Deciphering phase evolution in complex metal oxide thin films via high-throughput materials synthesis and characterization

Discovery of structure-property relationships in thin film alloys of complex metal oxides enabled by high-throughput materials synthesis and characterization facilities is demonstrated here with a case-study. Thin films of binary transition metal oxides (Ti-Zn) are prepared by pulsed laser deposition with continuously varying Ti:Zn ratio, creating combinatorial samples for exploration of the properties of this material family. The atomic structure and electronic properties are probed by spatially resolved techniques including x-ray absorption near edge structures (XANES) and x-ray fluorescence (XRF) at the Ti and Zn K-edge, x-ray diffraction, and spectroscopic ellipsometry. The observed properties as a function of Ti:Zn ratio are resolved into mixtures of five distinguishable phases by deploying multivariate curve resolution analysis on the XANES spectral series, under constraints set by results from the other characterization techniques. First-principles computations based on density function theory connect the observed properties of each distinct phase with structural and spectral characteristics of crystalline polymorphs of Ti-Zn oxide. Continuous tuning of the optical absorption edge as a function of Ti:Zn ratio, including the unusual observation of negative optical bowing, exemplifies a functional property of the film correlated to the phase evolution.

Automated summary

This study demonstrates the discovery of structure-property relationships in thin film alloys of complex metal oxides through high-throughput materials synthesis and characterization facilities. Thin films of binary transition metal oxides (Ti-Zn) were prepared with continuously varying Ti:Zn ratio, and the properties of this material family were explored. Spatially resolved techniques such as XANES and XRF were used to probe the atomic structure and electronic properties, and multivariate curve resolution analysis connected the observed properties with the structural and spectral characteristics of crystalline polymorphs of Ti-Zn oxide.