Review of $\hbox{LaB}_{6}$, Re-W Dispenser, and $\hbox{BaHfO}_{3}$-W Cathode Development

Taran, Anatoliy; Voronovich, Daniel; Plankovskyy, Sergiy; Paderno, V. N.; Филипов, В. Б.

doi:10.1109/ted.2009.2015615

Cited by 44 publications

(17 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Typical transition metals consist of Zr, Hf, Ti, and V. The improvement in mechanical properties is attributed to the interface between the two phases in the eutectic. Additionally, this material system has also shown significant improvements in thermionic emission current density when compared with standard single crystal LaB 6 [11,12]. LaB 6 /VB 2 was shown to have an order of magnitude improvement in current density when compared to single crystal LaB 6 [12].…”

Section: Introductionmentioning

confidence: 99%

Work function characterization of directionally solidified LaB6–VB2 eutectic

et al. 2017

View full text Add to dashboard Cite

With its low work function and high mechanical strength, the LaB/VB eutectic system is an interesting candidate for high performance thermionic emitters. For the development of device applications, it is important to understand the origin, value, and spatial distribution of the work function in this system. Here we combine thermal emission electron microscopy and low energy electron microscopy with Auger electron spectroscopy and physical vapor deposition of the constituent elements to explore physical and chemical conditions governing the work function of these surfaces. Our results include the observation that work function is lower (and emission intensity is higher) on VB inclusions than on the LaB matrix. We also observe that the deposition of atomic monolayer doses of vanadium results in surprisingly significant lowering of the work function with values as low as 1.1eV.

show abstract

Section: Introductionmentioning

confidence: 99%

Work function characterization of directionally solidified LaB6–VB2 eutectic

et al. 2017

View full text Add to dashboard Cite

show abstract

“…4 One particular subgroup in this large class of materials includes the hexaborides, which are being used as additives for wear-and corrosion-resistant engineering components, 5 for decorative and thermionic coatings, 6 and for electron emission sources. 7 Here, we demonstrate the first instance of the preparation of boride materials by an efficient combustion synthesis technique at a temperature of 3201C. Combustion synthesis has been utilized since the 1990s for preparing many types of nanocrystalline oxides, as has been shown in countless studies.…”

Section: Introductionmentioning

confidence: 87%

“…B oride compounds have proven to be essential for myriad applications such as reinforcing phases in metal–matrix composites 1–3 and armor materials 4 . One particular subgroup in this large class of materials includes the hexaborides, which are being used as additives for wear‐ and corrosion‐resistant engineering components, 5 for decorative and thermionic coatings, 6 and for electron emission sources 7 . Here, we demonstrate the first instance of the preparation of boride materials by an efficient combustion synthesis technique at a temperature of 320°C.…”

Section: Introductionmentioning

confidence: 99%

Unique Preparation of Hexaboride Nanocubes: A First Example of Boride Formation by Combustion Synthesis

Kanakala

Rojas-George

Graeve

2010

Journal of the American Ceramic Society

View full text Add to dashboard Cite

Nanocubes of LaB6 and Sm0.8B6 have been synthesized using low‐temperature combustion synthesis, a technique that had only been used previously for the preparation of oxides. The hexaboride nanocubes were prepared using lanthanum nitrate or samarium nitrate, carbohydrazide, and boron powders. The furnace temperature for synthesis was kept at 320°C, lower than the typical temperature values used in combustion processes for the preparation of oxides. After synthesis, the nanocubes were characterized using X‐ray diffraction, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The combustion process was analyzed using differential scanning calorimetry, which shows that the formation of the carbohydrazide and nitrate melts as well as the formation of a complex between metal ions and carbohydrazide are crucial steps for the reaction. The technique results in high‐purity powders with a unique cubic morphology, in which the corners of the cubes can be used as point sources for efficient electron emission.

show abstract

“…The physical mechanisms leading to the specific emissive behavior of the composite are not fully established. The hypothesis of an easier diffusion of lanthanum to the external surface through the LaB 6 /ZrB 2 interfaces and fiber surfaces has been proposed [10]. An increased emissivity of the LaB 6 /ZrB 2 interfaces due their distinct electronic structure, and the surrounding stress field has also been discussed.…”

Section: Introductionmentioning

confidence: 99%

Local investigation of the emissive properties of LaB6–ZrB2 eutectics

et al. 2017

View full text Add to dashboard Cite

LaB 6-ZrB 2 composites obtained by directional solidification at eutectic composition have been investigated by low-energy electron microscopy (LEEM) and thermal emission electron microscopy (ThEEM). The transitions from the mirror electron microscopy mode to the LEEM mode for the hexa-and diborides indicate lower work functions of the two phases when embedded in the composite compared to the corresponding single phases. In the composite, the work function of the ZrB 2 fibers is similar to that of the matrix and ThEEM images display a brighter contrast for the fibers. This is explained by the thermally activated diffusion of La on the fiber surface.

show abstract

Review of $\hbox{LaB}_{6}$, Re-W Dispenser, and $\hbox{BaHfO}_{3}$-W Cathode Development

Cited by 44 publications

References 15 publications

Work function characterization of directionally solidified LaB6–VB2 eutectic

Work function characterization of directionally solidified LaB6–VB2 eutectic

Unique Preparation of Hexaboride Nanocubes: A First Example of Boride Formation by Combustion Synthesis

Local investigation of the emissive properties of LaB6–ZrB2 eutectics

Contact Info

Product

Resources

About