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Single phase M₂Si (M = Mg, Ca, Sr) silicides were grown using Si substrates, by thermal treatment of the substrates in the vapors of the metallic sources, M, and the electronic structures and optical property of the silicides were investigated. The electronic band structures of the silicides were calculated using the first-principles total-energy calculation program in pseudopotential schemes with plane-wave basis functions. The calculated optical reflectance spectra were also deduced from the theoretical band structures, and roughly agreed with the experimental results except for the low reflectance intensity around 2 eV. This suggests that the energy band gap of the silicides roughly agree with the calculated values of 0.15, 0.31 and 0.35 eV for Mg₂Si, Ca₂Si and Sr₂Si, respectively, within the underestimation of the band gap by the density functional calculation. The optical property of the silicides is also discussed in relation to the morphological structures of the silicides.

In the present work, based on first-principles calculations, we show that it is possible to obtain a new high pressure polymorph of the CaSi₂ compound with a Laves structure. It corresponds to the MgCu₂-type (C15) which is one of the three most important Laves phases. We also show that the two other structures, MgNi₂- and MgZn₂-types are very competitive energetically and are possible candidates for finite temperature investigations.

A variety of nanostructure bundles and arrays based on semiconducting metal silicides have been synthesized using abundant and non-toxic starting materials. Three types of fabrication techniques of the nanostructure bundles or arrays, including direct growth, template synthesis using natural nanostructured materials and template synthesis using artificially fabricated nanostructured materials are demonstrated. CrSi₂ nanowire bundles were directly grown by the exposure of Si substrates to CrCl₂ vapor at atmospheric pressure. A hexagonal MoSi₂ nanosheet, Mg₂Si/MgO composite nanowire and Mg₂Si nanowire bundles and MnSi_1.7 nanowire array were synthesized using a MoS₂ layered material, a SiO_x nanofiber bundle, a Si nanowire array, and a Si nanowire array as the templates, respectively. Additionally, the fabrication phenomenon and structural properties of the nanostructured semiconducting metal silicides were investigated. These reactions provided the low-cost and controllable synthetic techniques to synthesize large scale and one-dimensional semiconducting metal silicides for thermoelectric applications.