Investigating ferroelectricity in perovskite oxides: implications for on-surface reactions and photocatalysis

Marta Macyk¹, Andrzej Jasicki¹, Llorenç Albons², Aji Alexander², Jesus Redondo², Igor Sokolovic³, Konrad Szajna¹, Martin Setvin², Dominik Wrana¹, Franciszek Krok¹

¹ Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland

² Department of Surface and Plasma Science, Charles University, Prague, Czech Republic

³ Institute of Applied Physics, TU Wien, Vienna, Austria

Perovskite oxides are well known for their wide range of physical and chemical properties, including strong performance in photocatalysis and piezocatalysis. One of the reasons for this behavior is their ferroelectricity [1]. It was already shown that the ferroelectricity of a perovskite influences the surface structure and its reactivity and this issue is currently widely researched [2]. Despite this, the origin of such properties remains insufficiently understood and awaits further research.

In this presentation the differences in morphology and ferroelectric polarization at surfaces of paraelectric KTaO₃(001) and ferroelectric KNbO₃(001) and BaTiO₃(001) crystals after in-situ and ex-situ cleaving will be shown. Initially, the cleaved surfaces exhibit a (1×1) bulk termination, which evolves into a (2×1) reconstruction upon exposure to water vapor under ultra-high vacuum (UHV) conditions. These surface reconstructions were characterized using AFM and STM imaging, supported by LEED diffraction. Additionally, SEM microscopy and polarization imaging were employed to investigate large-scale ferroelectric domain structures. Complementary open-circuit photocurrent measurements were carried out on powdered perovskite crystals, with the electrolyte temperature modulated to assess the influence of pyroelectric effects on the photocurrent response. This study aims to shed light on the relationship between the ferroelectric properties of perovskite oxides and their surface reactivity.

Fig. 1 a) Room temperature STM image of cleaved KTaO₃(001) surface with (1×1) reconstruction, b) photocurrents of perovskites powders at different temperatures at wavelength 371 nm and potential 800 mV.

References

• [1] Tang, Wenbin, et al., Journal of Materials Chemistry A 10, 7238-7250 (2022)
• [2] Setvin, Martin, et al., Science 359, 572-575 (2018)

The seminar takes place at 15:00 Berlin time (this is 16:00 in Lithuania)

For the link to the seminar check the poster or contact Katharina Rubahn.