Size-effects in the ferroelectricity of BaTiO₃ single nanoparticles

It is known that new functionalities can emerge in materials when its physical dimensions are constrained. It has been reported that in thin films, the ferroelectric response of materials can be drastically enhanced via strain effects. Then, a natural approach is to reduce the dimensions even more, in the form of nanoparticles. Here we report on novel properties that emerge when a canonical ferroelectric material, like Barium Titanate, BaTiO₃ (BTO) is synthetized in the form of NPs. We used the hydrothermal method for the fabrication and obtained NPs with a size distribution around 200 nm. Our results indicate that our particles are mostly single phase with a minor contribution of defects or minority phases (less than 1%). Measurements of the piezoelectric response in single Np using PFM microscopy indicate that at these scales, the BTO particles shows an enhancement of the ferroelectric properties compared with bulk. Other novel size-effects will be discussed.