Photoluminescence, electrical properties and electron band structure of (Ho, Yb)3+ co-doped SrBi4Ti4O15 multifunctional ceramics

SrBi3.992-xHo0.008YbxTi4O15 (x = 0.000, 0.002, 0.004, 0.006, abbreviated as SBHT-xYb) multifunctional ceramics were fabricated by solid-phase reaction method. Their electrical, luminescence properties and electronic band structure were investigated. At x = 0.002, samples exhibit enhanced piezoelectric coefficient (d(33) = 19 pC/N) and optimal thermal stability. Thermal annealing behavior shows that the d(33) of SBHT-0.002 Yb at 460 degrees C remains 84% of its d(33) value at room temperature (RT). Excited by 980 nm laser, the SBHT-xYb samples show two emission bands. Green emission at 548 nm and red emission at 658 nm are considered to be the transfer of two excited states S-5(2) and F-5(5) to the ground state I-5(8) of Ho3+ ions, respectively. Furthermore, the electron band structure of SBHT-xYb ceramics was calculated using density functional theory (DFT). It is found that the energy consumed for electron transition first decreases and then increases, while the 4f orbital contributions of (Ho, Yb)(3+) ions are enhanced by doping with Yb3+, elucidating the change in luminescence intensity in terms of microscopic mechanism. All the above results manifest that SBHT-xYb ceramics are good potential alternative for luminescence and piezoelectric properties integrated devices.