Interest in complex metal oxide films has exploded in recent years due to the wide ranging physical phenomena present in these materials, giving rise to potential applications in electronics, energy conversion, and health care applications. While these thin films can now be synthesized with atomic precision, the range of accessible chemistries remains limited. In particular, the ability to substitute different elements such as fluorine or sulfur for oxygen may lead to new electronic, magnetic, or optical functionalities in these films.
Researchers in the groups led by Drexel materials science and engineering professors Steven May and Christopher Li have demonstrated a straightforward and widely accessible route to synthesize thin films in which some of the oxygen atoms have been replaced with fluorine atoms.
Drexel Materials researchers have developed a method to incorporate fluorine anions into oxide thin films, a result that could lead to new ways to control electrical, optical, and magnetic properties in oxide films.
To achieve this result, the team developed an approach that brings together hard and soft materials. The process involves first spin-coating fluorine-containing polymers onto oxide films, then heating the polymer-coated film in an O2 environment. The polymer decomposes, allowing the fluorine to diffuse through the oxide film. The researchers used x-ray spectroscopies and resistivity measurements to show that the addition of fluorine to the oxide films leads to dramatic changes in their electronic properties. It is anticipated that these results will open up a new class of materials—mixed anion complex oxides films—for study and catalyze substantial efforts within the materials research community to explore similar reactions to synthesize new compounds for potential electronic, energetic, or optical applications.
Published in the Journal of the American Chemical Society, “Fluorination of Epitaxial Oxides: Synthesis of Perovskite Oxyfluoride Thin Films," was co-authored by Dr. Eun Ju Moon, postdoctoral researcher in the May group; Yujun Xie, a BS/MS student in the May group; Dr. Eric Laird, recent Ph.D. graduate in the Li group; and Dr. David Keavney of the Advanced Photon Source.