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La1-xNdxB6块体材料。系统研究了La1-xNdxB6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La1-xNdxB6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, La0.1Nd0.9B6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La0.1Nd0.9B6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。
High purity and high density La1-xNdxB6 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 La1-xNdxB6 bulks were investigated systematically. The results show that high purity and high density La1-xNdxB6 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 La0.1Nd0.9B6 materials exhib-its 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 func-tion and improving the thermionic emission properties, the average of effective work function for La0.1Nd0.9B6 at dif-ferent temperatures is 2.72 eV.
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