On the phase identity and its thermal evolution of lead free (Bi1/2Na1/2)TiO3-6 mol% BaTiO3
On the phase identity and its thermal evolution of lead free (Bi1/2Na1/2)TiO3-6 mol% BaTiO3
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DOI：
10.1063/1.3645054
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发表时间：
2011-10-01
影响因子：
3.2
通讯作者：
Roedel, Juergen
中科院分区：
文献类型：
--
作者：
Jo, Wook;Schaab, Silke;Roedel, Juergen
研究了0.94（Bi1/2Na1/2）TiO3 - 0.06BaTiO（3）（BNT-6BT）无铅压电陶瓷的介电常数随温度的变化规律，以解决该系统的晶体学和相稳定性问题。现有的现象学弛豫模型的应用，使整个介电常数谱的弛豫贡献被去卷积。与经典钙钛矿弛豫体，镧改性锆钛酸铅的温度相关的介电常数相比，去卷积的数据清楚地表明，BNT-6BT属于相同的弛豫体类别，这也证实了这两种材料的温度相关的极化磁滞回线的比较研究。基于这些结果，我们提出低温介电异常不涉及任何相变，如铁电反铁电。在室温下的透射电子显微镜和X射线衍射实验的支持下，我们提出，通常观察到的两个介电异常归因于R3c和P4bm对称性的铁电极性纳米区域的热演化，它们几乎在整个温度范围内共存，并随着温度可逆地相互转化。(C)2011年美国物理学会。[doi：10.1063/1.3645054]
Temperature-dependent dielectric permittivity of 0.94(Bi1/2Na1/2) TiO3-0.06BaTiO(3) (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-toantiferroelectric. 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3645054]