用于能量储存的介电铁电材料具有高可靠性和高充放电速率等特点，在高新技术领域中具有重要应用。近年来具有双电滞回线特征的反铁电储能材料已成为研究热点。AgNbO₃是一种新型无铅反铁电陶瓷材料，具有高饱和极化、低剩余极化，在能源储存系统和大功率电子设备领域显示巨大潜力。但是AgNbO₃陶瓷电容器在室温及以上工作温域内介电性能不稳定，储能密度和储能效率较低，限制其进一步应用在储能器件领域。本论文以传统固相反应法制备了离子掺杂型AgNbO₃陶瓷，结合物相结构和电子能带结构信息，探索离子掺杂对AgNbO₃陶瓷电学性能的影响，并系统研究了AgNbO₃陶瓷的介电稳定性及储能特性。
         首先，采用固相反应法制备了Ag_1-3xBi_xNbO₃ (x=0～0.03)陶瓷材料，随掺杂含量增大，晶胞体积增大，晶粒尺寸减小。基于第一性原理计算Bi³⁺掺杂AgNbO₃的电子能带结构、电子态密度和介电函数，探索电子轨道杂化与AgNbO₃铁电性的关系。结果表明Bi³⁺掺杂使禁带宽度从1.740 eV降低到1.523 eV，费米能级附近电子轨道杂化增强。在x=0.03时，25～278 ℃温度范围内TCC(25 °C)≤±15%，具有良好的宽温域介电稳定性。
          其次，制备了Zn²⁺、Sc³⁺和Ti⁴⁺掺杂AgNbO₃陶瓷材料，并通过计算B位掺杂AgNbO₃的电子能带结构和介电函数，结合电子轨道杂化分析B位离子掺杂对电性能的影响。结果表明Sc³⁺掺杂AgNbO₃陶瓷，晶粒尺寸明显降低，介电峰向低温方向移动，介电温度稳定性和室温介电常数提高。
         基于A、B位单掺杂结果，制备了A、B位离子共掺杂型Ag_1-3x Bi_xNb_1-3/5xSc_xO₃ (x=0～0.03)陶瓷，结果表明掺杂导致晶胞体积膨胀，晶粒尺寸减小，掺杂产生的点缺陷与容忍因子的降低增强了反铁电性。当电场强度为200 kV/cm时，陶瓷电容的可恢复储能密度在x=0.01处达到3.31 J/cm³，储能效率在x=0.02处达到70.11%。此外，当x=0.03，陶瓷在25 °C到300 °C范围内介电性能具有良好稳定性。
 

        Dielectric and ferroelectric materials are promising candidate used for energy storage because of the high reliability and high charge and discharge rate. They have important applications in the field of new and high technology. In recent years, anti-ferroelectric energy storage materials with double hysteresis loops have become a research hotspot. AgNbO₃ is a new type lead-free anti-ferroelectric ceramic material with high saturation polarization and low remnant polarization, and shows great potential in energy storage systems and high-power electronic devices. However, the dielectric properties in the operating temperature above room temperature of AgNbO₃ ceramic capacitors are unstable, which result in low energy storage density and efficiency, and limit their further application in the field of energy storage devices. The traditional solid-state reaction method was used to prepare ion-doped AgNbO₃ ceramics in this work. Combining the information of phase structure and electronic band structure, the influence of ion doping on the electrical properties of AgNbO₃ ceramics was explored, the stability of dielectric properties and energy storage properties of AgNbO₃ ceramics were systematically studied.
Firstly, Ag_1-3x Bi_xNbO₃ (x=0～0.03) ceramics were fabricated through solid-state reaction method. The average grain size decreased while the cell volume increased with doping content. The effects of Bi³⁺ doped AgNbO₃ ceramics were studied by the first principles calculation. The band structure, the density of states, the dielectric function, and the relation between the ferroelectricity and orbital hybridization were explored. The results demonstrate that the band gap reduced from 1.740 eV to 1.523 eV, and the orbital hybridization of electron orbitals near the Fermi energy level was enhanced. When x=0.03, the ceramic exhibit good dielectric thermal stability between 25 °C and 278 °C with a TCC(25 °C) value of less than ±15%.
Secondly, the Zn²⁺, Sc³⁺ and Ti⁴⁺ was doped into the B-site of AgNbO₃ ceramics. The band structure and dielectric function of B-site doping AgNbO₃ ceramics were calculated, and the effects of B-site ion doping on the electrical properties were studied by combining the hybridization of electron orbitals. The results show that the grain size of AgNbO₃ ceramics doping with Sc³⁺ decreased obviously, and the dielectric anomalies moved towards low temperature, which enhance the dielectric thermal stability and improve the dielectric constant at room temperature.
Based on the above results of separate doping of the A-site and B-site, Bi³⁺ and Sc³⁺co-doped AgNbO₃ ceramics were fabricated according to the formula of Ag_1-3x Bi_xNb_1-3/5xSc_xO₃ (x = 0～0.03). The results show that doping leads to the expansion of cell volume and reduction of grain size. The anti-ferroelectricity was enhanced due to the production of point defects and reduction of the tolerance factor. When the electric field increase to 200 kV/cm, the ceramic obtained a high energy storage density of 3.31 J/cm³ at x=0.01, and the energy storage efficiency of 70.11% was achieved at x=0.02. Moreover, the ceramic at x=0.03 shows excellent dielectric thermal stability from the temperature range of 25～300 °C.
 

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