Reversible luminescence modulation of Ho‐doped K_0.5Na_0.5NbO₃ piezoelectrics with high luminescence contrast

Abstract

A significant luminescence modulation behavior based on photochromic reactions was observed in Ho3+‐doped (Na0.52K0.48)0.92Li0.08NbO3 ceramics, fabricated by the conventional solid‐state reaction method. Under visible light irradiation (407 nm) for 20 second, the samples changed pale gray from initial pale green, and returned to their original color by a thermal stimulus of 230°C for 10 minutes, showing typical photochromic phenomenon. Under 453 nm excitation, the samples exhibited strong green emission at 551 nm. Interestingly, their green emission intensity can be effectively tailored by controlling photochromic reaction processes (irradiation wavelength and time), and the luminescent modulation ratio (ΔRt) reaches up to 77%. And, the ΔRt value has no any obvious degradation after 10 cycles by alternating visible light irradiation and thermal stimulus, showing excellent reversibility. These results make it potential applications in many fields as a kind of multifunctional material.

Eu-doped K0.5Na0.5NbO3-(Ba,Sr)TiO3: A novel lead-free luminescent ferroelectric transparent ceramic with reversible photochromism

“…Additionally, the generation of impurity phases can be due to the volatilization of alkali metal ions (K þ /Na þ ) in the high-temperature sintering environment (i.e., 1205 ○ C for 4 h) and then the stoichiometric deviation. [22][23][24] From the perspective of crystal symmetry, compared with the orthorhombic phase of pure KNN, the tetragonal phase of xEu-KNNBST is closer to cubic one, benefitting in reducing optical anisotropy and light scattering. Therefore, the optical transmittances of the xEu-KNNBST ceramics significantly improve.…”

Photochromism‐induced light scattering and photoswithing in Er doped (K,Na)NbO3 transparent ceramics

“…15 In our previous studies, we found that KNN-based ceramics are very sensitive to visible light irradiation, showing a typical photochromism. 16,17 This photochromic behavior no doubt would bring about strong light scatting in transparent ferroelectric ceramics, which is very important for deeper understanding of such photo-induced scattering performance. However, there are only a few studies on the light scattering effect from photochromic reactions.…”

Quantitative analyses of electric field–induced phase transition in (Na, K)0.5Bi0.5TiO3:Eu ceramics by photoluminescence

“…The rare‐earth (RE) ions–doped ferroelectric ceramics is becoming an interesting field because of the coupling of luminescence and electrical properties . Many ferroelectric ceramics doped with RE ions show efficient PL properties while maintaining their excellent electrical properties, making them multifunctional materials .…”

“…The rare-earth (RE) ions-doped ferroelectric ceramics is becoming an interesting field because of the coupling of luminescence and electrical properties. [1][2][3][4] Many ferroelectric ceramics doped with RE ions show efficient PL properties while maintaining their excellent electrical properties, making them multifunctional materials. [5][6][7] It is generally believed that the optimal properties of ferroelectric ceramics can be achieved under condition of multiphase coexistence, 8 such as morphotropic phase boundary (MPB).…”