Emission properties and back-bombardment for CeB6 compared to LaB6

Bakr, Mahmoud; Kawai, Masayuki; Kii, Toshiteru; Zen, Heishun; Masuda, Kai; Ohgaki, Hideaki

doi:10.1063/1.4908004

Cited by 12 publications

(5 citation statements)

References 16 publications

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“…Considering the property of thermionic emission of LaB 6 the emission rate might change with temperature [22]. The change in emission rate can be described in terms of temperature dependence of an effective work function.…”

Section: Work Functionmentioning

confidence: 99%

See 1 more Smart Citation

Study on anomalous photoemission of LaB₆ at high temperatures

Torgasin¹,

Morita²,

Zen³

et al. 2019

Phys. Scr.

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Photoemission is used for a large variety of experimental techniques for study of material properties. Further applications photoemission finds for electron beam generation. Development of photocathodes with high quantum efficiency requires sufficient microscopic understanding of photoemission processes. The LaB 6 is a well-known thermionic emitter, which can be used as a photocathode. Anomalous, thermally assisted increase of quantum efficiency was previously demonstrated for this material. The increase shows a bi-exponential rise with photon-energy dependent slopes. The photon-energy dependency indicates correlation of extracted current with electronic band structure. In this work, we have investigated possible mechanisms, which could be the reason for the anomalous dependence of photoemission current on the cathode temperature. In particular, the Fowler-DuBridge theory was modified to account for changes in the electron density of states. The results show negligible low influence of density of states structure. Finally, we make a suggestion regarding the modification of the electron escape probability, which can cause the increase in photoemission.

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Section: Work Functionmentioning

confidence: 99%

“…It is a significant variation. Moreover, the high temperature is benefiting the photoemission in contrary to the experience with the effective work function by thermionic emission [22]. This consideration excludes the possibility of significant modification of effective work function by heating.…”

Section: Work Functionmentioning

confidence: 99%

Study on anomalous photoemission of LaB₆ at high temperatures

Torgasin¹,

Morita²,

Zen³

et al. 2019

Phys. Scr.

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“…At present, LaB 6 and CeB 6 are mainly used in the cathode of electron source, due to their low work function, slow volatilization rate, and stable chemical properties. 6 In recent years, the special photothermal property of rare earth hexaborides (REB 6 ) has been found, that is, strong absorption for near-infrared light, 7,8 which make them to be used as thermal insulation 9,10 and photothermal material. 11,12 In addition, the excellent high-temperature mechanical properties of REB 6 -transition metal diborides (TMB 2 ) eutectic materials have also attracted much attention.…”

Section: Introductionmentioning

confidence: 99%

Preparations of lanthanum hexaboride (LaB₆) and cerium hexaboride (CeB₆)

2021

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Due to strong anti-poisoning ability, good emission stability, high emission current density, lanthanum hexaboride (LaB 6 ) and cerium hexaboride (CeB 6 ) have been maturely applied in electron emission emitter. In this paper, a new manufacturing method for LaB 6 (or CeB 6 ) powder was proposed by using La 2 O 3 (or CeO 2 ), B 4 C, and Al as raw materials. After high-temperature reaction in the range of 1673-1773 K and the following alkaline leaching at 90 • C, LaB 6 or CeB 6 powder with particle size of about 10 μm was obtained. Furthermore, by Al metal flux method, the obtained powder was used to manufacture single crystal block with size of several millimeters.

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“…Moreover, many of them are excellently thermionic cathode materials due to high electronic emission in high temperature, low work function, high chemical stability, high melting points (>2800 K). As the typical representative hexaboride cathode, LaB 6 and CeB 6 have gained much attention . Compared with LaB 6 , CeB 6 has a lower evaporation rate at high temperature, which makes it have a longer lifetime using as a thermionic cathode, presenting a better prospect in device applications.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Properties of High‐Quality Ce_xLa_yPr_yNd_0.05Gd_0.05B₆ Single Crystal by Optical Float‐Zone Technique

Ning¹,

Iitaka²,

Xu³

et al. 2019

Physica Status Solidi (a)

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The work functions of LnB 6 (Ln ¼ Pr, Nd, and Gd) at (100) plane are systematically studied by first-principles calculation based on density functional theory. It reveals that the work function of LnB 6 at (100) plane obeyssingle crystals are successfully prepared by the optical float-zone technique. The crystal quality and emission properties of single crystals are characterized by rotating target X-ray diffraction, X-ray single-crystal diffraction, X-ray Laue diffraction, and the thermal electron emission measurements. The results present that the as-grown single crystals are of high quality and lower work function than single crystal CeB 6 . The maximum emission current density of 60.69 A cm À2 obtained at 1873 K under the applied voltage of 4000 V belongs to the Ce 0.5 La 0.2 Pr 0.2 Nd 0.05 Gd 0.05 B 6 single crystal with (100) surface.

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Emission properties and back-bombardment for CeB6 compared to LaB6

Cited by 12 publications

References 16 publications

Study on anomalous photoemission of LaB₆ at high temperatures

Study on anomalous photoemission of LaB₆ at high temperatures

Preparations of lanthanum hexaboride (LaB₆) and cerium hexaboride (CeB₆)

Preparation and Properties of High‐Quality Ce_xLa_yPr_yNd_0.05Gd_0.05B₆ Single Crystal by Optical Float‐Zone Technique

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Emission properties and back-bombardment for CeB6 compared to LaB6

Cited by 12 publications

References 16 publications

Study on anomalous photoemission of LaB6 at high temperatures

Study on anomalous photoemission of LaB6 at high temperatures

Preparations of lanthanum hexaboride (LaB6) and cerium hexaboride (CeB6)

Preparation and Properties of High‐Quality CexLayPryNd0.05Gd0.05B6 Single Crystal by Optical Float‐Zone Technique

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Product

Resources

About

Study on anomalous photoemission of LaB₆ at high temperatures

Study on anomalous photoemission of LaB₆ at high temperatures

Preparations of lanthanum hexaboride (LaB₆) and cerium hexaboride (CeB₆)

Preparation and Properties of High‐Quality Ce_xLa_yPr_yNd_0.05Gd_0.05B₆ Single Crystal by Optical Float‐Zone Technique