Synthesis, structural and photoluminescence properties of Mg₂Si/Si nanocomposites consisting of Si nanosheet bundles and Mg₂Si deposits

Abstract

Mg2Si/Si nanocomposites, consisting of Si nanosheet bundles and Mg2Si deposits formed on the Si nanosheet bundles, were formed by the thermal annealing of CaSi2 powders in MgCl2 vapor. Mg atoms are deposited on the Si nanosheet bundles, and the surface of the nanosheets were partially transformed into the Mg2Si phase during the thermal treatment. The Mg2Si/Si composites were also synthesized on Si(111) substrates. The structural and photoluminescence (PL) properties of the composites were characterized. The Mg2Si deposits were inhomogeneously distributed on the Si nanosheets. Furthermore, the Si-based nanosheets consisted of disordered thinner Si layers, and a disordered superlattice-like layered structural model is shown. The PL emissions in the visible region were clearly observed, and the temperature and the excitation intensity dependences of the emissions were characterized. It was found that the structural modification of the Si nanosheet bundles to form the composites with Mg2Si deposits affected the emission property of the Si nanosheets. The luminescence mechanism of the composite was discussed.

Fine structural and photoluminescence properties of Mg2Si nanosheet bundles rooted on Si substrates

“…It should be noted that in a previous study, a new emission peak at approximately 1.9-2.0 eV appeared for a Mg 2 Si composite. 19) Thus, it is considered that the P3 emission peak is related to Mg 2 Si. RT visible luminescence at 1.97 and 2.14 eV in Mg 2 Si:Al films has also been observed, and it was concluded that the emissions arise from transitions related to interfacial oxide defects.…”

“…Previously, powder forms of Mg 2 Si/Si composites were synthesized, and their structural and optical properties were characterized. 19) Recently, the synthesis of Mg 2 Si nanosheets via Ca atom extraction from CaSi 2 microwalls followed by the incorporation of Mg into the microwalls on Si substrates via thermal annealing in a MgCl 2 /Mg mixed vapor has been reported, and the structural and PL properties of the bundles were characterized. 20) In this study, the detailed structural property of the Mg 2 Si nanosheet bundles was elucidated.…”

Synthesis of MnSi1.7 nanosheet bundles from CaSi2 crystal powders using MnCl2 in molten salt

“…25) Mg 2 Si/Si nanocomposites comprising Si nanosheet bundles and Mg 2 Si deposits have been synthesized; however, homogeneous single-phase Mg 2 Si nanosheets have not been formed using MgCl 2 , which was carefully stored to avoid deliquescence. 26) The Mg 2 Si nanosheet bundles were synthesized by annealing in MgCl 2 /Mg mixed vapor. 27) An additional Mg source was required to form homogeneous single-phase Mg 2 Si nanosheet bundles.…”

Reaction of CaSi₂ and FeCl₂ with additional NaCl to synthesis of β-FeSi₂/Si composites

“…6), 13) Additionally, Mg 2 Si/Si composites containing Si nanosheet bundles and Mg 2 Si deposits were synthesized via heating treatment CaSi 2 and MgCl 2 mixture in a sealed stainless-steel cell under Ar atmosphere at 650 °C. 14) The prepared Mg 2 Si/Si composites affect the emission property of the Si nanosheets. 14) Therefore, the reaction of CaSi 2 and transition metal chlorides mixture is an effective method to acquire various Si-based nanosheets or nanocomposites.…”

“…14) The prepared Mg 2 Si/Si composites affect the emission property of the Si nanosheets. 14) Therefore, the reaction of CaSi 2 and transition metal chlorides mixture is an effective method to acquire various Si-based nanosheets or nanocomposites.…”