講演情報
[11a-E206-8]Lattice Dynamics of Thermoelectric Ba2AgSi3 Studied by Raman Spectroscopy and First-Principles Calculations
〇Thao Dieu Nguyen1, Kimimaru Kajihara1, Taiga Shinohara1, Yoichiro Koda2, Masami Mesuda2, Hikaru Takeshima2, Kaoru Toko1, Takashi Suemasu1 (1.Tsukuba Univ., 2.Tosoh Corp.)
キーワード：
Thermoelectric material、Raman spectroscopy、First-principles calculations
Ba2AgSi3 is a Zintl-phase thermoelectric material that exhibits a high figure of merit (ZT) near room temperature. However, its lattice dynamics and Raman-active vibrational modes have not yet been fully understood. In this study, Raman spectroscopy and density functional perturbation theory (DFPT) calculations were employed to investigate the vibrational properties of Ba2AgSi3 thin films grown by molecular beam epitaxy.Raman measurements at room temperature revealed characteristic peaks at 94.7, 155.2, 243.5, 322.3, and 410.4 cm-1. To assign these modes, Γ-point phonon frequencies and atomic displacement patterns were calculated using the projector augmented-wave method implemented in VASP. The calculated phonon mode at 414 cm-1 agrees well with the strongest experimental Raman peak at 410.4 cm-1. Analysis of the corresponding eigenvector indicates that this mode originates from a collective in-plane vibration of the Si framework, with atomic displacements dominated by Si atoms. The results provide insight into the lattice dynamics of Ba2AgSi3 and demonstrate the usefulness of DFPT calculations for phonon-mode assignment in thermoelectric materials.