材料科学
电介质
铁电性
锆钛酸铅
介电常数
反铁电性
相变
凝聚态物理
磁滞
大气温度范围
钙钛矿(结构)
铁电陶瓷
相(物质)
矿物学
热力学
结晶学
化学
光电子学
物理
有机化学
作者
Wook Jo,Silke Schaab,Eva Sapper,Ljubomira Ana Schmitt,Hans‐Joachim Kleebe,Andrew J. Bell,Jürgen Rödel
摘要
Temperature-dependent dielectric permittivity of 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3 (BNT-6BT) lead-free piezoceramics was studied to disentangle the existing unclear issues over the crystallographic aspects and phase stability of the system. Application of existing phenomenological relaxor models enabled the relaxor contribution to the entire dielectric permittivity spectra to be deconvoluted. The deconvoluted data in comparison with the temperature-dependent dielectric permittivity of a classical perovskite relaxor, La-modified lead zirconate titanate, clearly suggest that BNT-6BT belongs to the same relaxor category, which was also confirmed by a comparative study on the temperature- dependent polarization hysteresis loops of both materials. Based on these results, we propose that the low-temperature dielectric anomaly does not involve any phase transition such as ferroelectric- to-antiferroelectric. Supported by transmission electron microscopy and X-ray diffraction experiments at ambient temperature, we propose that the commonly observed two dielectric anomalies are attributed to thermal evolution of ferroelectric polar nanoregions of R3c and P4bm symmetry, which coexist nearly throughout the entire temperature range and reversibly transform into each other with temperature.
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