CN102479649A - Field emitter cathode of carbon fiber material - Google Patents

Abstract

The invention provides an electronic field emitter including carbon fibers generated by catalytically decomposing carbon-containing gas on small metal particles and a field emitter cathode. Each carbon fiber contains a grapheme lamellar crystal; and the grapheme lamellar crystals are arranged at certain angles relative to a fiber shaft, so that the peripheries of the carbon fibers basically consist of the edges of the grapheme lamellar crystals. The field emitter and the field emitter cathode can be applied to computers, televisions and other flat displays.

Description

The field emitter negative electrode of carbon fibre material

Technical field

The invention belongs to field of electronic materials, the concrete field emitter negative electrode that relates to a kind of carbon fibre material.

Background technology

So-called field emission material of field emission electron source or field emitter can be used in the various electronics application, for example vacuum electronic equipment, panel computer and television indicator, emission gare amplifier and klystron, and be used for illumination.

, many kinds use display screen, for example family expenses and business television, on knee and desktop computer, indoor and outdoors advertisement and information exhibition in using.Compare with the thick cathode-ray tube display (monitors) of most of TVs and desktop computer; Flat-panel monitor (rl; T panel display) only several inches thick. flat-panel monitor is essential for kneetop computer, and is applied in for many other and also has advantage on weight and the size.The kneetop computer flat-panel monitor uses liquid crystal at present, can be transformed into opaque state from pellucidity through applying weak signal of telecommunication liquid crystal.Be difficult to produce reliably dimensionally than being suitable for the bigger this display of kneetop computer.

Existing suggestion is with the substitute of plasma display as LCD. and wait from pixel unit (pixel oell) and produce image, and require bigger electrical power to come work in the small charged gas of display employing.

Have and propose to adopt the flat-panel monitor with negative electrode, this negative electrode uses field emission electron source, causes emissive material or field emitter on the spot, phosphor that in addition can be luminous under being bombarded by the field emitter electrons emitted.This display can provide the advantage of conventional cathode ray tube Visual Display; And the advantage of the thickness of other flat-panel monitor, weight and power consumption. United States Patent (USP) 4; 857; 799 and 5,015,912 disclose little end of adopting dove, phase or silicon to constitute, and (micro-tip) matrix addressing flat-panel monitor WO 94-15352, WO 94-15350 and the WO 94-285-1 of negative electrode disclose the flat-panel monitor that negative electrode wherein has the emitting surface of relatively putting down.

In two kinds of nanotube carbon structures, see clear showing up and caused emission.At Chem. Phys. Letters 233,63 (1955) and Mat. Res. Soc. Symp. Proc. Vol. in 359,99 (1995), L. A. Chernozatonskii etc. are 10 ^-5, 10 ^-6Electronics through graphite in the hair vacuum is transmitted in the film of preparation nanotube carbon structure in the various substrates. and these films strongly fragrantly each other connect by being in, the broken molecular composition of tubulose of alinement. and forms two kinds of tracheary elements: A-tube, its structure comprise that the formation diameter is the mono-layer graphite shape tubule of 10-30nm tow; B-tube; It comprises that the diameter that has taper shape or wear shape end, top is that 10-30nm great majority be the graphite-like pipe of multilayer. they have reported the sizable field-causing electron emission from these body structure surfaces, and think because in the highly dense generation of nano-scale tip field.At Mat. Res. Soc. Symp. Proc. Vol. in 359,93 (1995), B. H. Pishbine etc. have discussed test and the theory that causes the development of emitter array negative electrode about " buckytube " (being CNT) awkward silence at a meeting.

N. M. Rodr 1 guez etc. are at J. Ca tal. in 144,93 (1993), N. M .Rodriguez is at J. Mater. Res. 8; In 3233 (1993), discuss T pulls on the broken fiber that some hydrocarbon catalytic decomposition generated at the little grain husk of metal growth and performance. patent U. S. 5,149; 584, U. 5. 5,413,866, U. S. 5; 458,784, U. S. 5,618; 875 and U. S. 5,653,951 further disclose the application of this fiber.Still need a kind of electron field emission body flat-panel monitor, that be easy to obtain that is used for.

Summary of the invention

The present invention is directed to the current situation of above-mentioned prior art, a kind of electron field emission body that the little grain husk grain of metal is gone up the carbon fiber that is generated by the carbonaceous gas catalytic decomposition that is included in is provided.Every broken fiber all has Graphene platelet (graphene platelets), the graphene film crystalline phase for fiber axis with an angle in case the periphery of carbon fiber form by the edge of Graphene platelet basically.

The present invention also provides a kind of field emitter negative electrode that comprises the carbon fiber of the catalysis generation that is connected in substrate surface, and wherein the carbon fiber of catalysis generation (catalytically grown) is promptly pulled on the carbon fiber that is generated by the carbonaceous gas catalytic decomposition on little of metal.

These field emitters and field emitter negative electrode can be used for panel computer, TV and other kind display, vacuum electronic equipment, the emission gare amplifier, in klystron and the lighting apparatus. flat-panel monitor can be the plane or curved surface.

The carbon fiber that the present invention provides a kind of novel electronic field emitter, on small metal particles, generated by the carbonaceous gas catalytic decomposition, and the electron field emission body negative electrode that comprises the broken fiber that this catalysis generates.This broken fiber can be according to N. M. and Rodr iguoz etc. are at J. Cat.1 .144; In 93 (1993), N. M. Rodriguez is at J. Mater. Res. 8; Preparing described in 3233 (1993). in brief, under 600 ℃, in 10 % nitrogen-nitrogen current; The powdered-metal catalyst is reduced, and makes it then to be in the needed reaction temperature.The mixture of predetermined hydrogen, hydrocarbon and inert gas is incorporated in this system, and afterreaction begins to carry out.For example on iron, react at 600 ℃ of CO-H (4: 1) mixture.

When used herein; " carbon fiber that catalysis generates " meaning is to pull on the carbon fiber that is generated by the carbonaceous gas catalytic decomposition on little of metal; Every this carbon fiber all has the Graphene platelet, the graphene film crystalline phase for fiber axis with an angle in case the periphery of carbon fiber form by the edge of Graphene platelet basically. said angle can be acute angle or 90 °.

The carbon fiber that catalysis generates is the good electron field emitter, and in the time of on being connected to substrate, it is very useful as electron field emission body negative electrode.

The whole bag of tricks can be used to the carbon fiber that catalysis generates is connected in the substrate.Cause under the condition of equipment of emitter cathodes producing park; And under its service condition; As be typically vacuum condition and be up to about 450 ℃ temperature; This jockey must sustain and keep its integrality. and therefore, organic material generally is not suitable for particle is connected in the substrate, but many inorganic material and broken poor bonding have further limited the selection of materials used.

Preferable methods is: will comprise the carbon fiber of catalysis generation and the charging of glass dust, metal dust or metallic paint or its mixture, and to substrate, fire the slurry of processing pattern that this is done with desirable pattern screen printing then.For using widely; For example those require better definition; Preferable methods comprises: screen printing is carried out in the charging that will further comprise light trigger and photohardenable monomer; Again dry charging is carried out light pattern (photopatterning), fire the slurry that this processes pattern then.

Substrate can be any material that paste compound can be adhered.If slurry is non-conductive, and use at the bottom of the nonconductive matrix, then need the electric conductor film to apply the member of voltage and supplies electrons as cathode electrode and to the carbon fiber that catalysis generates.Silicon, glass, metal or refractory material (for example oxidation inscription) can be used as substrate. for display application; Preferred substrate is a glass; Preferred especially soda-lime glass. in best conductance on glass, silver paste can be in air or nitrogen, fire in advance on glass at 500-550 ℃. and the conductive layer that forms like this is the available transmission body charging shoe brush of impressing in the above then.

The emitter charging that is used for screen printing contains broken fiber, organic media, solvent, the surfactant that catalysis generates usually, and low softening point glass dust, metal dust or metallic paint or its mixture.The effect of medium and solvent is in the slurry with the suitable rheology that can be used for conventional pattern-making technology (like screen printing), to suspend and discrete particles component (being solid).Many known such media are arranged in the art. the example of applicable resin is a celluosic resin; Like ethyl cellulose; And the alkyd resins of various molecular weight. the example of useful solvent is BC, butyl carbitol acetate vinegar, dibutyl carbitol (DBC), strongly fragrant phthalic acid two fourth vinegar and abundant article alcohol. allocate these and other solvent into, to reach desirable viscosity and volatility requirement. surfactant can be used to improve the dispersion of particle. the sufficient conventional surfactant of organic acid (like oleic acid and stearic acid) and organic phosphoric acid intoxicated (like lecithin or Gafac phosphoric acid vinegar).

Require glass dust enough softening under firing temperature, so that bonding with the carbon fiber of substrate and catalysis generation.Can adopt the glass of lead glass powder and other low softening point, like calcium borosilicate or zinc borosilicate.But the composition that has the screen printing of high electrical conductivity if desired, then slurry also contains metal, for example silver or golden. in the slurry total weight, slurry contains the solid of 40wt %-60wt % usually.These solids comprise broken fiber and glass dust and/or the metal component that catalysis generates. the variation of combination can be used to regulate the final thickness of viscosity and printing material.

Emitter charging adopt usually the carbon fiber that grinds catalysis and generate, organic media, surfactant, solvent and or the mixture of low softening point glass dust, metal dust or metallic paint or its mixture make. this slurry mix can adopt well-known screen printing technology, for example through adopting 165-400 sieve meshes not lure the steel screen cloth to come screen printing. slurry can continuous film or with the form deposition of hoped pattern.When substrate is glass, so slurry in nitrogen, 350 ℃-500 ℃, preferably under about 450 ℃ temperature, fired about 10 minutes.If do not contain oxygen in the atmosphere,, then can adopt higher firing temperature for the substrate that can bear higher temperature.Yet; Organic component in the charging has been volatilized under 350 ℃-450 ℃ effectively; Staying the composition layer that the carbon fiber that generated by catalysis and glass and/or metallic conductor are formed. in the sintering procedure in nitrogen, the carbon fiber of catalysis generation has experienced imperceptible oxidation or other chemistry or physical change.

If the slurry of screen printing is wanted light pattern (Dhotopatterned); Then this oar material contains light trigger and optical hardening monomer, the optical hardening monomer for example comprise at least a contain at least a polymerizable thiazolinyl (ethylenic group) but alkene property (ethylenically) unsaturated compound of addition polymerization.

Employing comprises the dull and stereotyped emission measurement device of two electrodes, and one of them electrode is as anode or collector electrode, and another carries out the field emission test as negative electrode to resulting sample.Negative electrode is formed by being installed in the copper billet that gathers in four atmosphere ethene (PTFE) bearings (holder).Copper billet is accommodated among the PTFE of 1 inch * l inch (2.5cm * 2.5 cm) area, and the sample substrate is installed on the copper billet, forms between copper billet and sample substrate through copper strips to electrically contact. and high-voltage connection is connected on the copper billet.Anode is with a variable range and sample keeping parallelism, in case still this distance is selected, for the measurement of the given sample of a cover, its keeps fixing.Except as otherwise noted, adopt the spacing of 1.25mm.Anode is made up of the glass plate of the oxidation relation by marriage tin that scribbles the deposit through chemical vapor deposition. applies with the white phosphor based on ZnS of standard, Phosphorp-31, the Type 139 that obtains from Blectronic Space Products International then. an electrode is connected on the oxidation relation by marriage tin coating.

Experimental rig is inserted in the vacuum system, and this system is evacuated to and is lower than 1*10 ^-6-(1.3*10 ^-4Pa) pressure of foundation.One negative voltage is applied on the negative electrode, measures emission current, as the function of applying voltage.

EmbodimentThe carbon fiber that catalysis generates with form of powder from catalyticMaterialsLtd, 12 old Stable Drive, Mansfield, MA. obtain.The carbon fiber that this catalysis of 0.1513 gram is generated joins 0. 1502 gram glass (Bayer PK 8701; CAS registration number 65997-18-4) and in the 1.5012 grams organic media commonly used, wherein organic media mainly comprises the ethyl cellulose in the article alcohol of dispelling.These components are mixed on the glass plate grinder and are reached 75 and change; To form the emitter slurry. method preparation below the silver-containing glass substrate of pre-burned is adopted: will carry out screen printing at the silver powder in organic ethyl cellulose class medium commonly used and the mixture of low melt glass dust, and then under 525 ℃, fire.Adopt the screen cloth of 325 sieve meshes then; The pattern that 1cm2 expands foursquare emitter slurry by screen printing to the silver-containing glass substrate of pre-burned, subsequently this sample 120 ℃ dry 10 minutes down. the sample of doing was then fired 10 minutes in nitrogen, under 450 ℃.After firing, charging is in the coating that forms an adhesion in the substrate. and the method for the sample of firing described in to specifications carried out the field emission test. and applying under the voltage of 4500V, emission current is greater than 10 ^-9Amp.

Claims (1)

1. the field emitter negative electrode of carbon fibre material; It is characterized in that the carbon fiber that on small metal particles, generated by the carbonaceous gas catalytic decomposition; Every carbon fiber all has the Graphene platelet; The graphene film crystalline phase for fiber axis with an angle so that the periphery of broken fiber is made up of the edge of Graphene platelet basically, this angle can be acute angle or right angle.