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キーワード:
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要旨:
An amorphous phase at composition Zn2Si5(:H,OH) was prepared by oxidation of the precursor phase Li2ZnSi at 80 degrees C in the ionic liquid of n-dodecyltrimethylammonium chloride (DTAC) and AlCl3 in 1:1 molar ratio, followed by removal of elemental zinc by dilute aqueous HCl. The product was structurally amorphous according to HRTEM, XRPD, and Raman spectroscopy. Zn2Si5(:H,OH) forms layers embedded in a matrix of a silica by-product. On annealing at 150 degrees C, amorphous Zn2Si5(:H,OH) decomposed into crystalline Zn and -Si. The decomposition comes along with the release of H-2 revealed by TG-MS studies. IR and solid-state NMR spectroscopy revealed that the Zn2Si5 bulk is terminated by Si-OH and Si-H groups. The absence of Knight shift in the Si-29 NMR signal assigned to Zn2Si5(:H,OH) suggests semiconducting behavior.
