放电等离子烧结原位合成LaxCe1-xB6化合物及性能研究

以LaH₂, CeH₂纳米粉和无定形B粉为原料, 通过放电等离子烧结原位合成法制备了单相、高致密度的La_xCe_1-xB₆稀土六硼化物. 系统研究了该系列化合物的晶体结构、表面织构、力学性能、电输运特性及热发射性能. 结果表明, 该方法制备出的样品致密度均高于96%, 维氏硬度最高值达到2310 kg/mm², 说明具有良好的力学性能. 热发射结果表明, 当阴极温度为1873 K, 外加电压为1 kV时, La_0.6Ce_0.4B₆的最大发射电流密度达到40.7 A/cm², 该值高于单纯LaB₆和CeB₆电流密度值. 因此, La_xCe_1-xB₆多元稀土六硼化物作为热阴极材料将有良好的应用前景. 关键词： 稀土六硼化物 阴极材料 热电子发射

Synthesis and properties of Lax Ce1-x B6 compounds by in-situ spark plasma sintering

Polycrystalline rare-earth hexaboride (La_xCe_1-x)B₆ were prepared by means of the reactive spark plasma sintering (SPS), using mixed powders of GdH₂, NdH₂ and B. The crystal structure, surface texture, mechanical property, electrical resistivity, and thermionic emission properties of the sintered samples were investigated. It is found that all the samples sintered by SPS exhibit high densily (>96%) and high value of Vickers hardness (2310 kg/mm²), which are much higher than those made by traditional method. Thermionic emission results indicate that the maximum emission current density of La_0.6Ce_0.4B₆ is 40.7 A/cm² under the applied voltage of 1 kV at 1873 K, which is larger than that of LaB₆ and CeB₆. Thus, the mixed cystal of borides (La_xCe_1-x)B₆, as a cathode, promises good prospects in application.
Keywords： rare-earth hexaboride cathode materials thermionic emission