LaB6 Filaments

Denka Model 3 LAB6 Filaments

Advantages of LaB6 Filaments

The use of an electron beam enables not only observation of the submicron world (TEMs, SEMs, and X-ray microanalyzers) but also processing with submicron precision (electron beam lithography systems). The optimum filament material for use in these instruments would possess the following properties:

  • Low potential barrier (work function)
  • High melting point and stability at high temperatures
  • Low vapor pressure so as to reduce evaporation loss
  • Chemical stability

The relative drawbacks of tungsten filaments are: work function of 4.7eV, insufficient beam current density, and a short service life. LaB has a work function of 2.66eV, thus easily emitting electrons, and is a relatively stable material, so it has been increasingly used as a material in filaments in preference to tungsten. Using LaB6 filaments with TEMs and SEMs, even with the electron beam narrowed down, it is possible to obtain enough beam current density to achieve better resolution and clear photographs with less noise. The principle advantage, however, is that LaB6 can be used in a stable condition for a much longer time.

Denka manufactures the industry's purest, highest quality LaB6 crystals for use in their filament tips, featuring:

  • High Brightness: A LaB6 beam is ten times brighter than tungsten, has superior resolution, and features a wide range of acceleration voltages. It provides sharp, clear pictures down to the smallest detail. The initial brightness of a Denka Model 3 filament (1X10 A/cm2. Str) is substantially better than that of competing, minivogel type filaments (typically 5X10 A/cm²-Str).
  • Long Life: Heat and vacuum are the final determinants of any filament tip's life, but at 1550° C and a vacuum of 10 Torr, a service life of about 500 hours can be expected.
  • Stability: Thanks to its simple and durable construction, every Denka Model 3 LaB Filament offers a stability of better than 3% per hour at 1550°
  • Interchangeability:Denka Model 3 LaB6 filaments are designed as direct replacements for tungsten filaments.

Standard Denka M-3 Filaments

Provided with a 90° cone angle and 15µ radius round tip.

Cat # Description Price
A40010 Philips $1,165.00
A40011 Philips $1,223.00
A40015 AMRAY $1,001.40
A40020 Cambridge $1,141.00
A40021 Cambridge $1,315.00
A40022 Cambridge $1,347.00
A40025 Hitachi $1,141.00
A40035 ISI SEMs (except DS-130) $1,141.00
A40040 ISI TEMs $1,141.00
A40041 ZEISS $1,141.00

Flat (Truncated) Tips

Flat tips are recommended for applications where stability and long lifetime are the prime considerations, and where some degree of brightness can be sacrificed. Flat tips are available in eight configurations:

90° Cone angle 20µ radius 60° Cone angle 20µ radius
90° Cone angle 40µ radius 60° Cone angle 40µ radius
90° Cone angle 60µ radius 60° Cone angle 60µ radius
90° Cone angle 100µ radius 60° Cone angle 100µ radius

Sharp Tips

Sharp tips are recommended for applications where initial brightness is the foremost consideration and where shorter lifetime can be accepted. Sharp tips are available in two configurations:

60° Cone angle 5µ radius 60° Cone angle 10µ radius

Denka M-3 LaB6 filaments A40005 to A40040 are available in flat & sharp tip configurations.
Please call or email Soquelec for more information.

Comparison of Tip Configurations Available with Denka M-3 LaB6 Filaments

Flat Tip Standard (Round) Tip Sharp Tip
Brightness About 5 times tdat of tungsten 2-5 x 10 A/cm Str About 10 times tdat of tungsten 1 x 10 A/cm Str Twice as bright as standard tips 2 x 10 A/cm Str
Saturation Mono spot at about 1400° C Mono spot at about 1500° C Almost tde same as standard tips
Crossover Large (11-13µm) Small (7-10µm) Small (7-10µm)
Angular Distribution Broad 3.3-4.2 x 10 rad Sharp 1.6 x 10 rad Sharp 1.6 x 10 rad
Used Temperature Low Temperature High Temperature High Temperature
Lifetime Long life (usable at low temperatures,and crystalized end changes slowly) Long life (but shorter tdan flat tips) Short
Operation Easy (tdanks to its large spot size and broad adjusting range) Not so difficult Difficult (tde point adjustment needed)
Stability High (invulnerable to tdermal expansion or vibration) High Middle (vulnerable to tde tdermal expansion or vibration. Adjustment is sometimes necessary)
Technology Needed Ordinary High Very high

All prices are in Canadian Dollars. To request a price quotation or for other inquiries, please contact us.

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