Structural and NIR photoluminescence studies from Nd3+-doped yttrium niobate: A potential material for photonics

In the present work, an original sol-gel methodology is explored for the synthesis of Nd3+-doped yttrium niobate materials. The main goal was to assess the effect of the dopant concentration on the structural and luminescent properties, specifically in the near-infrared region, aiming for a future biophotonics application. X-ray diffraction and Raman spectroscopy analyses revealed the crystallization of the cubic Y3NbO7 and monoclinic YNbO4 phases, with preferential stabilization of the cubic Y3NbO7, a fluorite-like structure, irrespective of the dopant concentration. All samples presented an intense NIR emission in the second biological window (1000–1500 nm) under excitation at 808 nm (NIR–I excitation), with a prevalence for the 1064 nm emission, indicating the potential application in the biophotonics field. Up to 5 mol% Nd3+ content did not modify the spectral profiles, and the lifetime decay for the 4F3/2 emission level showed that the quenching concentration was 1.78 mol% Nd3+. Higher Nd3+ content revealed broader emission bands, attributed to higher occupation of Y3NbO7 symmetry sites. Emission at NIR-IIa biological window, at 1336 nm, attributed to the 4F3/2 → 4I13/2 was detected indicating the distribution of Nd3+ ions in a low phonon energy environment. The as-reported materials reveal potential application as solid-state lasers and bioimaging probes at NIR-IIa biological window. [Display omitted] •Relatively high quenching concentration.•NIR emission in the transparent biological window.•NIR-IIa emission after NIR–I excitation for bioimaging.