Dr. Zhongwu Wang [Cornell University, New York, USA]

Title: Nanocrystal Assembly, Superlattice Decoding and Controllable Processing for Materials Design

Time: 15:15 - 16:15, Wednesday July 11, 2018

Place: Conference room 410, HPSTAR (Shanghai)

Host: Jinlong Zhu

Polycom: 02120004

Abstract:

Cornell High Energy Synchrotron Source, Cornell University

Materials-by-Design appears as one of the most important and sought-after goals to make materials discovery and fabrication in a controllable way. Using colloidal nanocrystals (NCs) as designable building blocks, we have been making effort to understand and design nano-based periodic structure with desired property, and thus to make controllable ways of processing and engineering to create complex architectures with increased structural stability and functionality.

In this talk, I will briefly touch the concept of materials design and introduce several key components that we need to work on. Then, I will slightly address how both small and wide angle X-ray scattering (SAXS/WAX) techniques are synchronized with various spectroscopic probes to resolve nanocrystal-based scientific issues. Using several examples, I will talk about synchrotron-based discovery and construction of nanocrystal assembled pathway from the early nucleation to late growth and subsequent transformation. Taking advantage of our newly developed “supercrystallography” approach, I will document the structural decoding of NC-assembled supercrystals at levels from atomic through nano to mesoscale. With such structural aspects of both translational and orientational ordering, I will discuss the controllable processing of such superlattices (i.e. pressure and temperature) to create new category of functional materials with higher order of nano-based architectures. To conclude the talk, I will also provide examples to show the application of such materials in device fabrication and technological development.

Biography of the Speaker:





Zhongwu Wang, Ph.D. and Staff Scientist

Cornell High Energy Synchrotron Source (CHESS)

Wilson Laboratory, Cornell University, Ithaca, New York

Phone: 607-255-3551 (office); Email: zw42@cornell.edu.

Research Interests:

High pressure phenomena and properties of materials (including one completely new direction of high pressure single supercrystallography); Colloidal nanocrystal (serving as atom-equivalents or artificial atoms) assembly and underlying mechanisms of nucleation and growth and property manifestation; Large single supercrystal growth of nanocrystal assembly with both translational and orientational ordering; Precise structural reconstruction of nanocrystal-assembled supercrystals at unprecedented levels from atomic through cluster and nano to mesoscale; Mesoscale science and resultant novel phenomenon/property and the development of mesoscale new concepts; Developments of synchrotron-based supercrystallography, SAXS/WAXS-based 3D structural reconstruction, and single-crystal (including supercrystal) based PDF approach with dramatically improved accuracy; In-situ build-up of materials structure-property-processing relationships at real environments of pressure and temperature, and in-operando conditions; Designer solid and controllable processing/engineering towards scalable fabrication of advanced functional materials with tailored structures and properties for device application.