45results about How to "Reduce the turn-on electric field" patented technology

The invention relates to a field electron emitting cathode based on the composite material of graphene/zinc oxide nanowire, comprising a conductive electrode and the composite material of graphene/zinc oxide nanowire, wherein the composite material of graphene/zinc oxide nanowire is positioned on the surface of the electrode, and consists of the graphene with the size ranging from 2 to 10 micronsand the zinc oxide nanowire with the length ranging from 1 to 2 microns and the diameter being 100 nanometers; and the turn-on field is lower than or equal to 1.7 volt/ microns, and the threshold field is lower than or equal to 4 volt/ microns. The filed emission electron source has the advantages of lower turn-on field, low threshold field, high emission current density, stable emission, easy preparation method and easy realization of industrialized volume production.

The application discloses a preparation method for a graphene field emitting cathode. The preparation method comprises the following steps of: adding graphene and metal soluble inorganic salts in an organic solvent in a preset ratio to prepare graphene electrophoresis solution with positive charges; using a conductive substrate as a cathode, placing an anode and the cathode in the graphene electrophoresis solution, externally adding an electric field to enable the graphene with positive charges to move towards the direction of the cathode, and deposit on the cathode, so as to obtain a graphene film doped with metal particles; drying the graphene film to obtain the graphene field emitting cathode. The application further discloses a graphene field emitting cathode. The preparation method and the graphene field emitting cathode disclosed by the application are capable of improving the electrical contact characteristic between graphene and a substrate, and improving conduction performance; meanwhile, due to the metal nano-particles, the roughness of the graphene surface is improved, the local electric field intensity of the graphene surface is enhanced, the turn-on electric field of the graphene field emitting cathode is remarkably reduced, and the field emitting current is increased.

The invention, which relates to the technical field of field emission, provides a carbon-nano-field emission cathode and a manufacturing method and application. The carbon-nano-field emission cathodecomprises a substrate, a graphene layer horizontally coated on the substrate, and a carbon nanotube array arranged on the graphene layer. Roots of all carbon nanotubes in the carbon nanotube array arein covalent linkage with the graphene layer. According to the invention, because the roots of all carbon nanotubes are in covalent linkage with the graphene layer, the interface resistance is extremely low and thus the carbon nanostructure has excellent conductivity, so that the opening electric field of the cathode is reduced obviously; the heat generated during the field emission process is lowand thus the cathode can be emitted stably at the high current, so that the operating current of the cathode is improved substantially. Moreover, because the three-dimensional covalent structure hasexcellent thermal conductivity, the emission stability of the cathode is improved.

The invention discloses an orientated-growth latticed high-performance carbon nano-tube field emission array, which comprises a conductive substrate and latticed orientated carbon nano-tube arrays grown on the substrate, wherein the carbon nano-tube arrays are distributed into a latticed shape and form an integral structure. By the technical scheme, the structural stability of small-size carbon nano-tube arrays is improved, the edge effect of the carbon nano-tube arrays is enhanced, and then a turn-on electric field and a threshold electric field are reduced to improve the emission current density. The orientated-growth latticed high-performance carbon nano-tube field emission array is suitable for field emission devices having high requirements on current emission performance, such as electron sources in an X ray source, a microwave amplifier, a field emission scanning electron microscope and the like.

The invention discloses a field emission cathode and a preparation method and application thereof. The field emission cathode comprises a conductive substrate, a graphene layer and a molybdenum disulfide and/or tungsten disulfide nanosheet layer, wherein the graphene layer and the molybdenum disulfide and/or tungsten disulfide nanosheet layer are sequentially formed on the surface of the conductive substrate. The preparation method of the field emission cathode, disclosed by the invention comprises the step of forming the graphene layer on the surface of the conductive substrate and the step of carrying out electrophoresis on the surface of the conductive substrate to form the molybdenum disulfide and/or tungsten disulfide nanosheet layer. The field emission cathode disclosed by the invention has the advantages of low turn-on field, large emission current and high stability of emission current. By the preparation method of the field emission cathode, the performance stability of the field emission cathode is ensured, and the production cost of the field emission cathode is reduced.

The invention discloses a method for preparing a bunchy bismuth nanostructure material, which comprises the following steps: performing ultrasonic cleaning of an alumina AAO template in an alcohol solution, performing electrodeposition by multi-potential step, and removing the alumina membrane so as to obtain the bunchy bismuth nanostructure material. The invention has simple preparation and high filling ratio. The invention also discloses the prepared bunchy bismuth nanostructure material which has a unique high-density nano-wire array structure, can receive various heat energy from the environment, and has wide commercial application perspectives.

The invention provides a preparation method and an application of a hydrogenated titanium dioxide nanotube array film. The preparation method comprises the following steps: cleaning an industrial titanium sheet, and chemically polishing; oxidizing at room temperature through a constant-voltage direct-current anodizing method; and carrying out heat treatment in a vacuum environment in a hydrogen-containing atmosphere, stopping the let-in of hydrogen, and naturally cooling to room temperature in an argon atmosphere to prepare the hydrogenated titanium dioxide nanotube array film. The hydrogenated titanium dioxide nanotube array film can be directly used as a field electron emission cold cathode. The preparation method enables the hydrogenated titanium dioxide nanotube array film having the characteristics of low turn-on field, large emission current density, good field emission stability, high repeatability and the like and directly used as the field electron emission to be prepared; and the preparation method can be used for the industrial production, enables the cold cathode field emitters having low prices to be prepared, and can be well applied in the field electron emission display cathode material field.

The invention relates to a preparation method of an N-doped SiC nanoneedle flexible field emission cathode material, and belongs to the technical field of material preparation. The preparation method comprises the following steps: preprocessing an organic precursor; forming a catalyst on a flexible substrate; placing the organic precursor and the flexible substrate in an atmosphere sintering furnace, heating to a temperature of 1700 DEG C to 1800 DEG C for thermal decomposition, then cooling to reduce the temperature to 1000 DEG C to 1200 DEG C, and finally reducing the temperature to a room temperature along with a furnace so as to obtain the N-doped SiC nanoneedle flexible field emission cathode material. According to the invention, preparation of the N-doped SiC nanoneedle flexible field emission cathode material is realized, the prepared N-doped SiC nanoneedle flexible field emission cathode material has a quite low unlatching electric field at different temperatures, and at the same time, the electron emission characteristic is also stable at a high temperature.

The invention discloses a method for preparing a zinc oxide nano-layer structure on a supportless carbon nano-tube film, which is characterized in that zinc oxide is evenly attached to the supportless carbon nano-tube film to form the zinc oxide nano-layer structure through thermal evaporation by using nitrogen as carrier gas, wherein the zinc oxide nano-layer has a needle-like structure; the length thereof is 1mu m; and the particle size of zinc oxide particles is about 100 nanometers. The method improves the field emission characteristic of a carbon tube, improves the field emission performance and increases the field emission current density with lower turn-on electric field and good emission stability; and compared with the prior art, the method has the advantages of simple manufacturing process, low cost and good repeatability, is particularly suitable for large-area manufacture, and can perform kinking and clipping.

The invention discloses an application of a P-doped SiC nano wire in a field emission cathode material. The P-doped SiC nano wire is a field emission cathode, an emission electric field is formed between the field emission cathode and a field emission anode when voltages are applied, and when the emission current density of the field emission cathode under a normal-temperature vacuum condition is 10 [mu]A/cm<2>, the unlatching field intensity is 0.42 to 0.65 V/[mu]m. The P-doped SiC nano wire provided by the invention has the advantages of low unlatching electric field, good electric field stability and high photoelectric performance.

The invention belongs to the field of crossing of a vacuum electronics technology and a novel carbon material technology and particularly relates to a graphene-based field emission cold cathode and apreparation method. The field emission cold cathode comprises a substrate and an emitter, wherein the substrate is taken as a conductive substrate and is a silicon wafer or a metal sheet; the emitteris a graphene film layer; the graphene film layer is in close contact with the substrate; the thickness of the graphene film layer is 20-180 microns; and the graphene film layer is formed by grapheneclusters of which the particle sizes are 15-45 microns. The graphene-based cold cathode provided by the invention can be prepared by using the method, is in an array form, has good performance advantages of a low starting electric field, a low threshold electric field and high emission current, and can be applied to the fields, such as field emission display (FED) as an excellent electronic source.

The invention relates to a preparation method for a ZnO/ZnS heterostructure nanocone array, and the method is used for solving the problem that the existing nanometer materials with a special appearance structure have higher turn-on field or threshold field to cause poor field emission property. The method comprises the following steps of: 1, cleaning a monocrystalline silicon slice, sputtering a nanometer gold film on the monocrystalline silicon slice so as to be used as a silicon substrate; 2, mixing zinc oxide powder and zinc sulfide powder so as to be used as a source material, taking germanium powder as a catalyst, placing the source material in a high temperature-resistant container and in a high-temperature reacting furnace, and placing the catalyst and the silicon substrate at the lower course of the source material; 3, sealing the high-temperature reacting furnace, vacuumizing, introducing inert gas, heating, keeping temperature constant, naturally cooling to the room temperature, stopping the introduction of the inert gas, and taking out the silicon substrate, thus obtaining yellowish white powder, namely the nanocone array. The nanocone array prepared by the invention has the advantages of extremely low turn-on field and extremely low threshold field; and the method is used for the field of nanometer materials.

The invention relates to N-doped SiC nanoneedle and application thereof. The doping amount of N atoms in the N-doped SiC nanoneedle is 2-10at%. The length of the nanoneedle is 1-100 micrometers. The diameter of the tip of the needle is 50-500 nm. The N-doped SiC nanoneedle serves as a flexible field emitting cathode material. The N-doped SiC nanoneedle flexible field emitting cathode material has the low opening electric field at different temperatures and has the stable electron emission characteristics at high temperatures.

The invention provides a graphene field emission cathode, which comprises a conductive substrate and a graphene/nano-metal composite layer combined on one surface of the conductive substrate, whereinthe graphene/nano-metal composite layer comprises a graphene layer and a nano-metal material layer combined on the graphene layer, the nano-metal material layer is arranged on the surface, which deviates from the conductive substrate, of the graphene layer, the metal-nano material layer is composed of metal nanoparticles, and the work function of the metal nanoparticles is less than or equal to 4.5eV. By arranging the low-work-function metal nanoparticles on the surface of graphene, the starting electric field of the graphene cathode is remarkably reduced, the field emission current density isimproved, and the current emission stability of the graphene field emission cathode is improved.

The invention relates to nanowire material applied in field emission material, particularly relates to application of a B-doped SiC nanowire in field emission cathode material, and belongs to the technical field of nano-material. The B-doped SiC nanowire is a field emission cathode. An emission electric field is formed between the field emission cathode and a field emission anode in voltage applying. The turn-on field intensity of the field emission cathode is 0.6-1.05V/muA when emission current density is 10muA/cm2 under the condition of vacuum. The B-doped SiC nanowire field emission cathode material is convenient to process, great in cost controllability, stable in performance and high in flexibility; the material has low turn-on electric field after different bending frequency and basically remains unchanged and maintains high electron emission stability; the material has low turn-on electric field under different bending states and basically remains unchanged and maintains high electron emission stability; and the material has low turn-on electric field under different temperature and maintains high electron emission stability.

The invention discloses a composite nano cold cathode structure with high stability electron emission and a preparation method. The composite nano cold cathode structure comprises a substrate, a low-dimensional nano cold cathode vertically prepared on the substrate, a two-dimensional thin film material covering the tip of the low-dimensional nano cold cathode and a support structure used for regulating the geometric curvature of the tip of the two-dimensional thin film material. The structure has the advantage that a clean emission surface is obtained by using the surface without a dangling bond structure of the two-dimensional thin film material. In addition, the transport process of emitted electrons can be controlled through regulating the geometric curvature of the tip of the two-dimensional thin film material, thereby enabling the emitted electrons to become hot electrons with high energy, and thus having a lower turn-on electric field. The cleaner surface and the lower surface barrier enable the composite low-dimensional nano cold cathode to achieve high stability electron emission.

The invention discloses a carbon nanotube field emission cathode. The cathode comprises: a conductive substrate; a carbon nanotube formed on the conductive substrate; and molybdenum sulfide nanoparticles bonded on the surface of the carbon nanotube. The preparation method of the carbon nanotube field emission cathode comprises the following steps: providing a carbon nanotube and enabling the surface of the carbon nanotube to have carboxylic acid groups through a surface treatment process; dissolving the carbon nanotube, a molybdenum source, a sulfur source and a surfactant in a solvent, carrying out ultrasonic dispersion, and then carrying out a heating reaction to obtain a carbon nanotube of which the surface is combined with molybdenum sulfide nanoparticles; placing the carbon nanotube in a ball milling tank, adding an organic solvent and a ball milling auxiliary agent, and carrying out ball milling to obtain carbon nanotube slurry; printing the carbon nanotube slurry on a conductive substrate through a screen printing process; and heating and curing the conductive substrate, and carrying out annealing treatment to prepare the carbon nanotube field emission cathode. The carbon nanotube field emission cathode provided by the invention can reduce the starting electric field and improve the emission stability.