LaB6 and CeB6 cathodes, Hitachi

Hitachi, Request a quoteLanthanum hexaboride (LaB6) and cerium hexaboride (CeB6) cathodes are ideal for many small spot size applications such as SEM, TEM, surface analysis and metrology, and for high current applications such as microwave tubes, lithography, electron-beam welders, X-ray sources and free electron lasers. Applied Physics Technologies has decades of experience in research, development, and manufacturing of LaB6 and CeB6 cathodes. We can provide the cathodes you need for replacement, OEM, and custom applicationsThe unique properties of hexaboride crystals provide stable electron-emitting media with work functions near 2.65 eV. The low work function yields higher currents at lower cathode temperatures than tungsten, which means greater brightness (or current at the beam focus) and longer cathode life. Typically, these cathodes exhibit 10 times the brightness and more than 10 times the service life of tungste...

Hitachi, Request a quote

Lanthanum hexaboride (LaB6) and cerium hexaboride (CeB6) cathodes are ideal for many small spot size applications such as SEM, TEM, surface analysis and metrology, and for high current applications such as microwave tubes, lithography, electron-beam welders, X-ray sources and free electron lasers. Applied Physics Technologies has decades of experience in research, development, and manufacturing of LaB6 and CeB6 cathodes. We can provide the cathodes you need for replacement, OEM, and custom applications

The unique properties of hexaboride crystals provide stable electron-emitting media with work functions near 2.65 eV. The low work function yields higher currents at lower cathode temperatures than tungsten, which means greater brightness (or current at the beam focus) and longer cathode life. Typically, these cathodes exhibit 10 times the brightness and more than 10 times the service life of tungsten cathodes. In electron microscope applications, these characteristics translate to more beam current in a smaller spot at the sample, improved resolution, and less frequent cathode replacement.

For applications with large beam spot sizes, where large total current and current density are required, large, flat crystal faces of LaB6 or CeB6 can be the cathodes of choice. This regime is unsuitable for point sources such as field emitters, which are unable to provide sufficient total current, and has been thought of as the realm of the dispenser cathode. However, LaB6 and CeB6 may be more suitable, being particularly robust and resistant to chemical poisoning. They have modest vacuum requirements and long shelf life, and need only be brought up to operating temperature to provide emission, eliminating the activation procedure required of dispenser cathodes. They can provide long-term, stable operation at current densities up to 50 A/cm2, and may be fabricated in a variety of shapes and with many different heating and mounting configurations.

LaB6 and CeB6 are the materials of choice for high current cathodes in a variety of advanced and custom applications. The performance and lifetime of the hexaboride cathode are determined by several factors: vacuum level, cathode temperature, impurity level, crystal orientation, tip shape, and mount design.

Vacuum requirements are more stringent for hexaboride emitters than for tungsten in order to minimize carbon contamination. In laboratory tests, CeB6 has proven to be more resistant to the negative impact of carbon contamination than LaB6, which gives it an edge in potential cathode lifetime.

Excessive operating temperatures accelerate evaporation, thus decreasing the life of the cathode. Care must be taken to properly optimize cathode temperature to obtain the required emission without overheating the crystal. CeB6 has another advantage over LaB6 relating to lifetime: its evaporation rate at normal operating temperatures near 1800 K is lower than that of LaB6 . So long as care is taken to operate the cathode below 1850 K, CeB6 should maintain an optimum tip shape longer, and therefore last longer.

  CeB6 <100> LaB6 <100> Tungsten Filament
Brightness (A/cm2-sr) 107 107 106
Short-term beam current stability % RMS <1 <1 <1
Typical service life (hr) 1,500+ 1000+ 30-100
Operating vacuum (torr) 10-7 10-7 10-5
Work function (eV) ~2.65 ~2.70 4.5
Evaporation rate (g/cm2-sec) 1.6 x 10-9 2.2 x 10-9 NA

A comparison of electron emission characteristics of LaB6, CeB6 and tungsten at typical operating temperatures

Code Title Type Application Pack Size Availability Price Updated: 23-04-2024
EMS80924-HT LaB6 and CeB6 cathodes, Hitachi CeB6, 60/5 TEM Each No ETA Quote only Quote
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EMS80924-L-HT LaB6 and CeB6 cathodes, Hitachi LaB6, 90/5 TEM Each No ETA Quote only Quote
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EMS80924-L-S LaB6 and CeB6 cathodes, Hitachi LaB6, 90/16 SEM Each No ETA Quote only Quote
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EMS80924-L-T LaB6 and CeB6 cathodes, Hitachi LaB6, 90/16 TEM Each No ETA Quote only Quote
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EMS80924-S LaB6 and CeB6 cathodes, Hitachi CeB6, 90/16 SEM Each No ETA Quote only Quote
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EMS80924-T LaB6 and CeB6 cathodes, Hitachi CeB6, 90/16 TEM Each No ETA Quote only Quote
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