Analysis of polarization behavior in relaxation of BaTiO3-based ferroelectrics using wideband dielectric spectroscopy
Analysis of polarization behavior in relaxation of BaTiO3-based ferroelectrics using wideband dielectric spectroscopy
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DOI：
10.1109/tuffc.2010.1667
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发表时间：
2010-09
期刊：
影响因子：
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通讯作者：
T. Teranishi;T. Hoshina;H. Takeda;T. Tsurumi
中科院分区：
文献类型：
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作者：
T. Teranishi;T. Hoshina;H. Takeda;T. Tsurumi
讨论了BaTiO_3基铁电体从千赫到太赫兹的宽带介电谱。BaTiO_3(BT)、Ba0.6Sr0.4TiO_3(BST-0.6)和BaZr0.25Ti0.75O_3(BZT-0.25)陶瓷分别作为普通铁电材料、弥散相变铁电材料(DPT铁电材料)和弛豫铁电体材料。BT和BST-0.6陶瓷的离子极化随温度的变化可以用软声子模的软化来解释。在BZT0.25中，低频介电最高温度(Tm)处的介电常数异常不是由于软声子模的软化，而是由偶极极化(ε偶极)产生的介电常数。BZT0.25中的驰豫行为源于ε偶极子在TM上冷却时随频率增加而降低的幅度。在偶极极化方面，BT、BST0.6和BZT0.25在居里温度(TC)和Tm以上都表现出类似的ε偶极子的趋势。ε偶极子在T_c以下的行为可以用BT中的铁电畴来解释，而在T_m以下的ε偶极子的变化可以用BST0.6和BZT-0.25中的极性纳米区(PNR)的生长过程来解释。在这方面，BT可以与BST-0.6和BZT-0.25区分开来。BT中的弛豫可以解释为极化机制从正常铁电到弛豫铁电体通过DPT铁电体的连续变化。
Wideband dielectric spectra from the kilohertz to terahertz range are discussed for BaTiO3-based ferroelectrics. Ceramics of BaTiO3 (BT), Ba0.6Sr0.4TiO3 (BST-0.6), and BaZr0.25Ti0.75O3 (BZT-0.25) were selected as normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics), and relaxor ferroelectrics, respectively. The variation of ionic polarization in both BT and BST-0.6 ceramics with temperature could be explained by the softening of the soft phonon mode. In BZT-0.25, a permittivity anomaly at the dielectric maximum temperature (Tm) at low frequencies is not attributed to the softening of the soft phonon mode, but originates from the permittivity derived from the dipole polarization (εdipole). Relaxor behavior in BZT-0.25 is derived from the increase in the depression of εdipole on cooling across the Tm with increasing frequency. In dipole polarization, BT, BST- 0.6, and BZT-0.25 all exhibited a similar tendency of εdipole above the Curie temperature (Tc) and Tm. However, behavior of εdipole below the Tc can be explained by the ferroelectric domains in BT, whereas the variation of εdipole below the Tm could be explained by growth process of polar nanoregions (PNRs) in BST-0.6 and BZT-0.25. Regarding this, BT can be distinguished from BST-0.6 and BZT-0.25. Relaxation in BT could be interpreted as successive change in polarization mechanism from normal ferroelectrics to relaxor ferroelectrics via DPT ferroelectrics.