Rachel Sherbondy

New Cerium-Containing Nitrides Perovskites

BIO:

Rachel Sherbondy is a second year PhD student at the Colorado School of Mines in the Metallurgical and Materials Engineering Department under the advisement of Dr. Geoff Brennecka. She graduated with her B.S. in Materials Science and Engineering from Penn State University in 2017. In her spare time, she enjoys running, hiking, and baking sweets.

ABSTRACT:

The perovskite family of materials is well known for uses across a wide range of fields, including ultrasonics, photovoltaics, and solar water splitters. As the uses for materials in this family grow, there are increasing reports of new compounds that take this structure. Oxide perovskites for ultrasonics have been used since the 1960’s in devices such as fish finders or even advanced medical ultrasound. The more recent application of photovoltaic materials involve hybrid organic-inorganic structures, like the prototype methylammonium lead iodide (MAPI). Solar water splitters use oxynitride or oxides. However, there is very little research done into the pure nitride perovskite family.

The formula unit for a perovskite material is ABX3 where A is a lower charge cation, B is a higher charged cation, and X is the anion. These materials frequently have a high dielectric permittivity due to the ability of the highly charged B cation to shift within the structure and displace the centers of positive and negative charge. If the material takes a structure in the perovskite family that lacks a center of symmetry, then it may also be piezoelectric, which means that an applied electric field can deform the material. This is the property around which ultrasonic perovskites are built. Materials in the perovskite family also may be ferroelectric, which means that they have regions with a spontaneous dipole which can be reoriented under an applied electric field. These properties make perovskites a promising field in which to search for new compounds.

In this study, new compounds were created using a high-throughput approach to making thin films. When examined by diffraction, the films appear to have a single phase present, and the characteristic peaks of the diffraction pattern indicate that they belong the perovskite family.