Leading University in Innovation, Research, and Education in Asia
YUHARA Laboratory Is focused on developing new materials designed to create energy-saving devices that address energy challenges.
We are actively involved in the development and evaluation of the structure and physical properties of two-dimensional 14th group honeycomb nano-sheets (post-graphene), which are regarded as promising candidates for new nanomaterials. Furthermore, we are making substantial progress in the synthesis and structural elucidation of oxide quasi-crystal thin films.
Science on Group-14 Nanosheets, Grant-in-Aid for Transformative Research Areas (B), MEXT, Japan
SEMINAR 2025 [New]
Growth of quasicrystal-related and honeycomb structure of Ce-Ti-O ultra-thin films on Pt(111)
Speaker : Xu Li, Nagoya University, Japan
Date : Thursday, 20 Feb, 11am
Location : NUS S11-02-07
Moderator : A/Prof Wang Xuesen, Faculty of Science, NUS
Abstract
Quasicrystals, which don’t have translational periodicity, but have rotational symmetries such as 5-fold, 10-fold, or 12-fold, were discovered in 1984 by D. Shechtman. Recently, oxide quasicrystal (OQC) with dodecagonal clusters was reported to be prepared from ultrathin Ba-Ti-O and Sr-Ti-O films on Pt(111). In my talk, the rare earth element Ce is used to replace the Ba/Sr metallic elements, to prepare the Ce-Ti-O ultra-thin films on Pt(111).
The Ce-Ti-O ultra-thin film was prepared by depositing Ce and Ti on Pt(111), following with annealing in oxygen atmosphere and vacuum. An arrangement of dodecagonal clusters consisted of triangles and squares were locally observed. In addition, the appearance of trapezoids led to the structure to be recognized as an OQC-R structure.
By additional Ti deposition on OQC-R ultra-thin film, a (√3×√3)R30˚ superstructure is observed, regarding as a honeycomb superstructure by STM image. Furthermore, density functional theory calculations and photoelectron holography were used to confirm the atomic structure.
SEMINAR 2024
Growth of group 14 elemental post-graphene materials
Speaker : Junji Yuhara, School of Engineering, Nagoya University, Japan
Date : Tuesday, 13 Aug, 3PM
Location : NUS Conference room: S11-02-07
Host : Prof Andrew Wee, Faculty of Science, NUS
Abstract
The synthesis and characterization of post-graphene materials have been intensively studied to utilize novel two-dimensional (2D) properties. Most studies adopted molecular beam epitaxy to synthesize 2D materials grown on clean, crystalline surfaces. In my talk, I will talk on the epitaxial growth of (1) germanene, (2) stanene, lateral heterostructure, and (3) plumbene by segregation and deposition methods.
Germanene is formed on Ag(111) thin films grown on Ge(111) after annealing, where Ge atoms segregate to the surface. Low-energy electron diffraction and scanning tunneling microscopy images confirm its incommensurate spots and honeycomb structure with minimal buckling.
Stanene is synthesized on an Ag2Sn surface alloy by Sn deposition. The alloy’s lattice closely matches that of free-standing stanene, making it ideal for large-area planar stanene growth due to its chemical inertness to Sn atoms.
Plumbene is grown on Pd1-xPbx(111) alloy surfaces by depositing Pb atoms, which dissolve into the Pd crystal and segregate upon annealing. STM images show a unique morphology resembling the Weaire-Phelan structure from Beijing’s Olympic “WaterCube”.
Contact :
Department of Energy Engineering, School of Engineering, Nagoya University
Email : j-yuhara@nagoya-u.jp