Program

O.17 -- Oral, NCTP-42

Date: Wednesday, 2 August 2017

Time: 11h10 - 11h30

Theoretical prediction of the new ZnO nanoporous crystalline structures

Vu Ngoc Tuoc1, Nguyen Viet Minh1, Tran Doan Huan2 and Nguyen Thi Thao13

1Institute of Engineering Physics, Hanoi University of Science and Technology,1 Dai Co Viet Rd., Hanoi 100000, Vietnam 2Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA 3Hong Duc University, 307 Le Lai, Thanh Hoa city, Vietnam

Nanoporous framework materials capture a great deal of research attention because of their advantages for a wide range of technology applications in the environment, sensors, shape-selective and bio-catalysis, to name just a few. Within this active research area, computational prediction and theoretical study of these materials are crucial important. We have designed a large family of ZnO nanoporous crystalline structures employing the density functional theory based methods. Our modeling scheme is based on the two approach, "bottom up" and "top down" designs, owing to the advanced nanofabrication techniques. Depend on their secondary building blocks, e.g. ZnO magic cluster cages, nanowire, nanosheet, quantum dot, our modeling crystalline can classified as cage-like hollow, hollow channel, hollow quantum dot nanoporous. For the structural stability, our calculations show that these nanoporous structures could survive in periodic systems without structural collapse, which leads to nanoporous low-density phases of ZnO. Their electronic and thermodynamical properties of the structures, e.g., band structure, free energy and simulated XRD patterns are calculated and discussed in the connection with hollow properties, i.e. shape, size and wall thickness and in the relation with their symmetry. Our results show the convergence of nonlinear depends of bulk modulus on hollow's thicknesses of about of larger than three layers regarding to hollow-to-bulk density ratio and the common rule for the dependences on porosity for different type of hollow topology. We also found that these ZnO hollow phases, if synthesized, would preserve the valuable properties of the ZnO materials, such as wide bandgap semiconducting, piezoelectric and optically transparent, while, at the same time, would possess novel properties as of gap engineering possibility.. Keywords: ZnO nanoporous, structure prediction, density functional theory

Presenter: Vu Ngoc Tuoc