Formation of Si-based Nanosheet Bundles and Morphological Modication of CaSi₂ Crystals by Thermal Treatment Using Chloride Compounds

Abstract

Si-based nanosheet bundles were formed by Ca-atom extraction from CaSi₂ crystals by thermal treatment using FeCl₂, FeCl₃, NH₄Cl, and MgCl₂. The morphological property of the Si-based nanosheet bundles was examined. Though the Si-based nanosheets were formed under the stated thermal treatment conditions using FeCl₃, the formation of iron-oxide phases was accelerated at higher temperatures and longer duration times for the highest thermal treatment temperatures using FeCl₂. Thinner and thicker nanosheets were obtained using NH₄Cl and MgCl₂, respectively. The morphological properties of the Si-based nanosheet bundles were compared to each other and their formation mechanism was discussed in terms of the thermal instability of the chlorides, their vapor pressure and thermal treatment temperature profiles. [DOI: 10.1380/ejssnt.2018.218]