采用反应放电等离子烧结技术, 以BaH2, GdH2纳米粉和B粉为原料, 成功制备了多晶稀土硼化物(BaxGd1-x)B6 (x=0, 0.2, 0.4, 0.8). 采用XRD、EBSD技术研究了掺杂元素Ba对GdB6晶体结构及晶粒取向的影响, 并测量不同温度下的热发射性能. 结果表明, 所有烧结样品与传统烧结方法相比, 具有高致密度(>97%)和很高的维氏硬度(2070 kg/mm2). GdB6 在1873 K时, 最大发射电流密度为11 A/cm2, 该值远高于传统方法制备的电流密度值. 随着Ba含量的增加, 发射电流密度从11 A/cm2 减小到2.25 A/cm2.
The polycrystalline rare-earth hexaborides (BaxGd1-x)B6 (x = 0, 0.2, 0.4, 0.8) were prepared by the reactive spark plasma sintering (SPS) method using mixed powder of BaH2, GdH2 and B. The effects of Ba doping content on the crystal structure, the grain orientation and the thermionic emission properties of the GdB6 were investigated by X-ray diffraction, electron backscattered diffraction and emission current measurements. It is found that all the sintered samples exhibit high densification (> 97%) and high value of Vickers hardness (2070 kg/mm2). The maximum thermionic emission current density of GdB6 is 11 A/cm2 at a cathode temperature of 1873 K, which is much higher than that of traditional method. With the increase of Ba content, the thermionic emission current density decreases from 11 A/cm2 to 2.25 A/cm2 at 1873 K.
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