔-MFI provides the first experimental evidence for on-axis negative Poisson's ratios ͑auxeticity͒ in a synthetic zeolite structure. MFI laterally contracts when compressed and laterally expands when stretched along x 1 and x 2 directions in the ͑001͒ plane ͑ 12 = −0.061, 21 = −0.051͒. The aggregate Poisson's ratio of MFI, although positive, has an anomalously low value = 0.175͑3͒ compared to other silicate materials. These results suggest that the template-free MFI-silicalite ͓Si 96 O 192 ͔ might have potential applications as tunable sieve where molecular discriminating characteristics are adjusted by application of stress along specific axes. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2912061͔ Materials with a negative Poisson's ratio known as auxetics are solids that exhibit the unusual property of laterally expanding under uniaxial tension and laterally shrinking under uniaxial compression. 1,2 Far from being a mere scientific curiosity, these materials have important applications in various technologies and are of interest to a range of scientific communities, from chemistry to material engineering. Their unusual mechanical properties, indeed, give rise to a long list of measured and predicted technological enhancements, such as improved plane-strain fracture toughness, and increased indentation resistance, 2 improved honeycomb dielectric properties, 3 self-adaptative vibrational damping properties, 4 increased shear modulus, improved sound and shock absorption, and the ability to form dome-shaped surfaces. 5 The identification of auxetic behavior on an atomic level has also opened up the possibility of molecular-scale amplifiers and other nanoscale devices. 6 Given the widespread potential applications of these materials, experimental and theoretical investigations have focused for the past few years into the identification and refinement of new auxetic materials and understanding the physical basis of this unusual property. Negative Poisson's ratios have been experimentally identified in a number of organic and inorganic materials, both in crystalline and amorphous forms, including polymers, foams, elemental cubic metals and alloys, and the silica polymorph ␣-cristobalite. 5,[7][8][9][10][11][12] The latter is, in fact, the only known crystalline silicate possessing an aggregate negative Poisson's ratio ͑ = −0.16͒, which has been interpreted as arising from the concurrent rotation of the SiO 4 -tetrahedral building units 13,14 under an applied stress. The search for auxetic materials has targeted other related low-density openframework SiO 2 -based structures, and recent simulations performed by Grima et al. have predicted negative Poisson's ratios in a number of idealized siliceous zeolites. 15 However, the lack of accurate experimental data on the elastic properties of zeolites has precluded confirmation of these predictions for many years.To address th...

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Optical Investigations of Intergrowth Effects in the Zeolite Catalysts ZSM-5 and ZSM-8

Cited by 80 publications

References 4 publications

Intergrowth Structure of Zeolite Crystals as Determined by Optical and Fluorescence Microscopy of the Template‐Removal Process

Intergrowth Structure of Zeolite Crystals as Determined by Optical and Fluorescence Microscopy of the Template‐Removal Process

Exploring Crystal Morphology of Nanoporous Hosts from Time‐Dependent Guest Profiles

Negative Poisson’s ratios in siliceous zeolite MFI-silicalite

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