Luminescence studies on SrBi2Ta2O9: Ho3+/Yb3+ phosphors for temperature sensing and optoelectronic devices applications

Abstract

SrBi₂Ta₂O₉: Ho³⁺/Yb³⁺ phosphors were synthesised using a solid-state reaction method. The samples have an Aba2 space group and an orthorhombic structure. The band gaps of the Ho³⁺/Yb³⁺ co-doped phosphors lie within the range of 4.67–4.71 eV. Under UV excitation, singly Ho³⁺ doped phosphors emit green color at 546 nm. Under 980 nm excitation, the SrBi₂Ta₂O₉ phosphors exhibit characteristic green (546 nm), red (662 nm), and NIR (749 nm) emission bands. A two-photon absorption process is responsible for the green and red emissions. The colour coordinates of the Ho³⁺/Yb³⁺ co-doped SrBi₂Ta₂O₉ phosphors lie in the green region. The values of S_R and S_A are 0.0040 K⁻¹ and 0.00144 K⁻¹ respectively that are comparable to the other reported values. The results of this study are encouraging enough to project the as prepared SrBi₂Ta₂O₉: Ho³⁺/Yb³⁺ phosphors for temperature sensing and other optoelectronic devices applications.