Bi 2 WO 6 lead-free ferroelectrics: microstructure design, polar behavior and photovoltaic performance

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2021-06, Vol.9 (24), p.7539-7544
• Main Authors: He, Xiang, Chen, Chen, Gong, Yunyun, Zeng, Huarong, Yi, Zhiguo
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D1TC01156A

Bi 2 WO 6 (BWO) is a promising ferroelectric material because of its high Curie temperatures and environmentally benign nature. However, the mica-like grain growth habit and large leakage current make it difficult to obtain excellent polar properties when preparing BWO bulk materials by a conventional route. Here, through the precursor morphology control, combined with spark plasma sintering (SPS), we prepared for the first time BWO ceramics with different microstructures: randomly oriented polyhedron grains (R-BWO) and highly aligned plate-like grains (T-BWO). Excellent polar properties are successfully obtained in both kinds of BWO ceramics. In particular, T-BWO ceramics exhibit a large remnant polarization ( P r ) of ∼23.6 μC cm −2 and a piezoelectric coefficient ( d 33 ) of ∼18.2 pC N −1 , almost twice that of the R-BWO ceramics. Moreover, bulk photovoltaic effect investigations indicate that the photovoltaic properties can be modulated through microstructure design, specifically, T-BWO has a short circuit photocurrent of ∼−1.50 nA, which is almost four times that of R-BWO. The underlying mechanisms are further demonstrated by crystal structure and microstructure analysis. This study provides a simple and feasible microstructure engineering approach to manipulate not only the ferroelectricity but also the photovoltaic properties of layer-structured materials.