Microstructural comparison between PMMA-SiO2 and PMMA-TiO2 hybrid systems using Eu3+ as ion-probe luminescence

Abstract

Organic-inorganic Eu3+-doped PMMA-SiO2 and PMMA-TiO2 hybrid systems were synthesized by sol-gel. The doping ions were used as ion-probe luminescence to analyze the differences in the microstructure of the hybrid matrices. The local symmetry environment of the Eu3+ ions in the hybrid matrices was described by the asymmetry parameter (R), defined as the intensity ratio of the 5D0 → 7F2/5D0 → 7F1 transitions. The photoluminescence of PMMA-SiO2 with quenched emission and lower R is consistent with a symmetric, hydrated environment surrounding the Eu3+ ions. Meanwhile, the higher value of R and the higher emission intensity, observed for PMMA-TiO2, reveal a lower symmetric environment of the Eu3+ ions. Furthermore, the emission and excitation bands of the 5D0−7F0 transition shows a red shift in the PMMA-TiO2 spectra, indicating higher Eu-O covalence degree. The calculated values of the Judd-Ofelt parameters are in agreement with the higher Eu-O covalence degree in this hybrid material.