Abstract (Na0.5Bi0.5)0.94Ba0.06TiO3 + 0.3 wt.% Sm2O3 (named NBT-BT) lead-free piezoelectric ceramics were prepared by normal sintering. The effect of atmosphere sintering on NBT-BT ceramics was investigated through X-ray diffraction, dielectric, ferroelectric and piezoelectric characterizations. Real (Z′) and imaginary (Z″) parts of the complex impedance of the materials were also investigated. Dielectric studies exhibit a diffuse transition phase and are characterized by a temperature and frequency dispersion of permittivity, and this relaxation has been modeled using the modified Curie–Weiss law. The variation of the imaginary part (Z″) of impedance with frequency at various temperatures shows that the Z″ values reach a maxima peak (Z″max). The appearance of single semicircle in the Nyquist plots (Z″ vs Z′) pattern at high temperatures suggests that the electrical process occurring in the material has a relaxation process possibly due to the contribution of bulk material only. It shows that the compound exhibit negative temperature coefficient of resistance (NTCR) type behavior usually found in semiconductors. The bulk resistance of the material decreases with rising temperatures similar to a semiconductor, and the Nyquist plot showed the negative temperature coefficient of resistance (NTCR) character of materials. Also, the frequency-dependent AC conductivity at different temperatures indicated that the conduction process is thermally activated process. The plots of the relaxation times τZ″ and τM″ as a function of temperature follow the Arrhenius law, where a single slope is observed with activation energy values come to near 1.70.

中文翻译：

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(Na0.5Bi0.5)0.94Ba0.06TiO3 + 0.3wt.% Sm2O3无铅陶瓷在不同条件下烧结的阻抗谱分析及压电性能

摘要 采用普通烧结法制备了(Na0.5Bi0.5)0.94Ba0.06TiO3 + 0.3 wt.% Sm2O3（命名为NBT-BT）无铅压电陶瓷。通过 X 射线衍射、介电、铁电和压电特性研究了气氛烧结对 NBT-BT 陶瓷的影响。还研究了材料复阻抗的实部（Z'）和虚部（Z”）。介电研究表现出扩散转变阶段，其特征在于介电常数的温度和频率色散，并且这种弛豫已使用修改后的居里 - 魏斯定律建模。阻抗的虚部 (Z") 在不同温度下随频率的变化表明 Z" 值达到最大峰值 (Z"max)。高温下 Nyquist 图中出现的单个半圆（Z″ vs Z′）表明材料中发生的电过程具有弛豫过程，这可能仅仅是由于块状材料的贡献。它表明该化合物表现出通常在半导体中发现的负电阻温度系数 (NTCR) 型行为。与半导体类似，材料的体电阻随温度升高而降低，奈奎斯特图显示材料的负电阻温度系数 (NTCR) 特性。此外，不同温度下的频率相关交流电导率表明传导过程是热激活过程。弛豫时间 τZ" 和 τM" 作为温度函数的图遵循阿伦尼乌斯定律，