Rare Earth Hexaboride Nanowires: General Synthetic Design and Analysis Using Atom Probe Tomography

Brewer, Joseph R.; Jacobberger, Robert M.; Diercks, David R.; Cheung, Chin Li

doi:10.1021/cm200258h

Cited by 59 publications

(42 citation statements)

References 32 publications

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“…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

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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.

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Section: Introductionmentioning

confidence: 99%

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

et al. 2015

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“…Especially, rare-earth metal hexaborides have numerous useful physical and chemical characteristics which make them important to investigate (Post et al, 1956;Futamoto et al, 1980;Otani and Ishizawa, 1996;Balakrishnan et al, 2004;Selvan et al, 2008;Wang et al, 2010;Ji et al, 2011;Brewer et al, 2011;Aprea et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Single crystalline LaB 6 nanowires are one of the most widely used electron emitter in electron gun, which can offer about 10 to 15 times higher brightness, higher emission stability, lower energy spread and longer service life than the tungsten cathodes utilized in a large variety of devices such as high-resolution electron microscopes, electron beam writing units, vacuum electron beam welding machines, microwave tubes, free electron lasers, X-ray tubes, electron beam surface reforming and electron beam lithography devices (Ahmed et al, 1975;Perkins et al, 1999;Chen et al, 2004;Wen et al, 2004;Zhang et al, 2006Zhang et al, , 2007Wang et al, 2009;Qin et al, 2010;Bao et al, 2011). Moreover, LaB 6 nanomaterials are candidates to motivate the new designs of nanoscale electronic devices operated at high temperatures with the need of enhanced electron collection and injection properties (Brewer et al, 2011). Also, LaB 6 has exceptional thermoelectric properties at low temperatures providing their usage in solid-state cryocooling, thermoelectric refrigerators, generators and single-photon detectors operating at temperatures near to the boiling point of liquid helium which serve in technical applications including quantum computing, quantum cryptography, homeland security, defect control in microchips, astronomy, chemical analysis and particle physics (Carlsson et al, 2005;Petrosyan et al, 2012;Jha et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Preparation of LaB<sub>6</sub> Powders via Calciothermic Reduction using Mechanochemistry and Acid Leaching

Ağaoğulları

Balcı

Öveçoğlu

et al. 2016

KONA

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This study reports a room temperature mechanochemical route for the synthesis of LaB 6 powders originated from related metal oxide powders as La 2 O 3 and B 2 O 3 . Ca granules and B 2 O 3 powders were respectively used as reducing agent and boron source in the experiments. This study is actually meaningful to create added value by using the native boron source of Turkey for the production of high-technology boron materials. Milling duration as the most important parameter of mechanochemistry was examined to reveal the ideal production conditions. Mechanochemically synthesized powders were subjected to selective HCl leaching in order to eliminate unwanted phases. Thermochemical software of HSC Chemistry TM program was utilized to determine the reaction probability and to estimate the predicted products. Characterization investigations were carried out by X-ray diffractometer (XRD), differential scanning calorimeter (DSC), particle size analyzer (PSA), stereomicroscope (SM), scanning electron microscope (SEM), transmission electron microscope/energy dispersive spectrometer (TEM/EDS) and atomic absorption spectrometer (AAS). Nanosized LaB 6 powders were achieved with/without an insignificant amount of Ca 3 (BO 3 ) 2 phase via mechanochemistry in a high-energy ball mill for 3 h and via leaching with 4 M and 6 M HCl. Lastly, the experimental outputs obtained by a calciothermic reduction were compared with those of magnesiothermic reduction.

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“…8 Thus, a lot of relevant research has been carried out on this kind of material with nanostructure attributes, especially on the low work function of REB 6 . [13][14][15] Problems are also found using this method. 9-12 While on account of the severe hygroscopicity of RCl 3 in even low degrees of moisture circumstances, it's difficult to obtain large-scale, high quality RB 6 nanowires through this method.…”

Section: Introductionmentioning

confidence: 99%

Single-crystalline La_xNd_1−xB₆ nanowires: synthesis, characterization and field emission performance

Zhang

Chen

et al. 2015

J. Mater. Chem. C

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We report the catalyst-free synthesis of uniform distributed single-crystalline La x Nd 1Àx B 6 nanowires by simply heating mixed La and Nd powders to the required temperature in an inlet flux of mixed gases (H 2 , Ar and BCl 3 ). FE-SEM, HRTEM, SAED, EDS, element mapping, XRD and Raman scattering resultsshow that the La x Nd 1Àx B 6 nanowires are structurally uniform and well-doped single crystals. Based on our experimental results, a dominant VLS-like mechanism with a self-catalytic growth mechanism was proposed and depicted conceptually. The nanowires display an excellent field emission performance with a low turn-on field value of B4.12 V mm À1 when evaluated as an electron emitter. Attempts were also made to understand the morphological influence of reaction time, reaction temperature and the proportion of the La and Nd powders.

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Rare Earth Hexaboride Nanowires: General Synthetic Design and Analysis Using Atom Probe Tomography

Cited by 59 publications

References 32 publications

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Preparation of LaB<sub>6</sub> Powders via Calciothermic Reduction using Mechanochemistry and Acid Leaching

Single-crystalline La_xNd_1−xB₆ nanowires: synthesis, characterization and field emission performance

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Rare Earth Hexaboride Nanowires: General Synthetic Design and Analysis Using Atom Probe Tomography

Cited by 59 publications

References 32 publications

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Effects of Nanoparticle Shape and Size on Optical Properties of LaB6

Preparation of LaB<sub>6</sub> Powders via Calciothermic Reduction using Mechanochemistry and Acid Leaching

Single-crystalline LaxNd1−xB6 nanowires: synthesis, characterization and field emission performance

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Single-crystalline La_xNd_1−xB₆ nanowires: synthesis, characterization and field emission performance