Abstract The dielectric properties of La0.7Sr0.25Na0.05Mn0.8Ti0.2O3 (LSNMTi0.2) were investigated as a function of temperature and frequency. Compared with the dielectric constants of most ferroelectric and relaxor materials, in this compound we have found a colossal dielectric constant phenomenon consisting in a low frequency dielectric constant e ″ over 106 around room temperature. However, Frequency and temperature dependent ac conductivity and complex impedance studies were linked to semiconducting grains and insulating grain boundaries, which support the non-Debye type of relaxation in the polycrystalline sample. Furthermore, decrease in the resistive properties with an increase in temperature, explained in terms of the mobility of the charge carriers, signaled the semi-conductor behavior with negative temperature coefficient of resistance (NTCR). The scaling behavior of the Modulus spectra M″ versus frequency allowed us to understand whether the short-range or the long-range movement of charge carriers is the dominant in relaxation process, confirming the non-Debye type of multiple relaxations in the system. The variation in the dielectric permittivity, explained in terms of the space charge polarization according to the Maxwell–Wagner model and the Koop's phenomenological theory and the large dielectric response, was induced by the barrier layers in the grain boundaries and the mixed-valent structures of Mn3+/Mn4+ and Ti4+/Ti3+.

中文翻译：

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La 0.7 Sr 0.25 Na 0.05 Mn 0.8 Ti 0.2 O 3 锰酸盐中的高介电常数和弛豫行为

摘要 研究了 La0.7Sr0.25Na0.05Mn0.8Ti0.2O3 (LSNMTi0.2) 的介电特性与温度和频率的关系。与大多数铁电材料和弛豫材料的介电常数相比，在这种化合物中，我们发现了一个巨大的介电常数现象，即室温附近的低频介电常数 e″超过 106。然而，频率和温度相关的交流电导率和复阻抗研究与半导体晶粒和绝缘晶界有关，这支持多晶样品中的非德拜型弛豫。此外，电阻特性随着温度的升高而降低，这可以用电荷载流子的迁移率来解释，用负电阻温度系数 (NTCR) 表示半导体行为。模量谱 M" 与频率的缩放行为使我们能够了解电荷载流子的短程或长程运动是弛豫过程中的主导因素，证实了系统中非德拜类型的多重弛豫。介电常数的变化，根据麦克斯韦-瓦格纳模型和库普现象学理论的空间电荷极化和大介电响应解释，是由晶界中的势垒层和混合价结构引起的Mn3+/Mn4+ 和 Ti4+/Ti3+。模量谱 M" 与频率的缩放行为使我们能够了解电荷载流子的短程或长程运动是弛豫过程中的主导因素，证实了系统中非德拜类型的多重弛豫。介电常数的变化，根据麦克斯韦-瓦格纳模型和库普现象学理论的空间电荷极化和大介电响应解释，是由晶界中的势垒层和混合价结构引起的Mn3+/Mn4+ 和 Ti4+/Ti3+。模量谱 M" 与频率的缩放行为使我们能够了解电荷载流子的短程或长程运动是弛豫过程中的主导因素，证实了系统中非德拜类型的多重弛豫。介电常数的变化，根据麦克斯韦-瓦格纳模型和库普现象学理论的空间电荷极化和大介电响应解释，是由晶界中的势垒层和混合价结构引起的Mn3+/Mn4+ 和 Ti4+/Ti3+。