Program

P.65 -- Poster, NCTP-42

Date: Wednesday, 2 August 2017

Time: 08h30 - 10h00

Structural and electronic properties of amorphous TiO$_2$ nanoparticles

Le Thi Hong Diep (1), Ca Nguyen Anh Khoa (1), Huynh Anh Huy (2), Phan Thanh Hung (3)

(1) College of Natural Sciences, Can Tho University, Vietnam; (3) School of Education, Can Tho University, Vietnam; (4) Department of Materials Science, Tra Vinh University, Vietnam.

Density Functional based Tight-Binding (DFTB) method was used to study the structural and electronic properties of six amorphous TiO$_2$ nanoparticles (a-TiO$_2$) with different sizes and shapes. Initial models were cut from the anatase and rutile bulk. Then, all dangling Oxygen, some other Titanium and Oxygen atoms were removed to ensure that Ti:O ratio was 2:1. To received the amorphous TiO$_2$ nanoparticles, the initial models have been annealed from 0 K to 2250K in the linear ramp of 10 ps, followed by equilibration at the constant temperature of 2250 K for 5 ps and cooled down 0 K with an exponential ramp of 15 ps. Structural and electronic properties have been investigated via the Radial Distribution Functions (RDF), coordination number, surface energy and Density Of State (DOS). The findings show that the splitting in RDF of Ti-Ti pair similar to other research about a-TiO$_2$ and the presence of undercoodinate Ti atoms on the surface. The density of state reveal that all a-TiO$_2$ have lower energy gaps than those of crystalline phases, the tail states at the valence band edge are due to the appearance of 2-fold coordinate O atoms; whereas, the tail states at the conduction band edge are localized on 4-fold coordinate Ti atoms. Finally, the research also indicates that the surface energy and the band gap of a-TiO$_2$ strongly depend on their size and shape.

Presenter: Ca Nguyễn Anh Khoa