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A lanthanum hexaboride hot cathode. Lanthanum hexaboride cathodes. Lanthanum hexaboride powdered. Lanthanum hexaboride (La B 6, 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. [1]
The sum of the first two ionization energies for europium, 1632 kJ·mol −1 can be compared with that of barium 1468.1 kJ·mol −1 and europium's third ionization energy is the highest of the lanthanides. The sum of the first two ionization energies for ytterbium are the second lowest in the series and its third ionization energy is the ...
The mean oxidation number for the boron atoms is then simply the ratio of hydrogen to boron in the molecule. For example, in diborane B 2 H 6, the boron oxidation state is +3, but in decaborane B 10 H 14, it is 7 / 5 or +1.4. In these compounds the oxidation state of boron is often not a whole number.
Chemical formula Synonyms CAS number LaAlO 3: lanthanum aluminate: 71496–78–1 LaB 6: lanthanum boride: 12008–21–8 LaBr 3: lanthanum bromide: 13536–79–3 La(CHO 2) 3: lanthanum formate: 2081–11–0 LaC 2: lanthanum carbide: 12071–15–7 LaCl 3: lanthanum chloride: 10099–58–8 LaCl 3 •3H 2 O: lanthanum chloride trihydrate ...
Cerium hexaboride (Ce B 6, also called cerium boride, CeBix, CEBIX, and (incorrectly) CeB) is an inorganic chemical, a boride of cerium. It is a refractory ceramic material. It has a low work function , one of the highest electron emissivities known, and is stable in vacuum .
The borides can be classified loosely as boron rich or metal rich, for example the compound YB 66 at one extreme through to Nd 2 Fe 14 B at the other. The generally accepted definition is that if the ratio of boron atoms to metal atoms is 4:1 or more, the compound is boron rich; if it is less, then it is metal rich.
The gram-atom is a former term for a mole of atoms, and gram-molecule for a mole of molecules. [7] Molecular weight (M.W.) (for molecular compounds) and formula weight (F.W.) (for non-molecular compounds), are older terms for what is now more correctly called the relative molar mass (M r). [8]
Lanthanum(III) bromide (LaBr 3) is an inorganic halide salt of lanthanum. When pure, it is a colorless white powder. The single crystals of LaBr 3 are hexagonal crystals with melting point of 783 °C. It is highly hygroscopic and water-soluble. There are several hydrates, La 3 Br·x H 2 O, of the salt also known. It is often used as a source of ...