JP2009026594A - Electron source, manufacturing method thereof, and discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: an electron source that achieves electron emission at low voltage, stable operation and high reliability; a method for manufacturing the electron source; and a discharge device such as a cold cathode discharge lamp using the electron source. <P>SOLUTION: An electron source 1 has a substrate 2, an aggregate of diamond crystal particles 3 that is formed on the substrate 2, and platinum particles 4 formed on the top surface of the diamond crystal particles 3. The electron source 1 is used for a discharge device such as a cold cathode discharge lamp. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electron source, a method for manufacturing the electron source, and a discharge device using the electron source.

  As an electron source for emitting electrons into a discharge gas or vacuum, a thermionic source and a cold electron source are known. In particular, a cold electron source is expected to be realized as a driving force for a breakthrough of a wide range of electronic devices, because standby power is not required and electrons can be emitted immediately, heating means are unnecessary, and miniaturization can be expected. . However, it cannot be said that a high-performance cold electron source sufficient to replace the heating electron source has been obtained so far due to the instability of the surface accompanying the lowering of temperature.

  Under such circumstances, cold electron sources using various carbon-based materials have attracted attention and are being actively developed. This is because the property that no oxide film is formed on the carbon surface is effective in maintaining stable characteristics at room temperature. Furthermore, a cold electron source using diamond, which is a form of carbon, has a negative electron affinity characteristic based on its wide bandgap characteristics, so the surface electron barrier is small, and stable electron emission that is not affected by ambient fluctuations is expected. (See Patent Document 1).

JP 2001-283715 A

  However, although the electron affinity of diamond is certainly small, it is known that the terminal state of the diamond surface is important in order to have a negative electron affinity that releases electrons very easily. Specifically, when hydrogen is terminated on the surface, a negative electron affinity can be obtained. However, if this hydrogen termination is lost, the electron affinity is increased, so that the electron affinity becomes positive. For this reason, when charged particles collide with the hydrogen terminal of the diamond surface and the hydrogen terminal is lost, the negative electron affinity of the diamond is lost and the electron emission characteristics of the cold electron source are significantly deteriorated. It was.

  The present invention has been made in view of the above, and an object of the present invention is to provide an electron source having excellent electron emission characteristics, a method for producing the electron source, and a discharge device using the electron source.

  In order to solve the above-described problems and achieve the object, the present invention provides a substrate, an aggregate of diamond crystal particles formed on the substrate, and platinum group fine particles formed on the surface of the diamond crystal particles. And comprising.

  In addition, the present invention includes a mixing step of mixing platinum colloid or an aqueous solution of platinic acid and diamond crystal particles, and a heat treatment step of heat-treating the mixture in the mixing step in a hydrogen atmosphere. To do.

  According to the present invention, it is possible to continue to emit electrons at a low applied voltage, and there is an effect that the operation is stable and the reliability is high.

  Exemplary embodiments of an electron source, an electron source manufacturing method, and a discharge device according to the present invention will be explained below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an electron source according to a first embodiment. The electron source 1 includes a substrate 2, diamond crystal fine particles (NPD) 3, and platinum fine particles (Pt) 4.

  The substrate 2 holds an aggregate of diamond crystal fine particles 3. Since a voltage is applied to the substrate 2, any material can be used as long as it has conductivity. In this embodiment, a metal such as Ni is used for the surface of the substrate 2.

  The diamond crystal particles 3 are crystal diamond particles formed as an aggregate on the substrate 2, and the surface thereof is hydrogen-terminated. The size of the diamond crystal fine particles 3 is preferably on the order of submicron nanometers and an average of 200 nm or less. In the present embodiment, the average is 50 nm. When a voltage is applied to the electron source 1, the diamond crystal particles 3 emit electrons from the surface.

  The platinum fine particles 4 are platinum fine particles carried on the surface of the diamond crystal fine particles 3. The platinum fine particles 4 are finely divided in order to terminate the surface of the diamond crystal fine particles 3 with hydrogen. The size of the platinum fine particles 4 is preferably a few nm to 10 nm level, and is preferably at least smaller than the diamond crystal fine particles 3.

  Here, the reason for the difference in electron emission characteristics between the case where the surface of the diamond crystal fine particle is hydrogen-terminated and the case where the surface is not hydrogen-terminated will be described. FIG. 2 is a drawing for explaining the surface structure of the diamond crystal fine particles 3. Since diamond is a semiconductor having a very large band gap of 5.5 eV, the energy level of the conduction band is very high. For this reason, even if the surface of the diamond crystal fine particles 3 is not hydrogen-terminated, the electron affinity for vacuum is small. Furthermore, when the surface is hydrogen-terminated, a negative affinity state is realized in which the energy level of electrons in vacuum is lower than the energy level of the conduction band. In this state, since the electron emission barrier from the diamond crystal fine particles 3 is small, electrons are easily emitted, and an improvement in electron emission characteristics can be expected.

  The carbon-hydrogen bond at the hydrogen-terminated portion of the surface of the diamond crystal fine particle 3 is stable until the temperature reaches 700 ° C. Compared with the bond between other atoms, for example, the bond between silicon and hydrogen. , Its stability is very high. However, when used as an electron source, a negative voltage is applied to the diamond crystal fine particles, so that positively charged ion particles in the atmosphere cannot avoid collision with the hydrogen termination on the surface. There is a possibility that hydrogen is desorbed by (sputtering with positive charged ion particles). The diamond crystal fine particles 3 supporting the platinum fine particles 4 according to the present embodiment can solve this problem.

FIG. 3 is a view for explaining the reaction on the surface of the diamond crystal fine particles 3 carrying the platinum fine particles 4 according to the present embodiment. In the present embodiment, the platinum fine particles 4 are supported on the diamond crystal fine particles 3 to adsorb and decompose hydrogen H ₂ in the atmosphere on the surfaces of the platinum fine particles 4 to generate atomic hydrogen H. The atomic hydrogen H thus produced can be supplied to the surface of the diamond crystal fine particles 3. Such decomposition of hydrogen by the platinum fine particles 4 and supply of the decomposed atomic hydrogen to other parts are known as a spillover phenomenon.

  Therefore, by utilizing this spillover phenomenon, the surface of the diamond crystal fine particles 3 is replenished with active atomic hydrogen H, and the surface portion that is not terminated due to the collision of the charged particles is returned to the hydrogen-terminated state again. Can do. Since the generation of the atomic hydrogen H is performed by the platinum fine particles 4, as described above, the platinum fine particles 4 are desirably atomized, and the diameter is desirably several nm to 10 nm. Moreover, it is desirable to make it at least smaller than diamond particles.

  As described above, in the electron source 1, sputtering of the surface of the diamond crystal fine particles 3 due to collision of positively charged charged particles cannot be avoided. The fine particles 4 can be re-adsorbed and terminated on the surface as a catalyst, and the electron emission characteristics of the electron source 1 are maintained.

  FIG. 4 is a diagram for explaining the charge transfer in the diamond crystal particles 3 carrying the platinum particles 4. The diamond crystal fine particles 3 are terminated with hydrogen to generate a p-type conductive layer on the surface. In the present embodiment, the crystalline diamond is made into fine particles, and the surface thereof is hydrogen-terminated, and then the crystalline diamond is laminated on the substrate 2 as an aggregate. For this reason, a conduction path is formed on the surface of the diamond crystal fine particles 3, and conduction in the depth direction, which cannot be obtained with a bulk crystal, can be obtained.

  Therefore, the electron source 1 has a laminated structure using undoped fine particles not doped with B (boron) or the like, but the electron conduction between the portion present on the most surface side of the diamond crystal fine particles 3 and the substrate 2. Can be obtained. Of course, it does not deny that the diamond crystal fine particles 3 are formed as a single layer or discretely and the formed product is used as a part of the electron source.

  Further, diamond crystals and platinum are finely divided and then laminated on the substrate 2 as an aggregate, whereby a structure composed of the diamond crystal fine particles 3 and the platinum fine particles 4 is formed on the substrate 2 several times. For this reason, even if the diamond crystal fine particles 3 carrying the platinum fine particles 4 existing on the most surface side are sputtered by the positively charged ion particles, the diamond crystal fine particles 3 carrying another platinum fine particles 4 having the same structure are surfaced. Therefore, the electron emission characteristics of the electron source 1 can be maintained.

  Further, when the diamond crystal fine particles 3 are made fine, the total surface area can be increased compared to the same amount of diamond crystals, and even if the hydrogen termination of the part from which electrons are emitted is damaged by ending the entire surface with hydrogen, It can be replenished with hydrogen terminating in other surface parts.

(Production method)
A method for manufacturing the electron source according to this embodiment will be described. First, the crystal diamond produced by the high-pressure synthesis method is made into fine particles by the pulverization method, and the diamond crystal fine particles 3 are produced. In the present embodiment, the average size of the fine particles is 50 nm. By proceeding the pulverization, the crystal defects that have entered during the high-pressure synthesis are removed, and as a result, high-quality diamond crystal fine particles 3 are obtained. And after grinding | pulverization, it processes using the heated nitric acid of 250 degreeC or more, and removes the impurity and graphite component which have adhered to the surface. The surface of the diamond crystal fine particles 3 in this state is in an oxidized state, and the surface thereof can be hydrogen-terminated by performing a heat treatment in a hydrogen atmosphere or a heat treatment in a hydrogen plasma atmosphere. The surface hydrogen termination in this production method is simultaneously performed in the step of supporting the platinum fine particles 4 on the surface of the diamond crystal fine particles 3 described below.

Next, platinum fine particles 4 are supported on the surface of the diamond crystal fine particles 3. FIG. 5 is a diagram for explaining a process of supporting the platinum fine particles 4 on the surface of the diamond crystal fine particles 3. First, the diamond crystal fine particles 3 are impregnated in a tetraammine platinum chloride (Pt (NH ₃ ) 4 Cl ₂ ) solution, and then the diamond crystal fine particles 3 are solidified with tetraammine platinum chloride. Next, the diamond crystal fine particles 3 in which tetraammineplatinum chloride is dried are heated from room temperature in a hydrogen gas atmosphere and heat-treated. In this heat treatment step, the tetraammine platinum chloride compound is decomposed to produce ammonium chloride and the like, and the platinum fine particles 4 are supported on the surface of the diamond crystal fine particles 3. Moreover, the surface of the diamond crystal particle 3 can be hydrogen-terminated by this heat treatment step.

  The platinum colloid solution is impregnated with the diamond crystal fine particles 3 instead of tetraammine platinum chloride, and then the diamond crystal fine particles 3 are solidified with platinum, followed by heat treatment, so that the platinum fine particles 4 are converted into the surface of the diamond crystal fine particles 3. It is also possible to carry it.

  FIG. 6 is a photograph of the diamond crystal fine particles 3 carrying the platinum fine particles 4 produced by the above method observed with a TEM (transmission electron microscope). In the photograph, particles that appear black are platinum fine particles 4, and large particles that appear gray with platinum fine particles 4 attached are diamond crystal fine particles 3. As is apparent from the photograph, the platinum fine particles 4 are supported on the diamond crystal fine particles 3. The amount of platinum fine particles 4 supported on the diamond crystal fine particles 3 at this time is about 40% by weight with respect to the diamond crystal fine particles 3. Of course, the carrying amount is not limited to this value. Moreover, it can be seen from the photograph that the platinum fine particles 4 become clearer and the agglomeration progresses as the heat treatment temperature increases to 300 ° C., 500 ° C., and 700 ° C.

  Most of the tetraammineplatinum chloride compound is decomposed at a heat treatment temperature of 500 ° C., and at that time, the platinum fine particles 4 are in a state having catalytic ability. However, in order to ensure the hydrogen termination on the surface of the diamond crystal fine particles 3, it is necessary to raise the temperature to 700 ° C. or higher and to perform heat treatment. On the other hand, if the temperature is too high, the diamond crystal particles 3 themselves start to decompose, and further, the platinum particles 4 aggregate to increase the particle size.

  Thus, by performing heat treatment in the range of 700 ° C. to 800 ° C., the electron source 1 having excellent electron emission characteristics in which the surface of the diamond crystal fine particles 3 is sufficiently hydrogen-terminated can be produced.

  Next, diamond crystal particles 3 carrying platinum particles 4 are formed on the substrate 2. In the present embodiment, a metal such as Ni that easily forms carbide is selected for the surface layer of the substrate 2, the diamond crystal fine particles 3 are rubbed on the substrate 2, and then heat treatment or the like is performed. Is completed. By this method, the contact between the diamond crystal particles 3 and the substrate 2 can be ensured. The formation method on the substrate is not limited to this, and in order to ensure contact between the substrate surface and the fine particles, the substrate surface is carbonized in advance and then fine particles are formed, or heat treatment is performed in a hydrogen atmosphere after the fine particles are formed. Good. Further, a binder may be mixed into the particles in order to give strength as a film. As the binder material, a polymer such as an acrylic resin can be used, and this can be mixed with fine particles to form a coating film, which can be heat treated in a hydrogen atmosphere to leave the carbon component between the particles.

  In addition, by using diamond crystals that are fine particles, it can be applied to electrodes with complex shapes and substrates with low heat resistance that could not be formed without CVD (chemical vapor deposition). Diamond crystal fine particles can be formed by spin coating, rubbing or the like, and can be applied to an electron source.

  FIG. 7 is a graph showing the photoelectron emission characteristics of various conventional materials, and FIG. 8 is a diamond carrying platinum fine particles produced by various conventional materials and the method of producing an electron source according to the present embodiment. It is a graph which shows the photoelectron emission characteristic of the electron source which has a crystal particle. In both figures, the horizontal axis represents the excitation light energy, and the vertical axis represents the amount of photoelectrons emitted.

  Here, A in the figure is a stage where the diamond crystal fine particles having a particle diameter of 150 nm are acid-treated, and impurities and graphite components adhering to the surface are removed. Further, B in the figure is obtained by heat-treating the diamond crystal particles of A at 750 ° C. in a hydrogen atmosphere and terminating the surface with hydrogen. In the figure, C is a diamond crystal fine particle having a particle diameter of 50 nm, acid-treated to remove impurities and graphite components adhering to the surface, and then heat-treated at 750 ° C. in a hydrogen atmosphere. Is hydrogen-terminated.

  In addition, D in the figure is a polycrystalline diamond thin film doped with boron and produced by chemical vapor deposition. In addition, E in the drawing is diamond crystal fine particles at the stage where platinum colloid is dried on the surface. Moreover, F in the figure is a Ni substrate on which nothing is formed on the surface.

  G, H, and I in the figure are the heat treatment temperatures in a hydrogen gas atmosphere for supporting the platinum fine particles on the diamond crystal fine particles, respectively, using the method for manufacturing the electron source according to the present embodiment described above. These are diamond crystal fine particles (electron source) having a particle diameter of 50 nm and carrying platinum fine particles at 300 ° C., 500 ° C., and 700 ° C.

  As can be seen from FIG. 7, B and C whose surfaces of the diamond crystal fine particles are hydrogen-terminated begin to exhibit photoelectron emission from the stage where the excitation light energy is 5 eV or less, and have extremely high photoelectron emission characteristics. These photoelectron emission characteristics exceed D, which is a polycrystalline diamond thin film doped with boron. On the other hand, the diamond crystal fine particles whose surface is only acid-treated and not hydrogen-terminated do not emit photoelectrons when the excitation light energy is 7 eV or less.

  Further, as can be seen from FIG. 8, among diamond crystal fine particles carrying platinum fine particles, G and H heat-treated at 300 ° C. and 500 ° C. show only very weak photoelectron emission. On the other hand, I heat-treated at 700 ° C. shows higher photoelectron emission characteristics than D, which is a polycrystalline diamond thin film doped with boron, and diamond crystal fine particles not carrying platinum fine particles heat-treated at 750 ° C. The photoelectron emission characteristic of the same order as that of a certain C is shown.

  FIG. 9 is a graph comparing photoelectron emission amounts when the excitation light energy is 7 eV for each material from the graphs showing the photoelectron emission characteristics of FIGS. 7 and 8. Although overlapping with the above description, as can be seen from the figure, the surface of the diamond crystal particles that has been subjected to acid treatment only and not hydrogen-terminated has only a very small amount of photoelectrons that do not reach F, which is a simple Ni substrate. Not released. On the other hand, diamond crystal fine particles I carrying platinum fine particles heat-treated at 700 ° C. are larger than D, which is a polycrystalline diamond thin film doped with boron, and diamond crystal fine particles not carrying platinum fine particles heat-treated at 750 ° C. The amount of photoelectrons is comparable to that of C.

  FIG. 10 is an FT-IR (Fourier transform infrared spectroscopy) spectrum of the surface of diamond crystal fine particles not supporting conventional platinum fine particles. In addition, A and B in the figure are the same as A and B in FIG. 7 and FIG. As is apparent from the figure, the diamond crystal fine particles whose surface is only acid-treated and not hydrogen-terminated, A is derived from a modification group bond containing oxygen (O), which is considered to be derived from acid treatment, and from the etching solution water. The surface is occupied by oxygen-hydrogen (OH) bonds considered to be Here, when A is subjected to a high-temperature hydrogen heat treatment at 750 ° C., these bonds on the surface disappear, and like B, the surface is replaced with a clean carbon-hydrogen (CH) bond, resulting in a hydrogen-terminated state. Recognize.

  FIG. 11 is an FT-IR (Fourier transform infrared spectroscopy) spectrum of the surface of the diamond crystal particle carrying the platinum particle of the present embodiment. In addition, GI in a figure is the same as GI in FIG. 8 and FIG. As is apparent from the figure, even with diamond crystal particles supporting platinum particles, the surface of the diamond crystal particles is G (treatment temperature 300 ° C.) or H (treatment temperature 500 ° C.) where the heat treatment temperature in the hydrogen gas atmosphere is low. There is not much change from the state during acid treatment. For this reason, it has the modification group coupling | bonding containing oxygen (O) considered that acid treatment originates, and the oxygen-hydrogen (OH) coupling | bonding considered that it originates in the water of etching liquid. In contrast, in the case of I heat-treated at 700 ° C. in a hydrogen gas atmosphere, these bonds on the surface of the diamond crystal fine particles disappear or become extremely weak, and instead a strong carbon-hydrogen (CH) bond is formed. It turns out that it is in a hydrogen termination state.

  FIG. 12 is a diagram showing the results of measuring the relationship between the discharge start voltage and the PD product of the electron source 1 of the present embodiment. In the figure, the horizontal axis represents the PD product, and the vertical axis represents the discharge start voltage. In addition, this measurement is performed in argon gas. As can be seen from the figure, the reduction of the discharge voltage can be confirmed over a wide range.

  In the present embodiment, the fine particles supported on the surface of the diamond crystal fine particles are platinum, but other substances capable of generating a spillover phenomenon such as other platinum groups may be used.

  Further, in the present embodiment, the crystal diamond produced by the high-pressure synthesis method is finely divided by the pulverization method to produce the diamond crystal fine particles, but the polycrystalline diamond synthesized by the CVD method is finely divided by the pulverization method, Diamond crystal fine particles may be produced.

  As described above, according to the electron source according to the first embodiment, even if the hydrogen termination is damaged by sputtering on the surface of the diamond crystal fine particles supporting platinum fine particles, the action of the platinum fine particles supported on the diamond crystal fine particles is effective. The once desorbed hydrogen can be terminated again on the surface, and the electron emission characteristics of the electron source are maintained, allowing electrons to continue to be emitted at a low applied voltage, realizing high operational stability and reliability. It becomes possible to do.

  Furthermore, according to the electron source according to the first embodiment, since the hydrogen termination portion existing on the surface of the diamond crystal fine particles supporting the platinum fine particles can conduct electrons, the resistance of the electron source is reduced, Electrons can be emitted with a low applied voltage.

  Furthermore, according to the electron source according to the first embodiment, since the diamond crystal carrying the platinum fine particles is finely divided into an aggregate, the diamond crystal fine particles carrying the platinum fine particles on the surface of the electron source are sputtered. Even so, the diamond crystal particles carrying other platinum particles having the same structure are exposed on the surface, and the electron emission characteristics of the electron source are maintained, so it is possible to continue emitting electrons at a low applied voltage, High operational stability and reliability can be realized.

  Further, according to the electron source according to the first embodiment, since the diamond crystal carrying the platinum fine particles is finely divided into an aggregate, the total surface area is increased, and the hydrogen termination of the electron emission portion is damaged. However, hydrogen terminated on the other surface can be replenished, and the electron emission characteristics of the electron source are maintained, so that electrons can be continuously emitted at a low applied voltage, and high operational stability and reliability are achieved. Can be realized.

(Second Embodiment)
The second embodiment is different from the first embodiment in that impurities are added to the diamond crystal fine particles. A second embodiment will be described with reference to the accompanying drawings.

  FIG. 13 is a diagram illustrating a configuration of an electron source according to the second embodiment. The electron source 5 includes a substrate 2, impurity-doped diamond crystal particles 6, and platinum particles 4. Here, since the substrate 2 and the platinum fine particles 4 are the same as those described in the first embodiment, the description is omitted with reference to the above description.

  Impurity-added diamond crystal particles 6 are doped (doped) with diamond crystal particles. As the types of impurities, group III elements such as B (boron) and group V elements such as P (phosphorus) and N (nitrogen) can be used. The impurity-added diamond crystal fine particles 6 have p-type conductivity when B is doped at a high concentration, and therefore can be used for a secondary electron source such as a discharge electron source, and when P or N is doped at a high concentration. Since it has n-type conduction, it can be used as a primary electron source.

  FIG. 14 is a diagram for explaining the charge transfer in the impurity-added diamond crystal particles 6 carrying the platinum particles 4. The impurity-doped diamond crystal fine particles 6 are formed not only with p-type conduction paths generated on the surface thereof, but also with p-type or n-type conduction paths generated by carriers existing therein, so that electrons are more conductive. It becomes easy to do. As a result, the electron source 5 has a lower resistance.

  As described above, according to the electron source according to the second embodiment, the hydrogen terminal portion existing on the surface of the impurity-added diamond crystal fine particles supporting the platinum fine particles not only conducts electrons, but also exists in the interior thereof. Since carriers can also conduct electrons, an electron source with lower resistance can be manufactured.

(Third embodiment)
The third embodiment is different from the first embodiment in that conductive fibers such as carbon nanotubes exist between diamond crystal particles. A third embodiment will be described with reference to the accompanying drawings.

  FIG. 15 is a view of a part of the electron source according to the third embodiment as viewed from above. The electron source 7 includes a substrate 2 (not shown), diamond crystal particles 3, platinum particles 4, and carbon nanotubes (CNT) 8. Here, since the substrate 2, the diamond crystal fine particles 3, and the platinum fine particles 4 are the same as those described in the first embodiment, the description is omitted with reference to the above description.

  The carbon nanotube 8 is a carbon crystal in the shape of a cylinder having a diameter of a nanometer unit and a length of about several tens of μm, and has conductivity. The carbon nanotubes 8 exist between the diamond crystal particles 3 while being entangled with each other, and form a complicated three-dimensional structure together with the diamond crystal particles 3. Note that other conductive fibers may be added instead of the carbon nanotubes 8.

  In the electron source 7, not only the p-type conduction path generated on the surface of the diamond crystal fine particle 3 but also the conduction path formed by the carbon nanotubes 8 is formed, so that electrons are more easily conducted. As a result, the electron source 7 has a lower resistance. Furthermore, since the aggregate of the diamond crystal fine particles 3 and the carbon nanotubes 8 formed on the substrate 2 are intertwined in a complicated manner, the strength is improved as compared with the aggregate of the diamond crystal fine particles 3 alone.

(Production method)
A method for manufacturing the electron source according to this embodiment will be described. First, the electron source manufacturing method according to the first embodiment is executed halfway to form the diamond crystal particles 3 that carry the platinum particles 4 and whose surfaces are hydrogen-terminated.

  Next, an organic solvent or a polymer is added to the diamond crystal particles 3 supporting the platinum particles 4 and kneaded to form a slurry. Then, carbon nanotubes 8 are added and further kneaded.

  At this time, the carbon nanotube 8 to be used is preferably a multi-layer type rather than a single-wall type. This is because the multi-layer type exhibits metallic conduction, so that the conductivity including the diamond crystal particles 3 supporting the platinum particles 4 can be improved.

  Further, the carbon nanotube 8 is preferably bent or wound rather than a straight one having no structural defect. This is because the carbon nanotubes 8 are entangled with each other in the kneading process, and as a result, a complicated entangled three-dimensional structure is formed between the diamond crystal particles 3 supporting the platinum fine particles 4 and the structure is stabilized. It is.

  Next, the diamond crystal fine particles 3 supporting the platinum fine particles 4 and the carbon nanotubes 8 are rubbed onto the substrate 2 and then subjected to heat treatment to remove the organic solvent. The electron source 7 is completed. In order to prevent oxidation of the diamond crystal fine particles 3, it is desirable to perform the heat treatment in a hydrogen atmosphere. The formation method on the substrate is not limited to this, and in order to ensure contact between the substrate surface and the fine particles, the substrate surface is carbonized in advance and then fine particles are formed, or heat treatment is performed in a hydrogen atmosphere after the fine particles are formed. Good. Further, a binder may be mixed into the particles in order to give strength as a film. As the binder material, a polymer such as an acrylic resin can be used, and this can be mixed with fine particles to form a coating film, which can be heat treated in a hydrogen atmosphere to leave the carbon component between the particles.

  As described above, according to the electron source according to the third embodiment, the hydrogen terminal portion existing on the surface of the diamond crystal fine particles supporting the platinum fine particles not only conducts electrons but also exists between the diamond crystal fine particles. Since the carbon nanotube that conducts can also conduct electrons, an electron source with lower resistance can be produced.

  Furthermore, according to the electron source according to the third embodiment, since the aggregate in which the diamond crystal particles carrying the platinum particles and the carbon nanotubes are intricately formed, the structure can be stabilized, The strength can be improved as compared with the aggregate formed of the diamond crystal fine particles alone.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to the accompanying drawings. In the present embodiment, the electron source according to the first embodiment is applied to a cold cathode discharge lamp. FIG. 16 is a side sectional view showing an example of a cold cathode discharge lamp to which the electron source described in the first embodiment is applied.

  The cold cathode discharge lamp 10 encloses a glass tube 11 with a small amount of mercury, a small amount of hydrogen (or hydrocarbon), and inert gases such as argon (Ar) and neon (Ne). Further, a phosphor 12 that generates visible light by ultraviolet rays is further formed. In addition, electron sources 13 are provided at both ends of the glass tube 11, and lead wires 14 for applying a voltage from the outside are connected to one end of each electron source 13.

  Here, the electron source 13 is the one in which the electron source of the first embodiment is formed in a cup shape, a Ni substrate is formed in a cup shape, and an aggregate of diamond crystal particles carrying platinum particles on the inner surface thereof. Has a structure in which multiple coatings are applied. In order to ensure contact between the substrate surface and the fine particles, the substrate surface may be carbonized in advance and then fine particles may be formed, or heat treatment may be performed in a hydrogen atmosphere after the fine particles are formed. Further, a binder may be mixed into the particles in order to give strength as a film. As the binder material, a polymer such as an acrylic resin can be used, and this can be mixed with fine particles to form a coating film, which can be heat treated in a hydrogen atmosphere to leave the carbon component between the particles.

  When a voltage is applied to the electron source 13 from the outside via the lead-in wire 14, discharge is started. When the discharge is started, the ionized sealed gas collides with the diamond crystal particles carrying the platinum fine particles forming the discharge surface of the electron source 13, and electrons are emitted from the diamond crystal fine particles carrying the platinum fine particles by secondary electron emission. Released. Furthermore, a cycle occurs in which the electrons are accelerated and collide with the atoms of the sealed gas to be ionized. That is, when such a cycle occurs, the voltage required for maintaining the discharge is lower than the voltage at the start of discharge.

  Here, since the surface of the diamond crystal fine particles carrying the platinum fine particles of the electron source 13 is hydrogen-terminated, a negative affinity state can be maintained. Therefore, the electron source 13 can emit electrons with a low applied voltage, and the discharge start voltage and the discharge sustain voltage can be reduced.

The encapsulated mercury is excited by the collision of electrons, ionized or excited encapsulated argon and neon, and generates ultraviolet rays. When the ultraviolet rays collide with the phosphor 12, the phosphor 12 is excited and visible light is generated.

  While the electron source 13 is discharging, the ionized argon and neon collide with diamond crystal particles carrying the platinum particles of the electron source 13. As a result, the surface of the diamond crystal particle carrying the platinum particle is sputtered, the hydrogen termination on the surface is damaged, and the electron emission characteristics of the electron source 13 may be deteriorated as it is. However, since the hydrogen once desorbed and a minute amount of hydrogen (or hydrocarbon) sealed in the glass tube 11 can be re-adsorbed and terminated on the surface of the diamond crystal fine particle using the platinum fine particle as a catalyst. The electron emission characteristics of the electron source 13 are maintained. Thereby, the cold cathode discharge lamp 10 can achieve power saving, high discharge efficiency, and long life.

  Further, diamond crystals and platinum are atomized and then laminated on the Ni substrate as an aggregate, whereby a structure of diamond crystal particles and platinum particles is formed on the Ni substrate. For this reason, even if diamond crystal particles carrying platinum fine particles existing on the surface are sputtered by positive charged ion particles, diamond crystal fine particles carrying other platinum fine particles having the same structure are exposed on the surface, so that the electron source The 13 electron emission characteristics are maintained. Thereby, the cold cathode discharge lamp 10 can achieve power saving, high discharge efficiency, and long life.

  As described above, according to the cold cathode discharge lamp according to the fourth embodiment, even if the hydrogen termination is damaged by sputtering on the surface of the diamond crystal particles carrying the platinum particles, the platinum particles carried on the diamond crystal particles Due to the action, hydrogen contained in the discharge gas in the cold cathode discharge lamp can be terminated on the surface, and the electron emission characteristics can be maintained, so that power saving, high discharge efficiency, and long life can be realized. Is possible.

  Furthermore, according to the cold cathode discharge lamp according to the fourth embodiment, the aggregate of the diamond crystal particles supporting the platinum fine particles of the electron source is formed in multiple layers. Even if the surface of the diamond crystal particle carrying the fine particles is sputtered, the diamond crystal particle carrying the platinum fine particles having the same structure can always discharge electrons and maintain the electron emission characteristics. High discharge efficiency and long life can be realized.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to the accompanying drawings. In the present embodiment, the electron source according to the first embodiment is applied to a magnetron. FIG. 17 is a side sectional view showing an example of a magnetron to which the electron source described in the first embodiment is applied.

  Of the magnetron 20, the filament terminal 21 is connected to a high-frequency inverter power supply (not shown), and a power supply voltage for the filament is supplied from the high-frequency inverter power supply. The filament terminal 21 is connected to the coil 23 through a capacitor 22. The coil 23 forms a filter circuit together with the capacitor 22 so that noise generated by the magnetron 20 does not leak outside through the filament terminal 21.

  The coil 23 is connected to filament support bars 24a and 24b. The filament support bars 24a and 24b are hermetically sealed with a stem ceramic 25, and a filament 26 is connected to the upper ends of the filament support bars 24a and 24b.

  Here, the filament 26 is obtained by forming the electron source according to the first embodiment into a filament shape, and a plurality of aggregates of diamond crystal particles supporting platinum particles on the surface of a metal such as tungsten. The structure is applied and fixed.

  A cylindrical anode 27 is provided outside the filament 26, and a space surrounded by the anode 27 is partitioned by a plurality of vanes 28 extending radially from the anode 27 in the direction of the filament 26 to form a resonator. Magnets 29a and 29b that apply a magnetic field in the vertical direction to the resonator are disposed above and below the resonator. A plurality of cooling fins 30 for releasing the heat of the anode 27 are provided around the anode 27 at intervals in the vertical direction. The cooling fins 30, the anodes 27, etc. are accommodated in a metal container 31. The metal container 31 forms a magnetic path for the magnets 29a and 29b.

  With the configuration described above, when a power supply voltage is applied to the filament terminal 21, electrons are generated from the filament 26 and move toward the anode 27. At that time, a high frequency signal is generated by the action of a resonator or the like located between the anode 27 and the filament 26. This high frequency signal is taken out by the antenna lead 32.

  Here, the power supply voltage applied to the filament 26 can maintain a negative affinity state because the surface of the diamond crystal fine particles of the filament 26 is hydrogen-terminated. For this reason, compared with the conventional filament, an equivalent amount of electrons can be generated at a lower voltage. Therefore, the operating temperature of the magnetron 20 is lowered, and the lifetime is longer than that of the conventional product.

  Further, when a voltage is applied to the filament 26 to generate electrons, the substance remaining in the metal container 31 is ionized and collides with the diamond crystal particles of the filament 26. As a result, the surface of the diamond crystal fine particles is sputtered, the hydrogen termination on the surface is damaged, and there is a possibility that the electron emission characteristics of the filament 26 are deteriorated as it is. However, once desorbed hydrogen can be re-adsorbed and terminated on the surface of the diamond crystal fine particles using platinum fine particles as a catalyst, the electron emission characteristics of the filament 26 can maintain the initial characteristics. Thereby, the magnetron 20 can realize power saving, high discharge efficiency, and long life.

  Further, diamond crystals and platinum are atomized and then laminated on a metal such as tungsten as an aggregate, whereby a structure composed of diamond crystal particles and platinum particles is formed on the substrate. For this reason, even if the diamond crystal particles carrying the platinum fine particles existing on the surface are sputtered by the positive charged ion particles, the diamond crystal fine particles carrying the other platinum fine particles having the same structure are exposed on the surface. The electron emission characteristics of the above are maintained. Thereby, the magnetron 20 can realize power saving, high discharge efficiency, and long life.

  As described above, according to the magnetron according to the fifth embodiment, even if the hydrogen termination is damaged by sputtering on the surface of the diamond crystal fine particles supporting the platinum fine particles of the filament, the action of the platinum fine particles supported on the diamond crystal fine particles. Thus, hydrogen once desorbed in the magnetron can be terminated again on the surface, and the electron emission characteristics can be maintained. Therefore, it is possible to realize power saving, high discharge efficiency, and long life.

  Furthermore, according to the magnetron according to the fifth embodiment, since the aggregate of diamond crystal particles supporting the platinum fine particles of the filament is formed in multiple layers, the platinum particles on the surface of the filament are supported by the electron generation operation. Even when the surface of the diamond crystal particles to be sputtered, the diamond crystal particles that carry platinum particles of the same structure can always generate electrons and maintain the electron emission characteristics, thus saving power and high discharge efficiency. It is possible to realize a long life.

(Sixth embodiment)
Next, a sixth embodiment will be described with reference to the accompanying drawings. In the present embodiment, the electron source according to the first embodiment is applied to an open X-ray tube. FIG. 18 is a side sectional view showing an example of an open X-ray tube to which the electron source described in the first embodiment is applied.

  The open X-ray tube 40 is composed of a cathode part 41 (lower part), an anode part 42 (middle part), and a target part 43 (upper part), and each part is vacuum-tightly connected to each other by an O-ring. A vacuum chamber 44 is formed in two stages by a rotary pump (not shown). When performing maintenance, the open X-ray tube 40 can release the cathode part 41, the anode part 42, and the target part 43, and replace components such as the filament 45 therein. In the cathode portion 41, a high voltage cable is inserted into the high voltage cable insertion port 46, and a negative high voltage is applied to the electrode of the Wehnelt 47 and the filament 45.

  Here, the filament 45 is obtained by forming the electron source according to the first embodiment into a filament shape, and a plurality of aggregates of diamond crystal particles supporting platinum particles on the surface of a metal such as tungsten. The structure is applied and fixed. Furthermore, a very small amount of hydrogen (or hydrocarbon) is enclosed in the vacuum chamber 44.

  The anode part 42, the target part 43, and the exterior of the vacuum chamber 44 are kept at the ground potential. When a voltage is applied to the filament 45 from a high voltage cable (not shown) and a current flows and is heated, electrons are emitted and accelerated toward the anode 48 to form an electron beam.

  When a voltage is applied to the filament 45 in order to emit electrons, the substance remaining in the vacuum chamber 44 is ionized and collides with the diamond crystal particles of the filament 45. As a result, the surface of the diamond crystal fine particles is sputtered, the hydrogen termination on the surface is damaged, and the electron emission characteristics of the filament 45 may be deteriorated as it is. However, once desorbed hydrogen and a small amount of hydrogen (or hydrocarbon) sealed in the vacuum chamber 44 can be re-adsorbed and terminated on the surface of the diamond crystal particle using the platinum particle as a catalyst. The electron emission characteristics of the filament 45 can maintain the initial characteristics. Thereby, the open X-ray tube 40 can realize power saving, high discharge efficiency, and long life.

  Further, diamond crystals and platinum are atomized and then laminated on a metal such as tungsten as an aggregate, whereby a structure composed of diamond crystal particles and platinum particles is formed on the substrate. For this reason, even if diamond crystal particles carrying platinum fine particles existing on the surface are sputtered by positive charged ion particles, diamond crystal fine particles carrying other platinum fine particles having the same structure are exposed on the surface, so that the filament 45 The electron emission characteristics of the above are maintained. Thereby, the open X-ray tube 40 can realize power saving, high discharge efficiency, and long life.

  The anode portion 42 is obtained by incorporating an anode 48 and a pipe 50 into a lens holder 49. The electron beam passes through the hollow portion of the pipe 50, is converged to a minute diameter electron beam by the focusing coil 51 of the target portion 43, and enters the target 52.

  The target portion 43 incorporates a converging coil 51 in a cylinder under the pole piece 53 and is incorporated with an X-ray transmission window 56 sandwiched between the upper portion of the pole piece upper 54 and the target holder 55. A target 52 is mounted inside the X-ray transmission window 56 having a thickness T = about 0.5 mm. As the target 52, for example, tungsten having a thickness of about 50 μm is used, or the target 52 is directly formed on the X-ray transmission window 56.

  When an electron beam enters the target 52, X-rays are emitted there. The radiation direction has directivity, and an X-ray beam in the transmitted direction is used. The X-ray conditions of the X-ray tube are a tube voltage of 30 to 160 kV, a tube current of about 1 mA, a micro focus and a focal size of about 1 to 200 μm.

  As described above, according to the open type X-ray tube of the sixth embodiment, even if the hydrogen termination is damaged by sputtering on the surface of the diamond crystal particle carrying the platinum fine particle of the filament, it is supported on the diamond crystal fine particle. Because of the action of platinum particles, hydrogen sealed in the vacuum chamber of the open X-ray tube can be terminated, and the electron emission characteristics can be maintained, realizing power saving, high discharge efficiency, and long life. It becomes possible to do.

  Furthermore, according to the open type X-ray tube of the sixth embodiment, since the aggregate of diamond crystal particles supporting the platinum fine particles of the filament is formed in multiple layers, the surface of the filament surface is formed by the electron emission operation. Even if the surface of the diamond crystal particle carrying the platinum particle is sputtered, the diamond crystal particle carrying the platinum particle having the same structure can always emit electrons and maintain the electron emission characteristics, thus saving power. High discharge efficiency and long life can be realized.

  In the fourth to sixth embodiments, the electron source according to the first embodiment is applied. However, the electron sources according to the second and third embodiments may be applied.

  The present invention is effective for any device using an electron source.

It is drawing which shows the structure of the electron source concerning 1st Embodiment. It is drawing for demonstrating the surface structure of a diamond crystal fine particle. It is drawing explaining the reaction on the surface of the diamond crystal particle which carry | supports the platinum particle concerning this Embodiment. It is drawing explaining the charge transfer in the diamond crystal particle which carries a platinum particle. It is drawing explaining the process of carrying platinum fine particles on the surface of diamond crystal fine particles. It is the photograph which observed the diamond crystal fine particle 3 which carry | supported the platinum fine particle 4 produced by said method with TEM (transmission electron microscope). It is a graph which shows the photoelectron emission characteristic of various conventional materials. It is a graph which shows the photoelectron emission characteristic of the electron source which has the diamond crystal microparticles | fine-particles which carry | support the various conventional materials and the electron source manufacturing method concerning this Embodiment and carry | supports platinum microparticles. FIG. 9 is a graph obtained by extracting and comparing photoelectron emission amounts when the excitation light energy is 7 eV for each of various materials from the graphs showing the photoelectron emission characteristics of FIGS. 7 and 8. It is a FT-IR (Fourier transform infrared spectroscopy) spectrum of the surface of the diamond crystal fine particle which does not carry the conventional platinum fine particle. It is an FT-IR (Fourier transform infrared spectroscopy) spectrum of the surface of the diamond crystal particle carrying the platinum particle of the present embodiment. It is drawing which shows the result of having measured the relationship between the discharge start voltage of the electron source of this Embodiment, and PD product. It is drawing which shows the structure of the electron source concerning 2nd Embodiment. It is drawing explaining the charge transfer in the impurity-added diamond crystal fine particles carrying platinum fine particles. It is drawing which looked at some electron sources concerning 3rd Embodiment from the upper side. It is side surface sectional drawing which shows an example of the cold cathode discharge lamp to which the electron source demonstrated in 1st Embodiment is applied. It is side surface sectional drawing which shows an example of the magnetron to which the electron source demonstrated in 1st Embodiment is applied. It is side surface sectional drawing which shows an example of the open type | mold X-ray tube to which the electron source demonstrated in 1st Embodiment is applied.

Explanation of symbols

1, 5, 7, 13 Electron source 2 Substrate 3 Diamond crystal fine particle 4 Platinum fine particle 6 Impurity-added diamond crystal fine particle 8 Carbon nanotube 10 Cold cathode discharge lamp 11 Glass tube 12 Phosphor 14 Lead wire 20 Magnetron 21 Filament terminal 22 Capacitor 23 Coil 24a, 24b Filament support rod 25 Stem ceramic 26 Filament 27 Anode 28 Vane 29a, 29b Magnet 30 Cooling fin 31 Metal container 32 Antenna lead 40 Open X-ray tube 41 Cathode part 42 Anode part 43 Target part 44 Vacuum chamber 45 Filament 46 High voltage cable insertion port 47 Wehnelt 48 Anode 49 Lens holder 50 Pipe 51 Converging coil 52 Target 53 Below pole piece 54 Above pole piece 55 Target holder 56 X-ray transmission window

Claims (10)

A substrate,
An aggregate of diamond crystal particles formed on the substrate;
A platinum group fine particle formed on the surface of the diamond crystal particle,
An electron source characterized by The surface of the diamond crystal particle is hydrogen-terminated,
The electron source according to claim 1. The platinum group is platinum;
The electron source according to claim 1 or 2. The diamond crystal particles are fine particles,
The electron source according to any one of claims 1 to 3, wherein: The diamond crystal particles are doped with a group III or group V element,
The electron source according to claim 1, wherein: Further comprising carbon nanotubes between the diamond crystal particles,
The electron source according to claim 1, wherein: A mixing step of mixing a platinum colloid or platinic acid aqueous solution with diamond crystal particles to form a mixture;
A heat treatment step of heat-treating the mixture produced by the mixing step in a hydrogen atmosphere,
A manufacturing method of an electron source characterized by the above. The treatment temperature in the heat treatment step is in the range of 700 ° C. to 800 ° C.
The method of manufacturing an electron source according to claim 7. Comprising the electron source according to any one of claims 1 to 6,
A discharge device characterized by the above. Comprising the electron source according to any one of claims 1 to 6 and a gas containing hydrogen or hydrocarbon;
A discharge device characterized by the above.

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