Demonstration of the hierarchical arrangement of persistent luminescent microparticles in direct doping-prepared photonic glasses using second-harmonic generation microscopy

Abstract

Using three-dimensional (3D) second-harmonic generation (SHG) scanning microscopy, we unravel the formation and distribution of distinct and highly localized persistent luminescent (PeL) microparticles of varied hierarchical levels in glasses prepared using the direct doping method. The PeL microparticles were added in the glasses at different doping temperatures and the glasses were quenched after different dwell time. The SHG maps of the PeL microparticles in the glass, prepared with a doping temperature of 975°C and a dwell time of 3 min, reveal grating-like microscopic domains. This suggests that a large arrangement of PeL crystals spanning several micrometers in three dimensions is manifested by the imbued PeL microparticle. In contrast, the SHG maps of the PeL microparticles inside the glass prepared at doping temperature of 1025°C and dwell time of 10 min, show the existence of single, highly localized and most importantly, submicrometer-sized PeL crystals. These findings substantiate well with the expected behavior of the PeL microparticles in glasses and their physical disintegration in the form of nanoparticles at high doping temperatures and dwell times. The SHG microscopy technique is shown to circumvent the fundamental challenges of traditional and usually destructive imaging methods to detect and visualize PeL nanoparticles in a glass matrix and expected to open a new avenue to evidence the presence of crystals in glasses.