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采用X射线劳厄定向法对单晶CeB6的（110），（111），（210）和（310）晶面进行了定向.系统研究了不同晶面热发射性能及磁场对电阻率的影响规律.结果表明，当阴极温度为1873 K时（110），（111），（210）和（310）晶面最大发射电流密度分别为38.4，11.54，50.4和20.8 A/cm2，表现出了发射性能的“各向异性”.Richardson-Dushman公式计算逸出功结果表明，上述晶面中（210）晶面具有最低的逸出功，为2.4 eV.从实际应用来看，该晶面有望替代商业化的钨灯丝成为新一代的场发射阴极材料.磁电阻率测量结果显示，当晶体从[001]方向旋转至[011]方向时电阻率从73 μupΩ·cm变化至69 μupΩ·cm，表明电阻率在磁场中沿不同方向同样具有“各向异性”的特点.Cerium hexaboride (CeB6) as a heavy fermion compound displays a number of interesting low-temperature physical properties such as dense Kondo behavior and a complex magnetic phase diagram due to the interaction between itinerant and local electrons. Recently, the electron emission property of CeB6 has received much attention because it has potential applications in replacing the commercial LaB6 cathode and serving as new-generation thermal cathodes. In addition, by comparison with other metal cathodes, it also possesses some advantages, such as a low work function, low volatility, high brightness, thermal stability and high mechanical strength. However, so far the thermionic emission properties of CeB6 single crystal surfaces except for the (100) surfaces have been rarely reported. Whether the different crystal surfaces of CeB6 contribute to the various interesting emission properties is main research purpose of the present work. In this paper, the (110), (111), (210) and (310) crystal surfaces of single crystal CeB6 are determined by the X-ray Laue diffraction method, and their thermionic emission current densities are measured at different temperatures and applied voltages. As a result, the maximum emission current densities of the (110), (111), (210) and (310) crystal surfaces at 1873 K are 38.4, 11.54, 50.4 and 20.8 A/cm2, respectively. When their cathode temperatures are all 1773 K, their maximum emission current densities are 15.2, 5.43, 28.0 and 11.44 A/cm2. In addition, when the cathode temperature decreases to 1673 K, their maximum emission current densities are 4.24, 0.9, 6.2 and 2.43 A/cm2. It means that the thermionic emissions are strongly anisotropic for the different crystal surfaces. In general, the maximum emission current density of (100) crystal surface of LaB6 single crystal is about 10 A/cm2 at 1700 K. By comparing the emission current density of CeB6 single crystal at 1773 K with that of LaB6 at 1700 K, it is found that the emission properties of (210) crystal surface are maybe close to those of LaB6. The work function values of the (110), (111), (210) crystal surfaces calculated by the Richardson-Dushman formula are 2.64, 2.71 and 2.40 eV, respectively. Among these, the (210) crystal surface possesses the smallest value of the work function, which is hopeful for being used as an electron source of scanning electron microscopy. Zero-field magnetoresistivity measurments confirm the transition temperatures of TQ=3.3 K and TN=2.4 K. Field-angle dependent magnetoresistivity measurments show that the electrical resistivity varies between 69 μupΩ·cm and 73 μupΩ·cm when the crystal rotates from the[001] to the[011] direction. This indicates that the electrical resistivity in a magnetic field is also anisotropic.
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Keywords:
- CeB6 /
- work function /
- magnetoresistance
[1] Mignot J M, AndréG, Robert J, Sera M, Iga F 2008 Phys. Rev. B 78 014415
[2] Tanaka Y, Staub U, Narumi Y, Katsumata K, Scagnoli V, Shimomura S, Tabata Y, Onuki Y 2004 Physica B 345 78
[3] Feyerherm R, Amato A, Gygax F N, Schenck A, Onuki Y, Sato N 1995 J. Magn. Magn. Mater. 140-144 1175
[4] Alistair S C, Gerd F, Dmytro S I 2016 Rep. Prog. Phys. 79 066502
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[6] Zhao Y M, Ouyang L S, Zou C Y, Xu J Q, Dong Y Z, Fan Q H 2010 J. Rare Earth. 28 424
[7] Daniel V, Sergiy P, Varvara P, Volodymyr F 2009 IEEE Trans. Electron Dev. 56 812
[8] Gu Z Z, Xi X L, Yang J C, Xu J J 2012 Fuel 95 648
[9] Zhou S L, Zhang J X, Liu D M, Bao L H 2009 J. Inorg. Mater. 24 793(in Chinese)[周身林, 张久兴, 刘丹敏, 包黎红2009无机材料学报 24 793]
[10] Bao L H, Zhang J X, Zhou S L, Zhang N, Xu H 2011 Chin. Phys. Lett. 28 088101
[11] Mahmoud B, Masayuki K, Toshiteru K, Hideaki O 2016 IEEE Trans. Electron Dev. 63 1326
[12] Nirpendra S, Sapan M S, Tashi N, Auluck S 2007 J. Phys.:Condens. Matter 19 346226
[13] Zhou S L, Zhang J X, Bao L H, Yu X G, Hu Q L, Hu D Q 2014 J. Alloys Compd. 611 130
[14] Lin Z L 1997 High Power Laser Part Beams. 9 591(in Chinese)[林祖伦1997强激光与粒子束 9 591]
[15] Bao L H, Tegus O, Zhang J X, Zhang X, Huang Y K 2013 J. Alloys Compd. 558 39
[16] Terzioglu C, Ozturk O, Kilic A, Goodrich R G, Fisk Z 2006 J. Magn. Magn. Mater. 298 33
[17] Bogach A V, GlushkovV V, Demishev S V, Samarin N A, Paderno Y B, Dukhnenko A V, Shitsevalova N Y, Sluchanko N E 2006 J. Solid State Chem. 179 2819
[18] Mizuno K, Magishi K I, Kawakami M, Saito T, Koyama K, Kunii S 2003 Physica B 329-333 597
[19] Nakao H, Magishi K, Wakabayashi Y, Murakami Y, Koyama K, Hirota K, Endoh Y, Kunii S 2001 J. Phys. Soc. Jpn. 70 1857
[20] Effantin J M, Mingod J R, Burlet P, Bartholin H, Kunii S, Kasuya T 1985 J. Magn. Magn. Mater. 47-48 145
[21] Sera M, Ichikawa H, Yokoo T, Akimitsu J, Nishi M, Kakurai K, Kunii S 2001 Phys. Rev. Lett. 86 1578
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[1] Mignot J M, AndréG, Robert J, Sera M, Iga F 2008 Phys. Rev. B 78 014415
[2] Tanaka Y, Staub U, Narumi Y, Katsumata K, Scagnoli V, Shimomura S, Tabata Y, Onuki Y 2004 Physica B 345 78
[3] Feyerherm R, Amato A, Gygax F N, Schenck A, Onuki Y, Sato N 1995 J. Magn. Magn. Mater. 140-144 1175
[4] Alistair S C, Gerd F, Dmytro S I 2016 Rep. Prog. Phys. 79 066502
[5] Mignot J M, Andre G, Sera M, Iga F 2007 J. Magn. Magn. Mater. 310 738
[6] Zhao Y M, Ouyang L S, Zou C Y, Xu J Q, Dong Y Z, Fan Q H 2010 J. Rare Earth. 28 424
[7] Daniel V, Sergiy P, Varvara P, Volodymyr F 2009 IEEE Trans. Electron Dev. 56 812
[8] Gu Z Z, Xi X L, Yang J C, Xu J J 2012 Fuel 95 648
[9] Zhou S L, Zhang J X, Liu D M, Bao L H 2009 J. Inorg. Mater. 24 793(in Chinese)[周身林, 张久兴, 刘丹敏, 包黎红2009无机材料学报 24 793]
[10] Bao L H, Zhang J X, Zhou S L, Zhang N, Xu H 2011 Chin. Phys. Lett. 28 088101
[11] Mahmoud B, Masayuki K, Toshiteru K, Hideaki O 2016 IEEE Trans. Electron Dev. 63 1326
[12] Nirpendra S, Sapan M S, Tashi N, Auluck S 2007 J. Phys.:Condens. Matter 19 346226
[13] Zhou S L, Zhang J X, Bao L H, Yu X G, Hu Q L, Hu D Q 2014 J. Alloys Compd. 611 130
[14] Lin Z L 1997 High Power Laser Part Beams. 9 591(in Chinese)[林祖伦1997强激光与粒子束 9 591]
[15] Bao L H, Tegus O, Zhang J X, Zhang X, Huang Y K 2013 J. Alloys Compd. 558 39
[16] Terzioglu C, Ozturk O, Kilic A, Goodrich R G, Fisk Z 2006 J. Magn. Magn. Mater. 298 33
[17] Bogach A V, GlushkovV V, Demishev S V, Samarin N A, Paderno Y B, Dukhnenko A V, Shitsevalova N Y, Sluchanko N E 2006 J. Solid State Chem. 179 2819
[18] Mizuno K, Magishi K I, Kawakami M, Saito T, Koyama K, Kunii S 2003 Physica B 329-333 597
[19] Nakao H, Magishi K, Wakabayashi Y, Murakami Y, Koyama K, Hirota K, Endoh Y, Kunii S 2001 J. Phys. Soc. Jpn. 70 1857
[20] Effantin J M, Mingod J R, Burlet P, Bartholin H, Kunii S, Kasuya T 1985 J. Magn. Magn. Mater. 47-48 145
[21] Sera M, Ichikawa H, Yokoo T, Akimitsu J, Nishi M, Kakurai K, Kunii S 2001 Phys. Rev. Lett. 86 1578
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