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- Q410318 subject Q7469270.
- Q410318 subject Q8307257.
- Q410318 subject Q8582934.
- Q410318 subject Q8645505.
- Q410318 abstract "Lanthanum hexaboride (LaB6, also called lanthanum boride and LaB) is an inorganic chemical, a boride of lanthanum. It is a refractory ceramic material that has a melting point of 2210 °C, and is insoluble in water and hydrochloric acid. It has a low work function and one of the highest electron emissivities known, and is stable in vacuum. Stoichiometric samples are colored intense purple-violet, while boron-rich ones (above LaB6.07) are blue. Ion bombardment changes its color from purple to emerald green.The principal use of lanthanum hexaboride is in hot cathodes, either as a single crystal or as a coating deposited by physical vapor deposition. Hexaborides, such as lanthanum hexaboride (LaB6) and cerium hexaboride (CeB6), have low work functions, around 2.5 eV. They are also somewhat resistant to cathode poisoning. Cerium hexaboride cathodes have a lower evaporation rate at 1700 K than lanthanum hexaboride, but they become equal at temperatures above 1850 K. Cerium hexaboride cathodes have one and half the lifetime of lanthanum hexaboride, due to the former's higher resistance to carbon contamination. Hexaboride cathodes are about ten times "brighter" than tungsten cathodes, and have 10–15 times longer lifetime. Devices and techniques in which hexaboride cathodes are used include electron microscopes, microwave tubes, electron lithography, electron beam welding, X-ray tubes, and free electron lasers. Lanthanum hexaboride slowly evaporates from the heated cathodes and forms deposits on the Wehnelt cylinders and apertures. LaB6 is also used as a size/strain standard in X-ray powder diffraction to calibrate instrumental broadening of diffraction peaks.LaB6 is a superconductor with a relatively low transition temperature of 0.45 K.".
- Q410318 thumbnail CaHexaboride.jpg?width=300.
- Q410318 wikiPageWikiLink Q1123417.
- Q410318 wikiPageWikiLink Q11475.
- Q410318 wikiPageWikiLink Q124131.
- Q410318 wikiPageWikiLink Q127995.
- Q410318 wikiPageWikiLink Q132560.
- Q410318 wikiPageWikiLink Q1365473.
- Q410318 wikiPageWikiLink Q174443.
- Q410318 wikiPageWikiLink Q1801.
- Q410318 wikiPageWikiLink Q213185.
- Q410318 wikiPageWikiLink Q2225.
- Q410318 wikiPageWikiLink Q2409.
- Q410318 wikiPageWikiLink Q2554501.
- Q410318 wikiPageWikiLink Q256845.
- Q410318 wikiPageWikiLink Q3296907.
- Q410318 wikiPageWikiLink Q3431241.
- Q410318 wikiPageWikiLink Q376044.
- Q410318 wikiPageWikiLink Q419302.
- Q410318 wikiPageWikiLink Q45621.
- Q410318 wikiPageWikiLink Q586386.
- Q410318 wikiPageWikiLink Q618.
- Q410318 wikiPageWikiLink Q743.
- Q410318 wikiPageWikiLink Q7469270.
- Q410318 wikiPageWikiLink Q783800.
- Q410318 wikiPageWikiLink Q8307257.
- Q410318 wikiPageWikiLink Q83327.
- Q410318 wikiPageWikiLink Q8582934.
- Q410318 wikiPageWikiLink Q8645505.
- Q410318 wikiPageWikiLink Q900134.
- Q410318 type ChemicalCompound.
- Q410318 type ChemicalSubstance.
- Q410318 type ChemicalObject.
- Q410318 type Thing.
- Q410318 type Q11173.
- Q410318 comment "Lanthanum hexaboride (LaB6, also called lanthanum boride and LaB) is an inorganic chemical, a boride of lanthanum. It is a refractory ceramic material that has a melting point of 2210 °C, and is insoluble in water and hydrochloric acid. It has a low work function and one of the highest electron emissivities known, and is stable in vacuum. Stoichiometric samples are colored intense purple-violet, while boron-rich ones (above LaB6.07) are blue.".
- Q410318 label "Lanthanum hexaboride".
- Q410318 depiction CaHexaboride.jpg.