中文摘要：

以CeB6和PrB6粉末为原料,采用放电等离子烧结结合悬浮区域熔炼法成功制备了晶体质量良好的多元稀土六硼化物Ce1-xPrxB6（x=0.1、0.2、0.4）单晶体,并系统研究了该系列单晶体（100）晶面热电子发射性能。结果表明：Ce0.8Pr0.2B6单晶（100）晶面具有最好的热发射性能,在1873 K,最大电流发射密度达到66.07 A/cm^2,比CeB6单晶的电流发射密度提高约20%。此外,Ce0.9Pr0.1B6、Ce0.6Pr0.4B6单晶（100）晶面的热发射电流密度分别为65.81 A/cm^2和65.31 A/cm^2。Ce0.8Pr0.2B6单晶（100）晶面的逸出功最低,为2.61 eV,其它单晶（100）晶面的逸出功在2.64～2.753 eV范围内。因此,Ce1-xPrxB6多元稀土六硼化物单晶具有良好的发射性能和低的逸出功,作为热阴极材料有很好的应用前景。

英文摘要：

High-quality single crystals Ce1-xPrxB6（x = 0.1, 0.2, 0.4） hexaborides were successfully prepared by the reactive spark plasma sintering（SPS） combining with the floating zone melting method using powder of CeB6 and PrB6 as raw materials. The thermionic emission properties of the（100） plane of single crystals were investigated. Results show that the（100） plane of Ce0.8Pr0.2B6 single crystal has the maximum emission current density, 66.07 A/cm^2 at 1873 K, which is higher than the current reported CeB6 single crystal, increased by about 20%. In addition, the thermal emission current density of（100） plane of Ce0.9Pr0.1B6, Ce0.6Pr0.4B6 single crystals are 65.81 A/cm^2 and 65.31 A/cm^2, respectively. The（100） plane of Ce0.8Pr0.2B6 single crystal has the lowest work function of 2.61 eV, while the work functions of other single crystals are in the range of 2.64-2.753 eV. Therefore, single crystals Ce1-xPrxB6 hexaborides have good thermionic emission and low work function, which promises good prospects in the application as a hot cathode material.