Efficient tunable temperature sensitivity in thermally coupled levels of Er3+/Yb3+co-doped BaBi2Nb2O9 ferroelectric ceramic

Er3+/Yb3+ co-doped ferroelectric ceramic BaBi2-0.04-yNb2Er0.04YbyO9 (y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12) are prepared by solid-state method and investigated for their structural and upconversion luminescence properties. High-resolution X-ray pattern investigation confirmed the ceramic's orthorhombic structure. Microstructure of sintered ceramic surface resembles plate-like structures and consists of non-uniform grains that are randomly oriented. Upconversion luminescence (UCL) spectra revealed two prominent green emission bands near 535 and 557 nm and a notable red band at 672 nm, corresponding to a 980 nm excitation wavelength. Decay time measurements support the effective energy transfer from Yb3+ to Er3+ ions. The average lifetime increases with increasing Er3+/Yb3+ doping concentration up to the optimal concentration (y = 0.10). Pump power dependence demonstrates that two photons are required to generate green and red UC illumination. The absolute sensitivity, Sa (0.69% K-1 and 0.58% K-1) and relative sensitivity, Sr (1.1% K-1 and 1.01% K-1) have been recorded for the first time on Er3+/Yb3+ co-doped BaBi2-0.04-yNb2Er0.04YbyO9 ceramic at y = 0.06 and 0.10, respectively, suggesting it is a viable non-contact sensor ceramic whose sensitivity can be tuned by varying dopant concentrations.