Effects of the Pechini's modified synthetic route on structural and photophysical properties of Eu3+ or Tb3+-doped LaAlO3

Herein, it is reported the Pechini's synthesis of LaAlO₃:Ln³⁺ (Ln = Eu³⁺ or Tb³⁺) varying doping concentration from 1 to 9 at.% to evaluate its influence on structure and luminescence. Sub-micrometric, high-crystalline and monophasic samples with crystallite size smaller than 61 nm were synthesized with activators replacing slightly-distorted LaO₁₂ polyhedra, and occupying two non-equivalent local sites on the surface, and inside them. Upon UV excitation, Eu³⁺-doped phosphors emit at 620 nm while Tb³⁺ ones exhibit dominant wavelength within the green spectral region. The excited state lifetimes lie within 2.5–3.4 ms, and as doping percentage increases, luminescence quenching mediated by exchange coupling energy transfer occurs, leading to the 3 and the 7% as the optimal Eu³⁺ and Tb³⁺concentrations, respectively. Finally, our proposed route increases the Eu^{3+ 5}D₀→⁷F₂ transition relative intensity, compared with others reported, ensuring that this method brings a breakthrough in the optical performance of LaAlO₃-based phosphors.