Creation of dielectric materials for high-temperature capacitor applications using relaxor phases of A-site complex perovskites

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K18241
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Inorganic materials/Physical properties
• Research Institution: Keio University
• Principal Investigator: Hagiwara Manabu 慶應義塾大学, 理工学部(矢上), 助教 (30706750)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 誘電体 / セラミックス / リラクサー / 水熱法 / Aサイト複合ペロブスカイト / 高温

Outline of Final Research Achievements

This study aimed to develop high-temperature dielectric materials using the relaxor phase of bismuth potassium titanate (BKT). We first studied the mechanism underlying the spontaneous relaxor-ferroelectric phase transition of BKT through analyses of dielectric responses of high-quality ceramic samples fabricated via a hydrothermal process. We found that the transition was triggered by freezing of the thermal fluctuation of polar nanoregions existing in the relaxor phase. We also measured the dielectric responses of BKT under biasing electric field and uniaxial load. Based on these results, electric field-temperature and stress-temperature phase diagrams are firstly determined for BKT. We then fabricated solid solutions between BKT and strontium titanate (ST), (1-x)BKT-xST, to shift the dielectric maximum temperature of BKT toward room temperature. Consequently, 0.5BKT-0.5ST ceramics showed high dielectric permittivity exceeding 1000 in a wide temperature range up to 300°C.

Free Research Field

無機材料化学