Neutron diffraction study of field-cooling effects on the relaxor ferroelectric Pb[(ZnNb)Ti]O

中性子回折によるリラクサー強誘電体Pb[(ZnNb)Ti]Oの電場中冷却効果の研究

大和田 謙二; 廣田 和馬*; Rehrig, P. W.*; 藤井 保彦*; 白根 元*

Owada, Kenji; Hirota, Kazuma*; Rehrig, P. W.*; Fujii, Yasuhiko*; Shirane, Gen*

高電場-高温度のもと、中性子回折実験を注意深く行った結果、PZN-8%PTの分極回転の経路に関する詳細な温度電場相図を完成させた。これによりPZN-8%PTの温度-電場経歴依存性が明らかになった。さらにゼロ電場中冷却で今まで菱面体相と考えられてきた相が、実はもっと対称性の低い相であることがわかった。われわれはこの相をX相と名づけた。

High-temperature () and high-electric-field () effects on Pb[(ZnNb)Ti]O (PZN-8%PT) were studied comprehensively by neutron diffraction in the ranges ~K and ~kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field cooling process (FC, ~kV/cm), a successive cubic (C) tetragonal (T) monoclinic (M) transition was observed. In the zero field cooling process (ZFC), however, we have found that the system does transform to the rhombohedral (R) phase as widely believed, but to a new, unidentified phase, which we call X. X gives a Bragg peak profile similar to that expected for R, but the -axis is always slightly shorter than the -axis. As for field effects on the X phase, it transforms into the M phase via another monoclinic phase (M) as expected from a previous report [Noheda , 224101 (2002)].