Recent advances in high-throughput experimentation for combinatorial studies have accelerated the discovery and analysis of materials across a wide range of compositions and synthesis conditions. However, many of the more powerful characterization methods are limited by speed, cost, availability, and/or resolution. To make efficient use of these methods, there is value in developing approaches for identifying critical compositions and conditions to be used as a-priori knowledge for follow-up characterization with high-precision techniques, such as micron-scale synchrotron based X-ray diffraction (XRD). Here we demonstrate the use of optical microscopy and reflectance spectroscopy to identify likely phase-change boundaries in thin film libraries. These methods are used to delineate possible metastable phase boundaries following lateral-gradient Laser Spike Annealing (lg-LSA) of oxide materials. The set of boundaries are then compared with definitive determinations of structural transformations obtained using high-resolution XRD. We demonstrate that the optical methods detect more than 95% of the structural transformations in a composition-gradient La-Mn-O library and a Ga2O3 sample, both subject to an extensive set of lg-LSA anneals. Our results provide quantitative support for the value of optically-detected transformations as a priori data to guide subsequent structural characterization, ultimately accelerating and enhancing the efficient implementation of μm-resolution XRD experiments.
@article{arxiv.2008.06419,
title = {Optical Identification of Materials Transformations in Oxide Thin Films},
author = {Duncan R. Sutherland and Aine Boyer Connolly and Maximilian Amsler and Ming-Chiang Chang and Katie Rose Gann and Vidit Gupta and Sebastian Ament and Dan Guevarra and John M. Gregoire and Carla P. Gomes and R. B. van Dover and Michael O. Thompson},
journal= {arXiv preprint arXiv:2008.06419},
year = {2020}
}