US4030963A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arc-melting preparation of single crystal LaB6 cathodes
Assignee: Energy Research and Development Administration ERDA
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Filing: 1976-01-27
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Granted: 1977-06-21
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Expires: 1996-01-27
Abstract
Abstract A method for preparing single crystals of lanthanum hexaboride (LaB6) by arc melting a rod of compacted LaB6 powder. The method is especially suitable for preparing single crystal LaB6 cathodes for use in scanning electron microscopes (SEM) and scanning transmission electron microscopes (STEM).
Inventors
- 👤 Edwin D. Gibson
- 👤 John D. Verhoeven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:08
CPC Classifications
C; C30; C30B; C30B13/00; C30B13/16; C30B13/22; C30B29/00; C30B29/10; Y; Y10; Y10S; Y10S117/00; Y10S117/905; Y10S117/911
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
179 words
A method for preparing single crystals of lanthanum hexaboride comprising: mounting two rods of compacted lanthanum hexaboride powder by one end as a first electrode on an electrode holder electrically connected to the positive terminal of a DC electrical power source the opposite end of each rod being free, said two rods of lanthanum hexaboride being mounted slidably longitudinally on the electrode holder, the rods being on the same longitudinal axis, the free end of one rod contacting the free end of the other rod; striking an arc, under an inert atmosphere, at the point of contact between the rods with a second electrode electrically connected to the negative terminal of the power source; increasing the power from the electrical source until a small zone of molten lanthanum hexaboride powder is formed at the space between the rods; and moving the second electrode slowly longitudinally along both rods, while maintaining the power constant, thereby forming a small moving zone of molten lanthanum hexaboride powder along the rods, to form a single rod of a single crystal of lanthanum hexaboride.
Claim 2
Independent Claim
179 words
A method for preparing single crystals of lanthanum hexaboride comprising: mounting two rods of compacted lanthanum hexaboride powder by one end as a first electrode on an electrode holder electrically connected to the positive terminal of a DC electrical power source the opposite end of each rod being free, said two rods of lanthanum hexaboride being mounted slidably longitudinally on the electrode holder, the rods being on the same longitudinal axis, the free end of one rod contacting the free end of the other rod; striking an arc, under an inert atmosphere, at the point of contact between the rods with a second electrode electrically connected to the negative terminal of the power source; increasing the power from the electrical source until a small zone of molten lanthanum hexaboride powder is formed at the space between the rods; and moving the second electrode slowly longitudinally along both rods, while maintaining the power constant, thereby forming a small moving zone of molten lanthanum hexaboride powder along the rods, to form a single rod of a single crystal of lanthanum hexaboride.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the lanthanum hexaboride rods are from about 1 mm to about 1 cm square in cross section.
Claim 4
Dependent Claim
18 words
The method of claim 2 wherein the lanthanum hexaboride rods are about 1 mm square in cross section.
Claim 5
Dependent Claim
14 words
The method of claim 2 wherein the power density is about 5 amps/mm.sup. 2.
Claim 6
Dependent Claim
20 words
The method of claim 3 wherein the inert atmosphere is selected from the group consisting of helium, argon and krypton.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-20 | 1980-12-20 | 1981-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-20 | 1984-12-20 | 1985-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-20 | 1988-12-20 | 1989-06-21 | $7700.00 | Window Closed / Lapsed |