T. Wei,Z. Dong,C.Z. Zhao,Y.J. Ma,T.B. Zhang,Y.F. Xie,Q.J. Zhou,Z.P. Li
Er-doped Sr 2 Bi 4 Ti 5 O 18 (SBT- x ) ceramics were synthesized via a solid-state reaction method, and their structure, up-conversion luminescence (UCL), temperature sensing performance and ferroelectric behaviors were investigated. The obtained SBT- x samples crystallize in the polar orthorhombic phase, with space group B2cb. Under 980 nm excitation, bright green and weak red emissions are observed which correspond to the transitions from 2 H 11/2 / 4 S 3/2 and 4 F 9/2 to 4 I 15/2 level, respectively. The optimal doping concentration of Er 3+ in SBT host is determined as 0.08. The critical energy transfer distance ( R c ) is about 20.57 Å and the major interaction mechanism among Er 3+ ions is determined as the d–d interaction. A possible UCL mechanism is proposed in light of the dependence of emission intensities on pumping power. Furthermore, optical temperature sensing properties are also investigated according to the fluorescence intensity ratio (FIR) of green emissions at 527 and 550 nm in the temperature range from 303 K to 573 K. The maximum sensing sensitivity is found to be 0.0042 K −1 . Additionally, the response of SBT- x to external electric field stimuli is also confirmed. It is believed that SBT- x has potential application as optical temperature sensing materials.
Zeping Rao,Yan Yan,Wei Cai,Rong Wang,Zhenhua Wang,Fei Long,Yilong Ma,Chunlin Fu
Constructing ferroelectric hetrojuction and utilizing its piezo-photocatalytic performances is a promising approach for environmental remediation and sustainable energy conversion. However, challenges such as electron-hole recombination and interfacial instability limit the performance of piezoelectric heterojunction photocatalysts. In this study, a novel sandwich-structured heterojunction with a lattice-matched interface constructed by Sr 2 Bi 4 Ti 5 O 18 (SBTO) bismuth Aurivillius phase ferroelectric material and BiOCl (BOC) was developed via a selective etching strategy. This approach minimizes interfacial defects and stress, while ferroelectric polarization modulates charge distribution, enhancing redox activity. Finite element simulations and experimental results demonstrate that the SBTO/BOC heterojunction leverages intrinsic and interfacial electric fields to form dual electron transport pathways, significantly improving charge separation in both bulk and interface regions. The optimized SBTO/BOC heterojunction achieves a piezo-photocatalytic degradation rate of 0.285 min −1 for Rhodamine B, approximately twice that of Sr 2 Bi 4 Ti 5 O 18 under piezo-photocatalysis (0.147 min −1 ) and 13 times higher than photocatalysis alone (0.022 min −1 ). The heterostructure also efficiently degrades dyes, antibiotics, and Cr(VI), offering a robust design for high-performance piezo-photocatalytic systems.
The Aurivillius phase layered perovskite ferroelectric material Sr2Bi4Ti5O18 (SBTO) exhibits spontaneous polarization and piezoelectric properties, which confer significant potential for piezo-photocatalysis. Its ability to enhance electron–hole separation while providing excellent fatigue resistance positions it as a promising candidate in this field. Defects were introduced to improve the structural polarization and photoelectrochemical properties of SBTO. SBTO nanocrystals, featuring a mixed structure of hierarchically ordered mesoporous microflowers and nanosheets, were successfully synthesized via the hydrothermal method. The SBTO sample synthesized at a lower hydrothermal temperature displayed optimal oxygen vacancy concentration and exhibited superior piezoelectric-photo synergistic degradation activity for organic pollutants. Additionally, corona polarization increases the macroscopic polarization of the SBTO photocatalyst, promoting the separation of photogenerated carriers. Finite element simulations confirmed that a single flower-like SBTO structure generates a higher piezoelectric potential compared to a sheet-like morphology. In conclusion, integrating self-assembled hierarchical structure design, ferroelectric polarization, and defect engineering forms an effective strategy for achieving high-performance SBTO-based layered perovskite piezo-photocatalysts.
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