Reversible modulation of photoenergy in Sm-doped (K0.5Na0.5)NbO3 transparent ceramics via photochromic behavior

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (33), p.19374-19384
• Main Authors: Lin, Jinfeng, Zhou, Yang, Lu, Qiling, Wu, Xiao, Lin, Cong, Lin, Tengfei, Kan-Hao Xue, Miao, Xiangshui, Sa, Baisheng, Sun, Zhimei
• Format: Article
• Language: English
• Subjects: Ceramics; Doping; Energy gap; First principles; High temperature; Illumination; Lead free; Light penetration; Luminescence; Mathematical analysis; Memory devices; Modulation; Niobates; Optical memory (data storage); Optical properties; Photochromism; Photoluminescence; Photons; Piezoelectric ceramics; Piezoelectricity; Transmittance; Vacancies; Xenon; Xenon lamps
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta05936a

By simply doping with a certain amount of Sm3+, opaque lead-free (K0.5Na0.5)NbO3 piezoelectric ceramics were fabricated into transparent/translucent ceramics. The photochromic (PC) behavior and associated reversible transmittance/luminescence modulation were realized via physical means. Upon illumination under a xenon lamp, the maximal decreased values of optical transmittance and luminescence intensity are 36.1% and 49%, respectively. Meanwhile, the colors of all the ceramics turn darker after illumination, and subsequently return to their initial states by thermal stimulus (200 °C for 5 minutes), exhibiting a typical PC phenomenon. Combining experimental and calculation results, it can be found that the PC mechanism is closely related to the vacancy defects induced by both high-temperature sintering and Sm3+-doping. Additionally, the Sm3+ effects on phase structures, microstructures, optical transmittance and photoluminescence properties of the ceramics were systematically studied. The substitution behavior of Sm3+ and vacancy defect concentrations on the energy band gap of the material were unraveled by the first principles calculations to further clarify the corresponding mechanism. The Sm3+-doped (K0.5Na0.5)NbO3 transparent ceramics have potential for application in modulation and conversion of photoenergy, such as in optical memory and photo-switching devices. And the reversible tuning of transmittance in our material is especially attractive for exploring novel transparent PC materials.