Effects of Defect Density on Optical Properties Using Correlative Cathodoluminescence and Transmission Electron Microscopy Measurements on Identical PrNbO₄ Particles

Understanding the optical properties of lanthanide niobates is essential to improve the development of these materials. In this study, we investigated PrNbO4 powder particles with different density of twins which influences the intensity of the emission lines. The twins form during synthesis of these particles based on a solid-state route. A correlative approach using backscattered electron imaging, cathodoluminescence measurements, focused ion beam lift out, and aberration-corrected transmission electron microscopy was used at the same location within the particles. Emission lines were acquired by using a cathodoluminescence spectrometer attached to a scanning electron microscope on two regions including twinned and twin free areas. The results were compared and indicate that the areas with higher density of twins have more intense emission lines. The reason for the improved luminescent properties is the perturbation of the energy states caused by the defects which promotes the occurrence of the parity forbidden f-f transitions.