Professor Kwi-il Park, School of Materials Science and Engineering, Kyungpook National University developed a non-lead piezoelectric material with a core-shell nanostructure in collaboration with Professor Chang Kyu Jeong’s team and Dr. Sung Beom Cho of the Korea Institute of Ceramic and Technology and proved a piezoelectric effect that is more than doubled compared to existing non-lead piezoelectric materials. The results of the study were published in the online edition of “Nano Energy, Impact Factor: 17.881), a renowned journal in the field of nanomaterials and energy, on August 31. The first authors are Yeon-Gyu Kim, a master’s student at Kyungpook National University, and Hyunseung Kim, a master’s student at Jeonbuk National University.
The piezoelectric effect refers to a phenomenon in which electrical changes occur when a substance is deformed. Piezoelectric materials are essential components for most electronic products and are applied to various fields such as sensors, actuators, and energy-generating elements.
Currently, lead titanate zirconate (PZT) is used as a piezoelectric material, but due to restrictions on lead use, which is part of international environmental regulation policies, it is urgent to develop a new non-lead piezoelectric material that can replace lead titanate. Accordingly, non-lead-based piezoelectric materials such as barium titanate (BaTiO3) are attracting attention, but they have not reached the level of practical use due to their lower piezoelectric characteristics than lead-based piezoelectric materials.
Professor Park’s team developed a core-shell nanoparticle structure consisting of barium titanate inside (core) and strontium titanate (SrTiO3) outside (shell). It has been proven that the substitution effect (a phenomenon in which an electrical change occurs inside the material when a strain is applied) can be induced and piezoelectric properties can be improved by continuously changing the concentration of elements from strontium titanate to barium titanate throughout the nanoparticles without a clear boundary between the core and shell.
The core-shell nanoparticles developed by the research team showed a piezoelectric constant (proportional constant between the voltage applied to piezoelectric materials and the resulting deformation) of 49.6 picometers per volt (pm·V-1) more than doubled compared to existing barium titanate nanoparticles. This is the highest figure among all piezoelectric nanoparticles reported to date. In addition, the experimental results were theoretically verified by structurally dynamically calculating the change in strain inside the piezoelectric material through computer simulation.
Professor Kwi-il Park confirmed the possibility of an application technology by manufacturing energy-generating elements using the developed piezoelectric materials. This study is of great significance in that it investigated the correlation between the internal structure of the material and the improvement of the piezoelectric effect based on experimental and theoretical results and presented a new direction for implementing high-performance non-lead piezoelectric materials, he said.