CAREER: Novel Ceramic Nanocomposites with Smart Interface Design

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: The CAREER program explores the fundamental interface control in ceramic nanocomposite thin films which allow the design of nanostructures with new or significantly improved materials properties. This study will have direct impact on processing high temperature superconductor (HTS) YBa2Cu3O7-ä (YBCO)-coated conductors with high critical current density in both self-field and in-field for many envisioned applications. The fundamental knowledge gained will also illuminate the interfacial phenomena observed in many other ceramic nanocomposite systems with heterogeneous interfaces, such as microelectronic and optoelectronic devices, thin film solid oxide fuel cells (SOFC), thin film solar cells and etc.. The research program will integrate with the following educational objectives: (1) to develop a teaching model "The Art of Laying Apples" for the PI's thin film classes; (2) to offer a multidisciplinary training to undergraduate and graduate students at Texas A&M University (TAMU), and at Los Alamos National Laboratory and the University of Houston through collaboration; and (3) to disseminate the research results to a much broader audience by (a) involving high school teachers in the research project through a summer research program at TAMU; and (b) involving under-represented groups into materials science and engineering through the Women Engineering Forum and the Women Mentor Program at TAMU and the Los Alamos Summer School (LASS) at the University of New Mexico. TECHNICAL DETAILS: This CAREER project addresses fundamental materials science research on the synthesis, characterization and engineering of heterogeneous interfaces in epitaxial ceramic nanocomposites. This project explores misfit dislocations and associated defects commonly observed at heteroepitaxial interfaces in ceramic nanocomposites, and studies their impacts on material functionalities. The material systems selected for this study are nanolayered and nanoparticle-doped YBCO. The goal is to understand interface control in epitaxial nanocomposite ceramic thin films, with the objective to engineer the interfaces for unique functionalities. First, a thorough microstructural characterization will be performed on nanolayered systems where strong interfacial effects have already been observed. A combination of various atomic-scale characterization tools including high-resolution transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) analysis will be employed to identify misfit dislocations and associated defects at the interfaces. Second, a systematic study to correlate the misfit dislocation density and the flux-pinning property will be conducted on YBCO nanocomposite thin films. Finally, a novel 2D ordered nanoparticle array confined by the 2D misfit dislocation array is proposed. All the YBCO nanocomposite thin films will be prepared by pulsed laser deposition (PLD) at TAMU. Various characterization techniques, such as high resolution XRD, TEM (combined with STEM and EELS compositional analysis), as well as transport property measurements will be utilized to investigate the structural and flux-pinning properties of these YBCO nanocomposite systems.