Lanthanum Hexaboride Cathode Description
Lanthanum hexaboride cathode (LaB6 cathode, also referred to as lanthanboride cathode and LaB6 cathode) is an inorganic compound. With a melting point of 2 528 K, the LaB6 cathode is a refractory ceramic material. It is insoluble in water or hydrochloric acid and remains very stable in a vacuum. Stochiometric samples exhibit an intense violet to purple colour, while samples with excess boron (beyond LaB6.07) appear blue. Ion bombardment alters the colour from violet to emerald green. The LaB6 cathode exhibits superconductivity with a transition temperature of 0.45 K.
The properties of lanthanum hexaboride crystals enable the production of stable electron-emitting media with a work function of approximately 2.70 eV. The low work function allows higher currents at lower cathode temperatures compared with tungsten. Consequently, this results in a beam that is 10 times brighter and a lifetime 50 times longer than that of tungsten cathodes. In electron microscopy, these attributes allow a greater beam current to be focused on a smaller area of the sample, thereby improving resolution and reducing the frequency of cathode replacement.
Lanthanum Hexaboride Cathode Specifications
Product
|
Lanthanum Hexaboride
|
Structure
|
Polycrystalline
|
Symbol
|
LaB6-Cathode
|
Thermal Conductivity
|
47 W/mK (20℃)
|
CAS-Nr.
|
12008-21-8
|
Thermal Expansion
|
6.2 10-6K-1 (20–900℃)
|
Atomic Mass
|
203.78 g/mol
|
Electrical Resistivity
|
ca.15 µΩ·cm (20℃)
|
Density
|
4.72 g/cm³
|
Electrical Conductivity
|
6.65×10⁴ S/cm (20℃)
|
Melting Point
|
2 528 K
|
Current Density
|
150 A/cm² (1 950℃)
|
Hardness
|
87.5 RA
|
Electron Emission Work Function
|
2.6 eV
|
Bending Strength (σ)
|
200 MPa
|
Fracture Toughness (Kic)
|
3.0 MN/m3/2
|
Chemical Composition
LaB6 (% min.)
|
99.9%
|
B (% min.)
|
31%
|
Rare Earth Impurities
|
Non-RE Impurities
|
Ce
|
<120ppm
|
Fe
|
<250ppm
|
Pr
|
<150ppm
|
Si
|
<100ppm
|
Nd
|
<180ppm
|
Ca
|
<90ppm
|
Sm
|
<112ppm
|
C
|
<300ppm
|
Y
|
<250ppm
|
Mg
|
<100ppm
|
|
|
Ti
|
<100ppm
|
Lanthanum Hexaboride Cathode Applications
* Thermionic emission (cathode)
* Plasma source for plasma-enhanced chemical vapour deposition (PECVD)
* Vacuum electron beam welding machine
* Electron beam surface modification equipment
* Electron beam lithography device
* Transmission electron microscope
* Scanning electron microscope
* Instrument for surface analysis
* Devices for radiotherapy
Lanthanum Hexaboride Cathode Packaging
The LaB6 cathode from SAM is handled with care to minimise damage during storage and transport. This procedure maintains the product quality in its original state.
The prototyping service is available for other ceramic materials as well
Tonerde
Aluminiumnitrid
Bor nitrid
Silicon Carbide
Silicon Nitride
Zirconium Dioxide
Related Articles:
What is a Lanthanum Hexaboride Electrode?