Scale and size effects in Ba-based ceramics (SEBA)

Project code: PN-III-P1-1.1-PD-2021-0531
Project number: PD82/2022
Funded by the Executive Unit for Financing High Education, Research, Development and Innovation, CNCS – UEFISCDI 


Ferroelectric ceramics attracted an increasing interest due to their unique properties and wide use in many devices. Ferroelectricity arises from long-range ordering of elemental dipoles, which determines the appearance of a macroscopic polarization, while by confining the system in a small volume, a disturbance of the polar order is produced, which causes the disappearance of ferroelectric order. Up-to-date existing data indicate a critical grain size (GS) of ~10 nm for ceramic materials and a critical thickness of 2 − 3 nm in the case of epitaxial thin films. While in the case of pure BaTiO3 (BT) ceramics, the size-dependent properties have been extensively studied, the effect of GS on the functional properties of BT-based solid solutions has only recently been addressed. These studies reported only some limited ranges for GSs and a systematic study of size effect on the dielectric, ferroelectric and dc-tunability properties of such solid solutions with GSs from 100 nm to tens of micrometers has never been performed.

In the present project we propose to prepare and investigate the functional properties from mesoscale to macroscale of BaMxTi1-xO3 ceramics (M = Zr / Hf / Ge / Ce) with GS from nm to tens of μm, to elucidate if a critical size exists with enhanced dielectric/ferroelectric properties and to understand the role of intrisic/extrinsic contributions to functional properties in nanostructured dense BaMxTi1-xO3 ceramics.