低逸出功Ce_(1-x)Gd_xB_6单晶体的制备及其热发射性能  

Excellent Thermionic-emission Performances of(Ce_(1-x)Gd_x)B_6 with Ultra-low Work Functions

作　　者：王杨[1] 张忻[1] 张久兴[1,2] 刘洪亮[1] 江浩[1] 李录录 

机构地区：[1]北京工业大学材料科学与工程学院,新型功能材料教育部重点实验室,北京100124 [2]合肥工业大学材料科学与工程学院,合肥230009

出　　处：《无机材料学报》2016年第8期797-801,共5页Journal of Inorganic Materials

基　　金：国家自然科学基金(51371010);北京市教育委员会科技计划面上项目(KM201510005001)~~

摘　　要：以三元稀土硼化物Ce_(1-x)Gd_xB_6为研究对象,系统研究Gd掺杂对Ce B_6阴极材料热发射性能的影响规律。采用放电等离子烧结结合光学区域熔炼法成功制备了高质量的Ce_(1-x)Gd_xB_6(x=0~0.3)单晶体。借助360度Phi扫描单晶衍射仪对生长后的单晶进行了测试,结果显示单晶质量良好。采用劳埃定向仪确定出(100)晶面,并测试了该晶面在1673 K、1773 K、1873 K下的热电子发射电流密度。测试结果表明,Ce_(0.9)Gd_(0.1)B_6成分单晶体具有最优异的热发射性能,在1873 K工作温度下,4000 V电压条件下发射电流密度达到82.3 A/cm^2,零场电流发射密度为24.70 A/cm^2,平均有效逸出功为2.30 e V,与相同条件下Ce B_6单晶体热发射性能(热发射电流密度为78.2 A/cm^2,零场电流发射密度为13.32 A/cm^2)相比,其具有更大的发射电流密度和更低的逸出功。因此,采用该制备技术获得的Ce_(1-x)Gd_xB_6单晶体具有良好的发射性能,作为热阴极材料将会有更好的应用前景。Ce B_6 with simple cubic Ca B_6-type structure has attracted much interest owing to its promising scientific and technological characteristics like high brightness, high melting point, low vapor pressure, long service life, and low work function. High-quality Ce_（1-x）Gd_xB_6（x=0^0.3） single crystals with ultra-low work function are successfully synthesized via the spark plasma sintering combining floating zone technique. The quality, chemical composition and thermionic emission properties of the Ce_（1-x）Gd_xB_6 single crystals were systematically investigated by 360° phi scanning X-ray single crystal diffraction, X-ray fluorescence and emission measurements. Based on the testing results, the prepared single crystals exhibit good quality. The emission current density of Ce_（0.9）Gd_（0.1）B_6 on（100） crystal surface is up to 82.3 A/cm^2 higher than that of Ce B_6 under 4000 V at 1873 K, while the current density under zero voltage condition is 24.70 A/cm^2, about two-fold higher than that of Ce B_6. The average value of effective work functions at different temperatures is reduced to 2.30 e V lower than 2.93 e V of Ce B_6. Such excellent performances suggest that the ternary hexaborides can be used as a promising cathode emitter source for exploration and research in the electron emitter field.

关 键 词：光学区域熔炼法 Ce1-xGdxB6单晶体 热发射性能 

分 类 号：TQ174[化学工程—陶瓷工业]