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Peking University of Technology's important progress in piezoelectric metamaterial research
[ Instrument Network Instrument Development ] For nearly half a century, active devices represented by integrated semiconductors and active and passive devices based on various functional ceramic materials have profoundly changed human society. As a widely used distributed intelligent sensing, transducing and energizing, and micro-nano precision driving basic materials, piezoelectric ceramic materials and their application technology play a key role in the civil and defense fields. However, due to the intrinsic 6mm point group symmetry, the piezoelectric strain matrix of natural piezoelectric ceramics (describes the ability of piezoelectric materials to convert electric field into strain output; third-order tensor; with 18 matrix elements, ie pressure There are only five non-zero matrix elements in the electrical strain coefficient dij). For many years, almost all research has focused on how to synthesize new materials and how to improve five existing piezoelectric coefficients; although some scholars have begun to realize the existence of individual non-zero piezoelectric coefficient matrix elements, they have been lacking one. Theoretical research of the system. Therefore, in the field of piezoelectric science, every important progress is difficult, which limits the design and further development of piezoelectric devices.
New electromechanically coupled metamaterial design can produce all 18 piezoelectric coefficients that are non-zero
Recently, Science Advances, a journal of Science, reported Beijing in the form of Research Article-Physical Sciences with Designing electromechanical metamaterial with full nonzero piezoelectric coefficients (DOI:10.1126/sciadv.aax1782). The research and exploration of the university's Dong Xiaoxiang team in this field has made important progress.
Different from the traditional improvement of piezoelectric performance by doping-modified chemical methods, the research work is inspired by the principle of symmetry in condensed matter physics, and the design idea of ​​metamaterial ordered functional primitives is introduced into piezoelectric ceramic design, through delicate The new electromechanically coupled metamaterials obtained by topological and geometrical design have apparently broken the symmetry of piezoelectric ceramics intrinsic, and for the first time realized all non-zero 18 piezoelectric strain coefficient units, and some units have apparent piezoelectric coefficient measurements. It is more than an order of magnitude higher than the natural piezoelectric coefficient, breaking the traditional knowledge that the piezoelectric ceramic material has only five non-zero piezoelectric coefficients dij for more than 70 years, which brings a new design idea to the future development of piezoelectric devices. This work was evaluated by reviewers as "Will have a significant impact on various piezoelectric technologies". Symmetry breaking is the mechanism behind many physical phenomena (such as superconductivity and antiferromagnetic), but it is very difficult to construct a new controllable breaking symmetry from the microscopic. This work breaks the apparent symmetry through macroscopic element design. The idea of ​​achieving extraordinary physical parameters and performance enhancement is very instructive for creating new multi-field coupled metamaterials.
The ultra-material design apparently breaks the 6mm symmetry, resulting in a non-zero piezoelectric metamaterial with all 18 matrix elements.
The first author of the paper is Yang Jikun, a 2016 Ph.D. student at Peking University College of Engineering. Dong Xiaoxiang is the sole correspondent of the paper. Professor Wang Xiaohui and Academician Zhou Ji of Tsinghua University participated in the research of this subject; Academician Li Longtu of Tsinghua University gave support to this topic. The research was supported by the National Key Laboratory of Magnetic Functional Materials and Devices, funded by the National Natural Science Foundation of China (51772005, 51132001).