Synthesis of Polar Ordered Oxynitride Perovskite

TL;DR

This paper reports the successful synthesis and experimental validation of a polar ordered oxynitride perovskite, YSiO2N, confirming theoretical predictions of its structure and nonlinear optical properties.

Contribution

It is the first experimental demonstration of a polar ordered oxynitride perovskite, validating prior DFT predictions.

Findings

YSiO2N is polar and exhibits strong nonlinear optical properties.

Experimental results match DFT predictions of structure and properties.

The synthesis method combines diamond anvil cell and in-situ laser heating.

Abstract

For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen are replaced by nitrogen, but a polar ordered oxynitride has never been demonstrated. Caracas and Cohen studied possible ordered polar oxynitrides within density functional theory (DFT) and found a few candidates that were predicted to be insulating and at least metastable. YSiO2N stood out with huge predicted polarization and nonlinear optic coefficients. In this study, we demonstrate the synthesis of perovskite-structured YSiO2N by using a combination of a diamond anvil cell and in-situ laser heating technique. Subsequent in-situ X-ray diffraction, second harmonic generation, and Raman scattering measurements confirm that it is polar and a strong nonlinear optical material, with structure and properties similar to those predicted by DFT.