悬浮区域熔炼法制备LaB_6单晶体与发射性能研究  

Floating zone growth and emission properties of single crystal LaB_6 cathode

作　　者：包黎红[1] 张久兴[1] 周身林[1] 张宁[1] 

机构地区：[1]北京工业大学材料学院新型功能材料教育部重点实验室,北京100124

出　　处：《物理学报》2011年第10期517-523,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50871002)资助的课题~~

摘　　要：采用区域熔炼法成功制备出了高质量,高纯度,大尺寸的LaB6单晶体.系统分析了制备过程中每个参数对LaB6单晶生长的影响,确定了晶体生长最佳工艺为:样品转速为30r/min,生长速度为8—10mm/h.分析了单晶LaB6(100)晶面的热电子发射性能,结果表明,当阴极温度为1873K时,最大热发射电流密度为44.36A/cm2;利用Richardson直线法求出了绝对零度逸出功和有效逸出功分别为1.99和2.59eV.场发射测试结果表明,单晶LaB6场发射单尖最大场发射电流密度达到4.9×106A/cm2,场发射因子为41500cm-1,表现出良好的场发射性能.因此单晶LaB6作为热阴极和冷阴极都具有很广阔的应用前景.The high quality,high purity and large size Lanthanum hexaborides（LaB6） single crystals have been successfully grown by optical floating zone method.The optimum crystal growth parameters are listed as follow：sample rotation rate is 30 r/min and the growth rate is 8—10 mm/h.The largest thermionic emission current density of（100） crystal surface is 44.36 A/cm2 at 1873 K.The work function at absolute zero is calculated to be 1.99 eV by Richardson line method,and the average value of effective work functions at different temperatures are calculated to be 2.59 eV.The field emission characteristic of single crystal LaB6 field emitting single tip show that the maximum field emission current density is 4.9×106 Acm-2 and the field enhancement factor is calculated to be 41500 cm-1,indicating excellent field emission performance.Thus,the single crystal is a promising cathode material for practical applications regarding to its excellent thermionic emission or field emission properties.

关 键 词：区域熔炼法 单晶LaB6 热发射性能 场发射性能 

分 类 号：O614.331[理学—无机化学]