In collaboration with colleagues from Switzerland and Japan, we identified for the first time the accumulation of charged defects at domain walls in ferroelectric BiFeO3. This finding explains the p-type hopping conduction at domain walls and thus represents the missing piece for explaining the intriguing electrical properties of domain walls in ferroelectrics. The study was published in Nature Materials with a 2015 impact factor of 38.89, which currently makes it one of the highest-impact scientific journals. The entire study was conceived and experimentally implemented at Slovenian research institutions (Jozef Stefan Institute and National Institute of Chemistry).
COBISS.SI-ID: 29936679
Electromechanical properties of ferroelectrics are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Systems with MPBs between polar and non-polar phases, which are distinctly different from “classical” PZT-like MPBs between two polar phases, have recently been theorized as having great promise. While such an MPB was identified in lead-free rare-earth (RE) modified BiFeO3 thin films, synthesis challenges have prevented its realization in ceramics. Overcoming these, we demonstrate with this study a comparable electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm-modified BiFeO3. The effect arises from ‘dual’ strain mechanisms, namely ferroelectric/ferroelastic switching and a previously unreported electric-field induced transition of an anti-polar intermediate phase. The paper was published in Scientific Reports (IF 5.228, JCR 2015) issued by the prestigious Nature Publishing Group.
COBISS.SI-ID: 29234727
The paper, which was published in a high-impact journal (Advanced Functional Materials, IF 11.382, JCR 2015), explains the relationship between the nanoscale electrical conductivity at domain walls in BiFeO3 and its macroscopic piezoelectric response. A combination of electromechanical measurements both at the nanoscale and macroscopic (millimeter) scale revealed that the conductivity localized at the domain walls in BiFeO3 has a marking effect on the mobility of these walls and thus on the macroscopic piezoelectric behaviour. This new mechanism, referred to as the “nonlinear piezoelectric Maxwell-Wagner effect”, may be present in ferroelectrics containing boundaries or interfaces that can both displace under external fields and exhibit enhanced electrical conductivity (such as domain walls in BiFeO3). The paper is accompanied with an inside front cover authored by the researchers from the Electronic Ceramics Department K-5.
COBISS.SI-ID: 28359975
In collaboration with researches from Australia and Switzerland we published a paper in the high-impact journal ACS Applied Materials & Interfaces (IF 7.145, JCR 2015) entitled “Self-Poling of BiFeO3 Thick Films”. The study reveals an intriguing phenomenon in which BiFeO3 thick films, after being cooled through the ferroelectric-paraelectric phase transition at ~820°C, develop a strain gradient, resulting in a self-poling effect and a drastic change of the microstructure from equiaxed to columnar grain morphology.
COBISS.SI-ID: 29643559
In this review paper, published in the Journal of the American Ceramic Society, the leading journal in the field of ceramic materials, we present a comprehensive overview of the processing, electrical and electromechanical processing of BiFeO3 ceramics. The paper is a result of a collaborative study between the Slovenian researchers and the University of Florida (USA), North Carolina State University (USA), University of New South Wales (Australia) and Swiss Federal Institute of Technology (Switzerland). Since its publication in July 2014 the paper has been cited 55 times (source: Wos) and is accompanied by a journal cover image, which was designed by the Slovenian group.
COBISS.SI-ID: 27790375