A new sol–gel route towards Nd3+-doped SiO2–LaF3 glass-ceramics for photonic applications

Abstract

Glass-ceramic materials with composition 0.9Nd³⁺–80SiO₂–20LaF₃ were successfully obtained and further heat-treated at 450 °C for 6 h. Stable and homogeneous LaF₃ nanoparticle suspensions with and without Nd³⁺ were first prepared by a chemical route, incorporating polyvinylpyrrolidone (PVP) as dispersant. The suspensions were then concentrated and characterised by XRD, HRTEM and zeta potential, confirming that LaF₃ crystallises as the only phase, with particle size around 16 nm. The suspensions were incorporated in a silica sol to obtain a 0.9Nd³⁺–20LaF₃–80SiO₂ particulate sol, xerogel and glass-ceramic. HRTEM confirmed the homogeneous incorporation of the doped nanocrystals into the SiO₂ matrix without modification of the nanoparticle structure. Rietveld refinement was used to determine the crystallinity and quantity of LaF₃ nanoparticles present in the glass-ceramic after treatment of the particulate sol at 450 °C for 6 h. Luminescence measurements of near infrared Nd³⁺ ion emissions in the lanthanum fluoride nanoparticles and SiO₂–LaF₃ glass-ceramic showed well-structured emission spectra with lifetimes similar to those of theoretical Nd⁺³ in LaF₃ crystals.