Bi2WO6 lead-free ferroelectrics: microstructure design, polar behavior and photovoltaic performance

Bi2WO6 (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 similar to 23.6 mu C cm(-2) and a piezoelectric coefficient (d(33)) of similar to 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 similar to-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.

Automated summary

This study successfully prepared BWO ceramics with different microstructures using precursor morphology control and spark plasma sintering. Excellent polar properties and photovoltaic properties were obtained, with T-BWO ceramics showing higher remnant polarization, piezoelectric coefficient, and short circuit photocurrent compared to R-BWO ceramics. The findings suggest a simple and feasible microstructure engineering approach to manipulate the ferroelectricity and photovoltaic properties of layer-structured materials.