La1-xNdxB6阴极材料的制备及性能研究

以高纯金属La块、Nd块和B粉为原料, 通过蒸发-冷凝与放电等离子烧结(SPS)结合的技术成功制备了高纯高致密的多元稀土六硼化物La_1-xNd_xB₆块体材料。系统研究了La_1-xNd_xB₆材料的物相组成、力学性能、电阻率及热电子发射性能。结果表明, 采用上述工艺制备了高纯高致密的La_1-xNd_xB₆单相块体材料。烧结样品的维氏硬度和抗弯强度可达26.70 GPa和230.48 MPa。热电子发射性能测试结果表明, La_0.1Nd_0.9B₆成分块体具有最佳的热发射性能, 在1600℃, 4 kV外加电压条件下, 发射电流密度达到32.04 A/cm², 零场电流密度达到12.72 A/cm², 在同样条件下优于纯LaB₆和NdB₆块体材料的热发射性能。计算得到La_0.1Nd_0.9B₆在不同温度下的平均有效逸出功为2.72 eV, 表明适当比例的复合可以降低逸出功, 提高热电子发射性能。

Preparation and Property of La1-xNdxB6 Cathode Material

High purity and high density La_1-xNd_xB₆ bulks were prepared by using evaporation condensation combined spark plasma sintering (SPS) with high-purity metal La, Nd bulks and B powder as raw materials. Phase component, the mechanical properties, the resistivity and the thermionic emission properties of La_1-xNd_xB₆ bulks were investigated systematically. The results show that high purity and high density La_1-xNd_xB₆ single-phase bulk material can be prepared by using the above mentioned technology. The sintered samples show high value of Vickers hardness (26.70 GPa) and bending strength (230.48 MPa). According to the thermionic emission results, the bulk of La_0.1Nd_0.9B₆ materials exhibits optimum thermal emission properties, the emission current density is 32.04 A/cm² and zero field current density reaches 12.72 A/cm² at the temperature of 1600℃ and the applied voltage of 4 kV, which is better than LaB₆ and NdB₆ bulk samples under the same conditions. It is shown that proper Nd content is benefit to reducing the work function and improving the thermionic emission properties, the average of effective work function for La_0.1Nd_0.9B₆ at different temperatures is 2.72 eV.