Synthesis and properties of nanostructured dense LaB6 cathodes by arc plasma and reactive spark plasma sintering

Zhou, Song; Zhang, Jiuxing; Liu, Danmin; Lin, Zulun; Huang, Q.; Bao, Lihong; Ma, Ruguang; Wei, Yintao

doi:10.1016/j.actamat.2010.05.031

Cited by 67 publications

(39 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lanthanum hexaboride (LaB 6 ), characterized by high brightness, thermal stability, low volatility, and high mechanical strength, is a very attractive material in thermionic electron emitter also due to its low-work function, high melting point, and strong covalent bond of B-B atom in its structure [1][2][3][4][5][6]. In recent years, much attention has been drawn to its optical properties since Schelm et al reported the excellent performance of strong absorption in near infrared (NIR) range and the high transparency in visible light (VL) range exhibited by window samples with a LaB 6 nanoparticle-doped polymer laminate [7].…”

Section: Introductionmentioning

confidence: 99%

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

et al. 2015

Self Cite

View full text Add to dashboard Cite

The optical response of lanthanum hexaboride (LaB 6 ) nanoparticles has been investigated by both theoretically and experimentally. The LaB 6 nanoparticles obtained by solid-state reaction could avoid serious surface oxidization and exhibit excellent optical performance. The discrete dipole approximation (DDA) has been used to investigate the optical response of LaB 6 nanoparticles with different sizes and different shapes. The calculation results coincide with the experimental results and reveal that the largest extinction peak value appears at 60 nm for cubic particles and 40 nm for spherical particles, respectively. Our calculation results show that the existence of the largest extinction peak value is not only due to the surface oxides but also relate to the particle shape of LaB 6 compound. In addition, the LaB 6 nanoparticles with cubic and spherical shapes exhibit different optical responses, and the cubic particles exhibit stronger near infrared (NIR) extinction than spherical particles. With increasing particle size, the extinction peak value of spherical particle decreases more rapidly than that of cubic ones.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, when the measurement temperature increase to 1873 K, the value of microstructured LaB 6 reaches to 33.26 A/cm 2 , which is higher than 27.93 A/cm 2 of nanostructured LaB 6 . According to previous investigation [14], for the LaB 6 with grain size 160 nm (99.99% purity), its maximum emission current density was 56.81 A/cm 2 at 1873 K, which is much higher than the low purity one (94% purity) in the same grain size condition. Therefore, it can be inferred that the impurity phase is harmful for the emission current density.…”

Section: The Effects Of Grain Size and Sample Purity On The Thermionimentioning

confidence: 94%

“…In order to study the effects of grain size and sample purity on LaB 6 thermionic emission properties, we have systematically discussed the emission current density of LaB 6 with grain size 150 nm (94% purity), 160 nm (99.99% purity) [14] and 5 μm (99.99% purity). Figure 5 shows the dependence of thermionic emission current density on the applied voltage of LaB 6 with grain size 150 nm (94% purity) and 5 μm (99.99% purity).…”

Section: The Effects Of Grain Size and Sample Purity On The Thermionimentioning

confidence: 99%

“…Up to now, the high cost and poor properties of coarse polycrystalline LaB 6 were considered as a representative barrier limit its application. However, Zhou et al [12][13][14] successfully prepared the bulks LaB 6 polycrystalline by spark plasma reactive sintering (SPS) the La and B powder at 1250-1400 °C. The sintered sample exhibits excellent thermal emission and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effect of precursor boron nanopowder on the microstructure and emission properties of LaB₆cathode materials

Bao

Zhang

Zhou

et al. 2011

Phys. Status Solidi C

View full text Add to dashboard Cite

Two different structured boron sources have been used for the fabrication of LaB6 ceramics and their effects on the sintering temperature, microstructure and emission properties were investigated. The results show that the reaction temperature of amorphous boron and La to form LaB6 is 1200 °C, which is 150 °C lower than the reaction using crystalline boron. The grain size of LaB6 prepared by amorphous boron and La is 150 nm, which is much smaller than that of crystalline boron ∼2 μm at the same sintering condition. With the grain size decreasing from 5 μm to 150 nm, the LaB6 thermionic emission current density increases significantly and the field emission turn‐on field decreases from 1500 V to 1300 V. Using amorphous boron nanopowder can not only enhance the microstructure but also improve the emission properties. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

“…The addition of scandium oxide to Ba-W dispenser thermionic cathodes can improve the emission by a factor of tens to hundreds at the same operating temperature. The cathodes like Ir 2 La, Ir 5 Ce and LaB 6 can provide current densities of 50-100 A/cm 2 , but the required operating temperatures are as high as 1600-1800 • C [3,4]. The only thermionic cathode candidate for the continuously improved vacuum devices in high emission current is the scandate cathode, considered as the next generation high emission cathode which has attracted great interest [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

High current density Sc2O3-W matrix dispenser cathode

Wang

Zhang

Liu

et al. 2011

Sci. China Inf. Sci.

View full text Add to dashboard Cite

Sc 2 O 3 -W matrix dispenser cathodes have been prepared by powder metallurgy method and tested in Pierce electron guns. The emission current density can reach 72 A/cm 2 at 900 • C and over 100 A/cm 2 can be achieved at a temperature higher than 950 • C. The emission improves and then keeps stable with time throughout the life testing period of 330 h at a continuous loading of 88 A/cm 2 pulsed current density with a pulse width of 10 μs and duty cycle of 0.2%. The cathode surface is covered by a semiconductor multilayer composed of Ba, Sc and O. The emission behavior of the cathode can be explained by a semiconductor model. CitationWang J S, Zhang X Z, Liu W, et al. High current density Sc2O3-W matrix dispenser cathode. Sci China Inf Sci, 2012, 55: 98-105,

show abstract

Synthesis and properties of nanostructured dense LaB6 cathodes by arc plasma and reactive spark plasma sintering

Cited by 67 publications

References 21 publications

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

The effect of precursor boron nanopowder on the microstructure and emission properties of LaB₆cathode materials

High current density Sc2O3-W matrix dispenser cathode

Contact Info

Product

Resources

About

Synthesis and properties of nanostructured dense LaB6 cathodes by arc plasma and reactive spark plasma sintering

Cited by 67 publications

References 21 publications

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

The effect of precursor boron nanopowder on the microstructure and emission properties of LaB6cathode materials

High current density Sc2O3-W matrix dispenser cathode

Contact Info

Product

Resources

About

The effect of precursor boron nanopowder on the microstructure and emission properties of LaB₆cathode materials