Enhanced thermionic electron emission of (La1-x-yPrxBay)B6 cathode transforming from the grain boundary to the grain

IF 3.5 3区材料科学 Q1 MATERIALS SCIENCE, CERAMICS

Journal of the American Ceramic Society Pub Date : 2025-01-15 DOI:10.1111/jace.20373

Xinyu Yang, Yulin Song, Zimeng Li, Biao Cai, Cunchao Dong, Chenhui Deng, Yan Wang, Jianing Zhang, Wenpeng Xiang, Jiuxing Zhang

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引用次数: 0

Abstract

The mixed rare earth/alkali earth was initially employed to enhance the thermionic emission performance of lanthanum hexaboride (LaB₆) through forming the high-dense (La_1-x-yPr_xBa_y)B₆ polycrystal by spark plasma sintering (SPS). La_0.6Pr_0.3Ba_0.1B₆ exhibits the highest current density in space charge limited (SCL) region at T = 1873K while La_0.5Ba_0.5B₆ has the highest current density in temperature limited (TL) region. The maximum current density of 14.07 A/cm² at T = 1673K for La_0.5Ba_0.5B₆ is higher than that of 11.71 A/cm² at T = 1873K for LaB₆ polycrystal, presenting superior emission characteristics at the low temperature, mainly ascribed to the contribution of the Ba element. With the increase in the Ba content, the location of the highest electron emission shifts from the grain boundary (in La_0.5Pr_0.5B₆ and La_0.6Pr_0.3Ba_0.1B₆) to the internal grain (in La_0.6Pr_0.1Ba_0.3B₆ and La_0.5Ba_0.5B₆). The consumption rate of the elements during thermionic emission follows the order: Ba > Pr > La. The experimental data on the current density aligns closely with the theoretical predictions, demonstrating the emission of (La_1-x-yPr_xBa_y)B₆ ceramic obeys classical thermionic emission mechanism of metals.

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通过火花等离子烧结（SPS）形成高密度（La1-x-yPrxBay）B6 多晶体，最初采用稀土/碱土混合物来提高六硼化铋镧（LaB6）的热离子发射性能。在 T = 1873K 时，La0.6Pr0.3Ba0.1B6 在空间电荷受限（SCL）区域显示出最高的电流密度，而 La0.5Ba0.5B6 在温度受限（TL）区域显示出最高的电流密度。在 T = 1673K 时，La0.5Ba0.5B6 的最大电流密度为 14.07 A/cm2，高于 LaB6 多晶在 T = 1873K 时的 11.71 A/cm2，在低温下呈现出更优越的发射特性，这主要归功于 Ba 元素的贡献。随着钡元素含量的增加，电子发射率最高的位置从晶界（La0.5Pr0.5B6 和 La0.6Pr0.3Ba0.1B6）转移到晶粒内部（La0.6Pr0.1Ba0.3B6 和 La0.5Ba0.5B6）。在热电子发射过程中，元素的消耗率按照以下顺序进行： Ba > Pr > La。电流密度的实验数据与理论预测结果非常吻合，证明 (La1-x-yPrxBay)B6 陶瓷的发射符合经典的金属热离子发射机制。

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来源期刊

Journal of the American Ceramic Society 工程技术-材料科学：硅酸盐

CiteScore

7.50

自引率

7.70%

发文量

590

审稿时长

2.1 months

期刊介绍： The Journal of the American Ceramic Society contains records of original research that provide insight into or describe the science of ceramic and glass materials and composites based on ceramics and glasses. These papers include reports on discovery, characterization, and analysis of new inorganic, non-metallic materials; synthesis methods; phase relationships; processing approaches; microstructure-property relationships; and functionalities. Of great interest are works that support understanding founded on fundamental principles using experimental, theoretical, or computational methods or combinations of those approaches. All the published papers must be of enduring value and relevant to the science of ceramics and glasses or composites based on those materials. Papers on fundamental ceramic and glass science are welcome including those in the following areas: Enabling materials for grand challenges[...] Materials design, selection, synthesis and processing methods[...] Characterization of compositions, structures, defects, and properties along with new methods [...] Mechanisms, Theory, Modeling, and Simulation[...] JACerS accepts submissions of full-length Articles reporting original research, in-depth Feature Articles, Reviews of the state-of-the-art with compelling analysis, and Rapid Communications which are short papers with sufficient novelty or impact to justify swift publication.