MSE Seminar – Prof. In CHUNG (20 January 2026)

The controlled incorporation of heteroatoms and vacancies into crystalline hosts gives rise to a spectrum of atomic-scale defects whose geometries are dictated by local coordination environments and size mismatches with constituent lattice atoms. These point defects tend to reorganize into extended configurations, ranging from line defects to complex multidimensional domains, which decouple transport properties of charge carriers and phonons uniquely. Independently controlling their behaviors provides a versatile platform for tuning the physical behavior of bulk materials and realizing performance levels that are otherwise inaccessible. A mechanistic understanding of how such defects form and evolve is therefore pivotal for establishing reliable design rules capable of directing specific structural motifs within crystals. Building on this atomic-scale insight, we further connect defect chemistry across mesoscopic and macroscopic length scales to stabilize hybrid lattice architectures that exhibit emergent functionalities.

In this talk, I will discuss our recent advances in formulating predictive guidelines for engineering hierarchical defect structures spanning multiple crystal classes. These approaches enable independent control of the key parameters governing the thermoelectric figure of merit, namely, carrier mobility, carrier concentration, electrical transport, and Seebeck response, culminating in a portfolio of high-efficiency thermoelectric systems that effectively convert waste heat into electrical power.