Tailoring the Structure and Luminescence of Nanostructured Er³⁺ and Er³⁺/Yb³⁺-Activated Hafnia-Based Systems

Abstract

Nanostructured Er³⁺- and Er³⁺/Yb³⁺-activated hafnium oxide films and nanoparticles were prepared from a stable colloidal suspension and investigated by several techniques such as transmission electron microscopy, X-ray diffraction, dynamic light scattering, atomic force microscopy, Fourier-transform infrared spectroscopy, and photoluminescence. Low roughness and crack-free films were deposited by dip-coating and spin-coating techniques on vitreous SiO<inf>2</inf> and Si substrates. Nanostructured particles were also synthesized. Remarkable structural and spectroscopic differences were observed for hafnium oxide-based materials as a function of the Er³⁺ and Er³⁺/Yb³⁺ concentration. The ⁴I<inf>13/2</inf> → ⁴I<inf>15/2</inf> emission bandwidth and the lifetime of the ⁴I<inf>13/2</inf> metastable state of Er³⁺ was tailored through the rare-earth concentration. The Er³⁺ emission in HfO<inf>2</inf> can be explored for photonic applications.