Comments on quasicrystals and their potential use as catalysts

Ames Laboratory and Department of Chemistry, Iowa State University, Ames, IA 50011, USA
Journal of Molecular Catalysis A Chemical (Impact Factor: 3.62). 05/1998; 131(1-3):301-306. DOI: 10.1016/S1381-1169(97)00272-0


Recent findings suggest that quasicrystalline materials may make better catalysts than their crystalline counterparts. On the other hand, detailed surface science studies suggest that the surfaces of Al-based quasicrystals behave as if they are chemically similar to pure Al. In this paper, we discuss these results along with the unique thermodynamic and electronic properties of quasicrystals which could affect their catalytic nature.

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    • "Quasicrystals (QCs) are solids with rotational symmetry and aperiodic or ''quasiperiodic'' translational symmetry [1]. This relatively new class of solids was first identified in 1984 [2] and since then, considerable research has been conducted in the field leading to reports of quasicrystalline phases in over 100 systems with several metals serving as the primary constituent, i.e., Al [3] [4], Cu [5] [6], Ga [7], Mg [8] [9], Ni [10], Ta [11] [12], Ti [13] [14], Zn [15] [16] and Zr [17] [18]. In the last decade, there have been significant efforts to identify commercial applications that might benefit from the QC phases [8] [19] [4] especially in those alloys where these phases appear to enhance the mechanical properties or render the material with distinct functional properties [9]. "
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    ABSTRACT: Abstract Rapidly solidified Al-Mn-Ce alloys have been reported to exhibit desirable properties due to the uniform distribution of quasicrystalline (QC) particles in an Al matrix. In this study, several ternary alloy compositions that encompassed the alloys reported in the previous reports, namely Al-6Mn-2Ce, Al-6Mn-4Ce, Al-8Mn-4Ce, Al-12Mn-2Ce and Al-10Mn-5Ce, were prepared by melt spinning and their microstructures were characterized by electron microscopy and X-ray diffraction. The results are in direct contrast with the previous reports available in the literature in that the formation of QCs was only observed in the Al-12Mn-2Ce alloy; in the others, the dispersed phase was not the QC; rather, the structural and compositional information presented in this paper together with data recently published in the literature enabled a reinterpretation of the effect of Ce on rapidly solidified Al-Mn alloys. The main conclusion is that Ce favors the formation of a ternary metastable phase with approximate stoichiometry Al20Mn2Ce. This phase forms in a wide portion of the Al-rich region of the ternary phase diagram and can even coexist with the QC phase in alloys containing low amounts of Ce; in this case, the QC contains no detectable Ce by TEM/EDS, consistent with the conclusion that Ce does not favor QC formation in contrast to the previous reports.
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    ABSTRACT: The reaction between i-Al-Cu-Fe alloy powder and nitrogen oxide (NO) at high temperature was studied. It was found that the powder has a high capacity for the decomposition of NO at high temperature, and that the quasicrystal phase of a higher purity shows a higher activity.
    Full-text · Article · Jun 2001 · Journal of Materials Science Letters
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