Tuning the structural, optical, photoluminescence and dielectric properties of Eu²⁺-activated mixed strontium aluminate phosphors with different rare earth co-activators

Abstract

Different phosphor colors of SrAl_xO_y: Eu ²⁺_0.01 , R ³⁺_0.01 (R = Er³⁺, Tm³⁺ and Tb³⁺) nanopowders and pellets have been synthesized via citrate combustion technique. XRD results revealed that monoclinic SrAl₂O₄ was the major phase and hexagonal SrAl₁₂O₁₉ was the minor phase. Meanwhile, Field emission SEM images showed hollow cylindrical-like shape structures filled with the large number of nanorods for the SrAl_xO_y: Eu ²⁺_0.01 , Tb ³⁺_0.01 sample. The values of measured band gap energy and calculated refractive index were mainly dependant on the ionic radius of R³⁺ co-doping ion. The PL emission spectra and afterglow properties were strongly affected by the lanthanide type (R³⁺). For instance, Eu²⁺-SrAl_xO_y sample achieved the maximum dielectric permittivity (έ) ~16.77 and dielectric loss (tanδ) ~0.19 at the microwave frequency region (1 GHz). Meanwhile, Tb³⁺, Eu²⁺-SrAl_xO_y sample was possessed the minimum dielectric permittivity (έ) ~1.36 and dielectric loss (tanδ) ~0.0002 at the radiowave frequency region (100 MHz).