Improving the photostriction of Na0.5Bi0.5TiO3-based lead-free ceramics by Bi nonstoichiometry. (1st May 2023)

• Record Type: Journal Article
• Authors: Ren, Z.H.; Jain, Aditya; Shi, L.N.; Zhou, H.Z.; Chen, F.G.; Wang, Y.G.
• Is Part Of: Ceramics international. Volume 49(2023)Part A
• Page Start: 14090
• Page End: 14100
• Publication Date: 2023-05-01
• Subjects: Photostrictive -- Non-stoichiometry -- Oxygen vacancy -- Ferroelectrics; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.12.290
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: In the present work, Bi non-stoichiometry is used to control oxygen vacancy concentration and the ferroelectric to relaxor phase transition temperature ( T F-R ) to optimize photostriction performance. Large photostriction (1.8 × 10 −3 ) and high photostriction efficiency (1.7 × 10 −11 m 3 /W) were observed in 0.95Bi0.52 (Na0.81 K0.19 )0.5 TiO3 -0.05Ba(Ti0.5 Ni0.5 )O3-δ ceramic. The non-stoichiometric increase of Bi does not change the band gap of the material, but leads to the decrease of oxygen vacancy concentration, which leads to more effective photo-generated carriers interacting with lattice and improves photostriction macroscopically. Bi non-stoichiometry also induces T F-R to drop to near room temperature, and microscopically the decoupling of the A-O bond, which makes the unit cell change from a limited polar state to a cubic-like state and thus the polarizability of the unit cell increases. Therefore, under the action of photo-generated carriers or photo-generated electric field, the lattice changes from a nonpolar state to a polar state and the lattice distortion is produced, which may be accompanied by the re-coupling of the A-O bond, thus optimizing photostriction macroscopically. Laser power-dependent Raman spectra show the blue shift of the A-O bond mode and the red shift of the TiO6 mode, indicating the increase in lattice polarity and deformation caused by the re-coupling of the A-O bond and the distortion of the TiO6 octahedron. This work provides a new way for designing ferroelectric materials with excellent photostrictive performance.