Process Crystallographic Simulation for Biocompatible Piezoelectric Material Design and Generation

摘要

From 1880's discovery of piezoelectricity by French physicists Jacques and Pierre Curie, a huge number of piezoelectric materials have been developed and applied to the industrial equipment and scientific instrument. In the middle of 20th century, most widely used ceramic piezoelectric materials, BaTiO_3 (BTO) in 1944, PbTiO_3 in 1950, and Pb(Zr,Ti)O_3 (PZT) in 1955, were discovered through "hermetic art approach." It was not CAE driven material discovery. Actually, the experimental trial and error approach is inefficient way for the material discovery. Therefore a new CAE technique to develop a new high performance piezoelectric material under a short lead time is strongly required. It can analyze material characteristics, and design material structure and generation process simultaneously before actual production. This overall CAE technique for new material design and generation, which can be called as "process crystallographic simulation," is discussed in this state-of-the-art paper, which will be able to establish a new concept of material and process design. Now, we have serious problem with the piezoelectric material. Actually, PZT is most used in the world. However, "lead," which is a component of PZT-based piezoelectric material, is the toxic material. The usage of lead and toxic materials is prohibited by the waste electrical and electronic equipment (WEEE) and the restriction on hazardous substances (RoHS). Therefore, CAE driven new biocompatible material development is recognized as urgent subject. A goal is to develop an environmentally and biologically compatible piezoelectric material, which can be applied for human healthcare devices, such as Bio-MEMS devices. Until now, we have CAE methodologies to develop a new material, such as the atomic simulation, the continuum mechanics base finite element method, and the crystal process optimization method, but these are not cooperated effectively. An overall and simultaneous computational technique is strongly required. In this review paper, we survey and discuss numerical methodologies, "process crystallographic simulation," for material and generation process design. Further, an invention of a new biocompatible piezoelectric material, jts generation and validation of a newly developed numerical technique, are demonstrated. In this paper, below described subjects are reviewed and discussed. 1. Numerical analysis technique, "process crystallographic simulation," which consists of a three-scale structure analysis and a generation process analysis. 2. Material and Process design of new biocompatible piezoelectric materials. 3. Generation of MgSiO_3 thin film by using radio-frequency (RF) magnetron sputtering system. Validation of CAE technique. Consequently, a general concept of CAE driven material discovery technique could be understood through this state-of-the-art paper.