Collaboration to Introduce Neutron Diffraction to Enhance Research Education by increasing Lab Access (CINDERELA)

Dr. Robert L. Green¹, Professor

Dr. Thomas Watkins², Senior Research Staff

1: Alabama State University, Montgomery, AL 36104

2: Oak Ridge National Laboratory, Oak Ridge, TN 37831

Alabama State University (ASU) and Oak Ridge National Laboratory (ORNL) will collaborate to increase the research capabilities of ASU’s chemistry degree program focusing on solid-state inorganic chemistry research.  One aim is to engage underrepresented minority undergraduate students in scientific research while providing research opportunities outside of the classroom.  This effort also serves as a recruiting tool to increase the viability of ASU’s chemistry degree program as well as providing qualified candidates for graduate work to our nation.  The partnership with ORNL will provide access to state of the art research tools and professional networking opportunities to enrich the educational experience and have a profound impact in preparing students to advance science. The ASU-ORNL collaboration will investigate the following objective:  What is the accuracy of bond valence sum (BVS) to predict the crystallographic locations of trivalent rare-earth (RE³⁺) substitutions hosted within layered fluoride-based anti-Perovskites by synthesizing the same, determining their crystal structure and measuring the corresponding photoluminescence of these phosphors.  An emphasis will be placed on the synthesis, advanced characterization and computer modeling of RE³⁺ substituted and non-RE containing oxyfluoride phosphor materials. These layered oxyfluoride host structures have three distinct positions that can accommodate cationic substitutions to tailor the emission spectrum and create a desired lighting phosphor. Density functional theory (DFT) will guide synthesis and provide predictive modeling in RE³⁺ substituted samples to determine the stability of the structure based on the BVS.  The photoluminescence (PL) emission of the resulting phosphors will correlate to the structure stability of DFT modelling.  Study of crystallographic structure of air annealed and reduced oxyfluoride samples will help identify the mechanism of the increased PL emission and stability.  X-ray diffraction will be used as an essential technique to monitor and identify phases within the synthetic process.  Neutron and synchrotron diffraction techniques will further clarify atomic positions within the crystal structure. Refined bond distances and angles from Rietveld analysis will provide experimental bond valence sums and global instability indices for synthetic products from ASU, which will, then be compared with computationally modeled bond valence values from collaborators at ORNL. A joint publication of research results in peer-reviewed journals by undergraduate students in chemistry is expected. CINDERELA funding will effectively allow for chemistry-focused research training for underrepresented African-American undergraduate students, which make up 98% of the enrollment in the chemistry degree program at ASU. Additionally, we will focus on developing the “whole” student by providing a nurturing and challenging educational and professional environment that is scholarship focused. Finally, engaging students and encouraging participation in more advanced research efforts at the undergraduate level will positively influence our teaching efforts and shift the culture of our departments.