Strong photoluminescence and high piezoelectric properties of Eu-doped (Ba_0.99Ca_0.01)(Ti_0.98Zr_0.02)O₃ ceramics

Lead-free luminescent multifunctional (Ba_0.99Ca_0.01)_1−xEu_x(Ti_0.98Zr_0.02)O₃ (x = 0, 0.002, 0.004 and 0.006) (BCEZT-x) ceramics were successfully synthesized using solid state reaction method. The effects of Eu addition on the phase structure and electrical properties of the BCEZT-x ceramics were systematically studied. Results show that orthorhombic–tetragonal (O–T) phase transitions temperature decreases with increasing Eu content, and coexistence of the O and T phases is observed near room temperature (RT) in the composition range of 0.002–0.004. All the BCEZT-x ceramics exhibit high Curie temperature (T _C > 115 °C), especially T _C ≈120 °C for the composition of x = 0.002. The BCEZT-x ceramics at x = 0.002 exhibit excellent piezoelectric properties (d ₃₃ = 400 pC/N and k _p = 52%), due to the coexistence of the O and T phase at RT. Meanwhile, a large strain S _max of ~0.22% is obtained at x = 0.004 for the BCEZT-x ceramics. Moreover, studies on photoluminescence properties of the ceramics shows that luminescence properties are strongly dependent on the doping concentration for the BCEZT-x ceramics. The strongest photoluminescence occurs at x = 0.004 of the BCEZT-x ceramics. Upon the excitation of 465 nm light, all the BCEZT-x ceramics have two intense emission peaks around 593 nm and 616 nm. According to the CIE chromaticity diagram, the ceramics possess a bright yellow light (x = 0.483, y = 0.4991). These results indicate that the BCEZT-x ceramics have significant technological potential as multifunctional devices due to their excellent electric and luminescence properties.