Temperature-field phase diagrams near the morphotropic phase boundary in perovskite-type ferroelectrics

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400323
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Iwata Makoto 名古屋工業大学, 工学(系)研究科(研究院), 教授 (40262886)
• Co-Investigator(Kenkyū-buntansha): MAEDA MASAKI 名古屋工業大学, 大学院工学研究科, 教授 (10091745)
• Research Collaborator: ISHIBASHI YOSHIHIRO 名古屋大学, 名誉教授 ; ANDO KENICHIROU 名古屋工業大学, 大学院工学研究科, 大学院生 ; YOKOI RYUTA 名古屋工業大学, 大学院工学研究科, 大学院生 ; SUGIYAMA YUTA 名古屋工業大学, 大学院工学研究科, 大学院生 ; NAGAHASHI RYO 名古屋工業大学, 大学院工学研究科, 大学院生
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 強誘電体 / 電場誘起相転移 / 構造相転移 / モルフォトロピック相境界 / 電場相図 / 臨界点 / ペロブスカイト / 誘電率

Outline of Final Research Achievements

The purpose of our study is to clarify responses of the polarization under the electric field near the morphotropic phase boundary in the perovskite-type ferroelectric Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) mixed crystal system. In the present study, we experimentally clarified the temperature-concentration-field phase diagram in PZN-PT. It was found that on the phase diagram, the critical endpoint exists under the electric field along the [001]-direction, and the stable orthorhombic phase exists under zero field. The Curie-Weiss constant in PZN-8%PT can be determined by using our results of the dielectric constant in the high temperature range and T0 obtained from the temperature-field phase diagram. Furthermore, it was clarified that the reason why the third-order dielectric susceptibility takes positive value in the paraelectric phase is that the phase transition under zero field is of the first-order.

Free Research Field

物性 I