With the increasing demand of high-power and pulsed power electronic devices, environmental-friendly potassium sodium niobate ((Na0.5K0.5)NbO₃, KNN) ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density (Wrec). Nevertheless, the dielectric loss also increases as the external electric field increases, which will generate much dissipated energy and raise the temperature of ceramic capacitors. Thus, an effective strategy is proposed to enhance the energy storage efficiency (η) via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na0.5K0.5)-NbO₃–0.1Bi(Zn2/3(NbxTa1−x)1/3)O₃ ceramics. On the one hand, the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short–range polar nanoregions (PNRs), resulting in the highη. On the other hand, the introduction of Ta ions could boost the intrinsic band energy gap and thus improve theEb. As a result, highWrec of 3.29 J/cm³ and ultrahighη of 90.1% at the high external electric field of 310 kV/cm are achieved inx = 0.5 sample. These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.With the increasing demand of high-power and pulsed power electronic devices, environmental-friendly potassium sodium niobate ((Na0.5K0.5)NbO₃, KNN) ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density (Wrec). Nevertheless, the dielectric loss also increases as the external electric field increases, which will generate much dissipated energy and raise the temperature of ceramic capacitors. Thus, an effective strategy is proposed to enhance the energy storage efficiency (η) via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na0.5K0.5)-NbO₃–0.1Bi(Zn2/3(NbxTa1−x)1/3)O₃ ceramics. On the one hand, the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short–range polar nanoregions (PNRs), resulting in the highη. On the other hand, the introduction of Ta ions could boost the intrinsic band energy gap and thus improve theEb. As a result, highWrec of 3.29 J/cm³ and ultrahighη of 90.1% at the high external electric field of 310 kV/cm are achieved inx = 0.5 sample. These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.

本文采用传统固相反应法, 成功制备了新型无铅弛豫铁电陶瓷(1-x)［0.9BaTiO3-0.1Bi(Mg0.25Ta0.5)O3］-xBi0.5Na0.5TiO3。结果表明, 较高居里温度的Bi0.5Na0.5TiO3的引入, 使得材料体系中建立了更多的以Bi-O耦合为主的极性纳米区域, 弥补了因Bi(Mg0.25Ta0.5)O3的加入导致的宏观极化强度的减少, 提高了材料的饱和极化强度, 实现了较高储能密度的同时具有更好的温度稳定性。在245 kV/cm电场强度下, x=0.2样品的储能密度约为4.01 J/cm3, 储能效率约为84.86%, 同时该组分在20~170 ℃储能密度的变化率小于5%, 储能效率的变化率小于6%, 表现出优异的温度稳定性。

按照激光放大器能量传输和转化过程, 利用激光速率方程和氙灯辐射方程、光线追迹软件等理论方法和分析计算工具, 对氙灯泵浦钕玻璃激光放大器进行储能效率和能量转换环节的理论分析以及定量、半定量计算, 系统分析各种能量转化与损耗因素对放大器储能效率的影响。理论研究的成果与放大器实验考核的结果相一致。

给出了髙功率钕玻璃固体激光放大器小信号增益特性的时间和光谱分辨的物理模型,该模型包括了激光放大器能量转换的4个主要环节:抽运源、腔传输、增益介质、增益特性与储能效率。该模型详细地考虑了氙灯辐射 的光谱和时间特性, 以及增益介质中钕离子的光谱吸收特性。利用该物理模型,对目前正在研制的口径为300 mm×300 mm高功率钕玻璃固体激光放大器的各单元参数进行了细致的优化,并给出了放大器的增益特性及储能效 率, 模拟计算结果表明, 在23 kV常规工作电压下,放大器小信号增益系数为5.0% cm-1,储能效率为3.0%,满足设计要求。

利用俄罗斯2×1×3组合式片状放大器对国产N31新型磷酸盐激光玻璃和俄罗斯激光玻璃的增益特性进行了对比性实验研究,在相同的抽运条件下,得到了国产N31新型磷酸盐激光玻璃增益能力比俄罗斯激光玻璃高83.4%的实验结果.