abstract
We performed a systematic analysis of the structure, ferroelectric and photocatalytic activities of Sm and V co-doped Bi4Ti3O12 (SBVT) ceramics. The formation of 3-layered Aurivillius structure and chemically induced strain of SBVT were analyzed by SEM and HRTEM studies. From the results of structural refinements, temperature dependent XRD and Raman spectra we found that SBVT has a distorted orthorhombic structure and transforms to tetragonal in the temperature range of 475-600 degrees C. Raman modes of Bi sites experience the phase transition earlier compared to torsional bending modes of BO6 octahedra. From the results of polarization and piezoelectric strain measurements, we found that SBVT exhibits superior ferroelectric characteristics as well as improved S-33 (0.02 x 10 (3)) compared to other rare-earth doped Bi4Ti3O12 materials reported in the literature. SBVT exhibited fatigue endurance up to 10(8) switching cycles. Such a behavior is attributed to the structural distortions due to the smaller ionic radius of Sm3+ and reduced oxygen vacancies. Local piezoresponse measurements demonstrated imprint characteristics of ferroelectric domains. Furthermore, we assessed the photocatalytic (PC) activity of SBVT - for the first time - in the gas-solid phase, monitoring the degradation of nitrogen oxides (i.e. NO + NO2). Results demonstrated that SBVT was photocatalytically active in the solar spectrum, being able to degrade NOx at ppb level concentration, and exhibited a very stable PC activity (five consecutive PC runs), proving itself suitable for reuse.
keywords
BI4TI3O12 THIN-FILMS; X-RAY-DIFFRACTION; SOL-GEL METHOD; VISIBLE-LIGHT; DOPED BI4TI3O12; ELECTRONIC-STRUCTURE; OPTICAL-PROPERTIES; AIR PURIFICATION; NITROGEN-OXIDES; CERAMICS
subject category
Chemistry
authors
Ramana, EV; Prasad, NV; Tobaldi, DM; Zavasnik, J; Singh, MK; Hortiguela, MJ; Seabra, MP; Prasad, G; Valente, MA
our authors
David Maria Tobaldi
Researcher
Maria Paula Seabra
Assistant Professoracknowledgements
The authors would like to acknowledge the financial support from FCT, Portugal (SFRH/BPD/75582/2010) and COMPETE 2020, financed by national funds of FCT under the project UID/CTM/50025/2013. This work was developed in the scope of the project CICECO - Aveiro Institute of Materials (ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 partnership agreement. MJH acknowledges UID/EMS/00481/2013 project. MKS acknowledges Bilateral Indo-Portuguese 2015/2017 Project and FCT 2013 Investigator Call (IF/00976/2013).