Lanthanum hexaboride

Lanthanum hexaboride (CAS 12008-21-8), commonly designated LaB₆ or lanthanum boride, is a refractory rare earth compound combining lanthanum with a boron octahedral cage structure.

Where is Lanthanum hexaboride used?

• Electron microscopy and X-ray instrumentation: thermionic cathode for SEM, TEM and X-ray tubes
• XRD calibration: NIST-traceable diffraction standard for instrument line profiles and peak-position correction
• Electronics and solar PV: nano-grade NIR absorber in heat-shielding films and laser transmission welding
• Glazing, agricultural film and photovoltaic encapsulants: selective thermal management without visible-light attenuation
• Aerospace and defence: ion thruster cathodes requiring work function stability at high temperature
• Electric propulsion and electron-beam generation rely on its low work function (~2.4 eV) and thermal stability to about 1,600 °C.

Good to know: Cathode-grade material is characterised by oxygen ≤ 0.5 % and carbon ≤ 0.1 %, critical to downstream performance. Compared with tungsten hairpin filaments, sintered LaB₆ cathodes offer higher brightness, lower energy spread and longer service life.

Commercial specifications

• Purity on rare earth oxide basis: LaB₆/TREO ≥ 99 % (2N) to ≥ 99.9 % (3N), lot-specific
• Oxygen ≤ 0.5 %; carbon ≤ 0.1 % (cathode grade)
• Particle sizes: coarse −325 mesh; 1.5–18 µm; nanopowder 50–80 nm
• Product forms: sputtering targets and pre-sintered cathode blanks; lot sizes 100 g to 5 kg