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

Abstract

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories, optical switches and bio-imaging. However, those materials are basically opaque. In this work, we prepared a PC luminescent [Formula: see text][Formula: see text]NbO3-based ferroelectric transparent ceramic by modifying with [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], which not only have good optical transmittances ([Formula: see text]60% at 900[Formula: see text]nm), moderate ferroelectric properties and down-conversion photoluminescence (PL) properties, but also exhibit reversible PC behavior. After the illumination by xenon lamp, the colors of the ceramics change from pale green to gray, and then reversibly recover to their initial state via thermal stimulus (200∘C for 10[Formula: see text]min). Interestingly, both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process. The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices.

Expedient Red Emitting and Transparency Dual Modulation in KNN-Based Transparent Ceramics via Sensitive Photothermochromic Behavior

“…According to the transmittance spectra (Figure 3a), it is precisely because KNNEB-1125 has the strongest absorption for 980 nm excitation that it can convert to the strongest emission (Figure 5a). Consistent with recent reports, 18,20 the KNNEB transparent ceramics also exhibit PL quenching behavior based on PTC phenomenon. Intuitively, the shape/position of the PL peaks of the KNNEB transparent ceramics, consistent with the optical transmittances (Figure 4a−c), has basically not changed after irradiation through a UV light (395 nm, 300 W, 1 min).…”

“…Consistent with recent reports, , the KNNEB transparent ceramics also exhibit PL quenching behavior based on PTC phenomenon. Intuitively, the shape/position of the PL peaks of the KNNEB transparent ceramics, consistent with the optical transmittances (Figure a–c), has basically not changed after irradiation through a UV light (395 nm, 300 W, 1 min).…”

“…Figure d–f show that the modulation of the red emitting of the KNNEB transparent ceramics exhibits excellent stability under the continuous alternating of irradiation (395 nm, 300 W, 1 min) and heat treatment (200 °C, 10 min) for 10 cycles, as stable as the modulation of transmittance analyzed above. Taken together, compared with the previously reported luminescent KNN transparent PC ceramics, ,,− the KNNEB ceramics hold absolute advantages in terms of the excellent transparency and the modulation of optical properties, which are manifested in the following two aspects: (1) moderate contrast of optical properties based on PTC behavior while ensuring excellent transparency (Figure ) and (2) unique high-purity red emitting characteristics and corresponding modulation. These notable properties create application prospects for the KNNEB transparent ceramics in the fields of multifunctional transparent sustainable warning equipment and optical storage materials.…”

“…More meaningfully, they also exhibit good reversibility of optical transparency during the coloration–decoloration processes by continuous alternating irradiation from a UV light (395 nm, 1 min) and heat treatment (200 °C, 10 min) for 5 cycles. The above-mentioned coloration–decoloration process is a typical photo­thermochromic (PTC) phenomenon reported at present, which is inseparable from the existence of defects, especially for oxygen vacancies defects generated during doping and volatilization of alkali metal ions. ,− The degree of transmittance reduction can be well described by the following equation: where T 0 and T 1 are the transmittances before and after irradiation. Defects are the dominant factor in the process of coloration.…”

Significantly Photo‐Thermochromic KNN‐Based “Smart Window” for Sustainable Optical Data Storage and Anti‐Counterfeiting

“…[33] To date, the PTC behavior of the Er-KNLN ceramics (especially for Er-KNLN-1150 and Er-KNLN-1165) can compete with the opaque luminescent ferroelectric PC ceramics (Figure 5a), [3,14,15,17,18,31,34,35] simultaneously, their excellent transparency and modulations of optical properties exhibit prominent advantages compared with the previously reported luminescent KNN transparent PC ceramics (Figure 5b). [13,19,20,[36][37][38][39]…”