Luminescence properties and energy transfer of Tb³⁺, Eu³⁺ co-doped YTaO₄ phosphors obtained via sol–gel combustion process

Tantalate is considered as a valuable and efficient luminescence host because of its intense absorption in the ultraviolet area and excellent chemical properties. In this work, a series of pure YTaO₄:Eu³⁺ and/or Tb³⁺ crystals were prepared via a sol–gel combustion method. The morphology, structure, and optical properties of the samples were discussed in detail. The Eu³⁺, Tb³⁺ co-doped YTaO₄ samples are consisted of small spherical particles of around 18 nm. The prepared YTaO₄:Tb³⁺ and/or Eu³⁺ samples exhibit the characteristic wide excitation band around 210–300 nm, the characteristic narrow red emission of Eu³⁺ (⁵D₀ → ⁷F₂) transitions and green emission of the Tb³⁺ (⁵D₄ → ⁷F₅) transitions when excited by UV light. It is focused on the energy transfer processes from the YTaO₄ to Tb³⁺ as well as Eu³⁺ ions and from Tb³⁺ to Eu³⁺ ions of YTaO₄:Eu³⁺/Tb³⁺ phosphors. Color-tunable emissions are realized through adjusting the types of rare earth ion (Eu³⁺ and Tb³⁺) and relative doping concentrations excited by a single wavelength. That is to say, the obtained Tb³⁺ and Eu³⁺ co-doped YTaO₄ phosphors have a promising prospect in lasers, white light diodes (WLED), fluorescent lamp, and field emission display devices, etc.