Abstract SrTi1−3x(CuxNb2x)O3 (x = 0.05, 0.1, 0.15 and 0.2) ceramics were synthesized using a solid-state reaction method at 1400 °C in air. Their structures, valence states, conduction mechanisms and dielectric properties were investigated in detail. Fine grains and vibration modes of the samples related to the doping effects were observed. A distorted pseudo-cubic structure was confirmed by XRD and Raman spectroscopy. All ceramics exhibited a colossal dielectric constant and dielectric relaxations. The dielectric constant in the low- and high-frequency ranges for x = 0.05 and 0.1 was ascribed to the contribution of the grain boundary and grain, respectively, and the electrode polarization was significant at x = 0.15 and 0.2. The dielectric relaxation peaks obeyed the T−1/4 law at low temperature for all samples, confirming the polaron relaxation process. The electric modulus analysis confirmed that low-temperature dielectric relaxation was related to the grain response, and the electric conduction exhibited the same behavior with the dielectric relaxation. The variable-range-hopping conduction indicated a highly distorted structure and the localization of carriers in SrTi1−3x(CuxNb2x)O3, which was consistent with the XRD and Raman results. The mixed-valence structure of Cu was identified by XPS, and the polaron hopping between the mixed-valence Cu ions was supposed to be responsible for the dielectric relaxation and electric conduction.

中文翻译：

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Cu和Nb共掺杂细晶SrTiO3陶瓷的介电弛豫

摘要 SrTi1−3x(CuxNb2x)O3 (x = 0.05, 0.1, 0.15 and 0.2) 陶瓷是在空气中 1400 °C 下采用固相反应法合成的。详细研究了它们的结构、价态、导电机制和介电性能。观察到与掺杂效应相关的样品的细晶粒和振动模式。XRD 和拉曼光谱证实了扭曲的假立方结构。所有陶瓷都表现出巨大的介电常数和介电弛豫。x = 0.05 和 0.1 的低频和高频范围内的介电常数分别归因于晶界和晶粒的贡献，电极极化在 x = 0.15 和 0.2 处显着。所有样品的介电弛豫峰在低温下均遵循 T−1/4 定律，确认极化子弛豫过程。电模量分析证​​实低温介电弛豫与晶粒响应有关，导电表现出与介电弛豫相同的行为。可变距离跳跃传导表明 SrTi1−3x(CuxNb2x)O3 中的载流子结构高度扭曲，定位与 XRD 和拉曼结果一致。通过XPS鉴定了Cu的混合价结构，混合价Cu离子之间的极化子跳跃被认为是介电弛豫和导电的原因。可变距离跳跃传导表明 SrTi1−3x(CuxNb2x)O3 中的载流子结构高度扭曲，定位与 XRD 和拉曼结果一致。通过XPS鉴定了Cu的混合价结构，混合价Cu离子之间的极化子跳跃被认为是介电弛豫和导电的原因。可变距离跳跃传导表明 SrTi1−3x(CuxNb2x)O3 中的载流子结构高度扭曲，定位与 XRD 和拉曼结果一致。通过XPS鉴定了Cu的混合价结构，混合价Cu离子之间的极化子跳跃被认为是介电弛豫和导电的原因。