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MATERIALS ENGINEERING

SEMINAR

“Tunable Multifunctionalities Achieved in Oxide-based Nanocomposite Thin Films”

By

Xingyao Gao

Purdue MSE Ph.D. Final Exam

Advisor: Professor Haiyan Wang

ABSTRACT

Functional oxides indicate the oxides with functionalities, which are recognized as the potential next-generation electronic materials due to their wide variety of crystal structures and properties. Over the past decades, driven by the development of fabrication and device manufacture techniques, more functional oxides with varies applications have been discovered: The biocompatible oxide Al2O3 have been extensively studied in biomedical applications. The ferroelectric oxides with high dielectric permittivities, such as BaTiO3 (BTO), LiNbO3 and Pb(Zr, Ti)O3 (PZT) have been widely used in capacitors, sensors and thermistors. The transparent conducting oxide ZnO and TiO2 have been studied in solar cells. The single-phase multiferroic BiMnO3 and BiFeO3 can be used in data storage devices. The superconducting YBa2Cu3O7 (YBCO) and FeSe have been utilized in high temperature superconductors. The lithium-based oxides LiMn2O4 and LiCoO2 have been extensively studied as the cathode for lithium ion batteries.

In this work, we systematically investigated the tunable multifunctionalities in oxide-based nanocomposite thin films. Four first-time reported nanocomposite systems have been demonstrated with vertically aligned nanocomposite or multilayered structures. By controlling the deposition frequency, film composition and the element in the system, tunable ferromagnetic, ferroelectric, multiferroic, magnetotransport and optical properties have been achieved. The multifunctionality study on these oxide nanocomposite thin films has shown great potential in real life applications including nanoscale memory devices, sensors, spintronics, data storage devices etc.

Date: Monday, November 18, 2019

Time: 9:00 A.M.

Place: ARMS 3115