Liquid deposition of salts for impact target preparation

Abstract

A target for heavy ion or electron bombardment is intended, and a method for preparing it is also intended. In this method, a) a liquid target aqueous solution of a target metal salt dissolved in water is deposited at the bottom of a metal target capsule having an opening at the top, and b) the capsule is heated to form a crystalline material. Steps a) and b) are repeated until the crystalline material contains a target amount of the target salt. The target capsule is then heated until the mass of the target capsule remains constant. To mitigate the formation of salt creep during preparation, the liquid target aqueous solution may contain about 2 to about 20 percent v / v of C2-C4 polyol, or the inner surface of the target capsule may be coated with a hydrophobic film that gives a water contact angle of about 70 to about 130° prior to liquid deposition.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Application No. 63 / 471,544, filed on 7 June 2023, the disclosure of which is incorporated herein by reference. The present invention relates to the preparation of metal salt deposits, such as radium, calcium, strontium, barium, zinc, copper, and iron, for use as targets or surrogate targets for nuclear transmutation to different metal salts after electron beam or heavy ion beam irradiation, and to the subsequent use of transmuted salt materials in medical procedures. [Background technology]

[0002] U.S. Patent No. 8,349,391 to Harfensteller et al. discloses and claims the preparation of a radium-containing target for heavy ion bombardment in the preparation of actinium. This patent teaches the production of at least one radium-containing material, which is dried from an aqueous-organic solution or suspension of such material and applied to the surface of a hollow metal cylindrical container by a surface dispersion device such that the dispersion device and the surface move relative to each other. The container comprises a base having an outer end, the base having groove-shaped recesses at the outer end of its surface. Furthermore, the aqueous-organic radium deposition solution may contain alcohols selected from the group consisting of linear and branched C1-C5 alkyl alcohols; ethanol, propanol-1, propanol-2, acetone (not alcohol), and mixtures thereof (9 columns, 14-18 rows). The C2 and C3 alcohols and acetone described have relatively low flash points, and therefore their use may result in explosive consequences that would scatter radioactive radium. For example, the flash point of ethanol is 14°C; the flash point of propanol-1 is 15°C; the flash point of propanol-2 is 12°C; and the flash point of acetone is -17°C.

[0003] In 1956, French scientist Wilfried Sebaoun published a paper [Sebaoun, Ann. Phys. (Paris), 1956, 13, 680-718] in which he described a method for preparing thin films of RaCl2 for use in determining the specific activity of radium. In that paper, Sebaoun followed the "delicate" procedure described by Hufford et al. in Transuranium Elements II, Seaborg et al., McGraw-Hill, New York, page 1149 (1949). Sebaoun disclosed that these thin RaCl2 films were prepared using a solution of tetraethylene glycol (TEG; HO(CH2CH2O)4H) and water. The inventors, using non-radioactive substitute materials for radium nitrate and radium chloride, respectively, and using radium chloride, and approximately 150 mg of material loaded into the target capsule, were unable to reproduce Sebaoun's technique using various heating and layering techniques. Our research had previously shown that it is not possible to reliably deposit BaCl2 without the use of additives due to the aggressive nature of salt creep as seen in Figure 1A. For small deposits, such as less than 150 mg, barium nitrate deposition did not require the presence of additives such as glycol, but the surface of the deposit was indented and not ideal.

[0004] Sebaoun reported that their success with RaCl2 was due to a dual heating process. First, they evaporated the solvent (water) by infrared (IR) radiation, leaving a mixture of salt and TEG. Next, they increased the heating to initiate a "partial polymerization" of TEG, which precipitated a thin film of RaCl2, followed by the removal of the organic layer. However, the claim of "partial polymerization" was not supported by any basis or evidence. TEG was reported to be an effective additive for radium deposition and was therefore used as an additive to reduce observed salt creep. The results of that study were similar to the negative results shown in Figure 1B, where heterogeneous salt formation occurred and a uniform layer was not achieved. Figure 1B illustrates the "best results" we obtained regarding salt creep arising from an aqueous BaCl2 solution using TEG as an additive. Even this result was not ideal, providing poor results that were difficult to replicate.

[0005] Sebaoun's method and process were intended for thin films. These authors reported using 0.13–0.17 mg / cm² on a target with a radius of 6 mm. [Sebaoun, p. 686.] Our results showed that TEG and Sebaoun's method are not suitable for the thick films intended herein and discussed below. More specifically, the amount of radium to be deposited in the target herein is about 100 to about 1000 times greater compared to Sebaoun's target. Due to the uncertainty of this polymerization and our inability to reproduce Sebaoun's results, we have arrived at the present invention, which is described in more detail below. [Overview of the project]

[0006] This invention generally relates to the nuclear transmutation of one isotope or element into another isotope or element by direct particle (e.g., electron or heavy ion) impact (or irradiation) of the first isotope or element, thereby forming a second isotope or element. These transmutations are illustrated using radium-226 as the first isotope, which, after impact, forms radium-225 as the second isotope. Radium-225 spontaneously decays to form actinium-225, which is useful in medical applications. One embodiment of the present invention envisions a target aqueous solution to be dried for the preparation of a metal salt target of a first isotope for transmutation of a heavy ion or electron impulse and a second isotope or a metal substitute of the first isotope. As used herein, the term “heavy ion” refers to a charged particle having a molecular weight of 1 to 238 atomic mass units (AMU). The target aqueous solution comprises water containing a dissolved target metal salt or a metal substitute of the target metal salt, present at a concentration of about 25 to about 100, preferably about 50 to about 75, in terms of mass percent of the solubility of the metal salt in water at room temperature. An improvement of the target aqueous solution is the presence of a C2-C4 polyol dissolved at about 2 to about 20 percent v / v of the solution. The C2-C4 polyol is removable during the drying of the target aqueous solution, and its presence mitigates salt creep during the drying of the target aqueous solution.

[0007] Another embodiment of the present invention relates to a method for preparing a target for heavy ion or electron bombardment. The method comprises depositing a predetermined first amount of a liquid target aqueous solution containing a dissolved target salt present at a concentration of about 25 to about 100 percent, preferably about 50 to about 75 percent, in terms of the mass of the solubility of the target salt in water at room temperature, into a metal target capsule having an upper opening. In one embodiment of this configuration, the aqueous target solution also contains dissolved C2-C4 polyols, with ethylene glycol used as the C2-C4 polyol, present at about 2 to about 20 percent, preferably about 5 to about 10 percent, of the solution in v / v. Other C2-C4 polyols are used in proportion to their molecular weight and the volume that produces their molecular weight. The C2-C4 polyols are removable during the subsequent drying of the aqueous target solution, and in a preferred embodiment, the C2-C4 polyols have a boiling point of about 300°C or less at 1 atm.

[0008] In another embodiment of this design, a liquid target aqueous solution is deposited in a target capsule, the walls of the target capsule being coated with a hydrophobic coating up to near the top level of the first volume of deposited liquid target aqueous solution, while the inner bottom of the target capsule is substantially uncoated with the hydrophobic coating. The hydrophobic coating, after application and drying, exhibits a water contact angle of about 70 to about 130° in a flat, horizontal position on the metal of the target capsule and decomposes at a temperature of about 225°C.

[0009] Regardless of which of the above embodiments is followed, the target capsule containing the deposited liquid target aqueous solution is heated at a temperature of about 40 to about 100°C, preferably at about 55 to about 75°C, for about 2 to about 6 hours to form a crystalline material. Deposition and heating are repeated until the formed crystalline material contains the desired target amount of the target salt, while densifying the layer of crystalline material (target salt). A target capsule containing a desired target amount of crystalline material is heated using a secondary heating source for about 4 hours at a temperature of about 200–300°C, or until the mass of the target capsule remains constant within a standard deviation of about 1–5% when cooled to approximately room temperature (e.g., about 20–25°C). Such a constant mass should match the theoretical target mass (i.e., the mass after the removal of crystalline water, C2-C4 polyol, and, if present, hydrophobic material to form the target). Exemplary secondary heating devices include, but are not limited to, a small oven, a muffle furnace, a high-power IR lamp, a low-power tubular heater, and a hot plate for gradually heating the target capsule at a temperature of about 240–300°C for about 4 hours.

[0010] Exemplary radioactive target salts include RaCl2, RaBr2, and Ra(NO3)2, while BaCl2, BaBr2, and Ba(NO3)2 are used as water-soluble, non-radioactive surrogate targets for radioactive salts. Further target salts and surrogates are discussed below. In a preferred embodiment of the above-described embodiment, a target capsule containing a desired amount of the target metal salt at approximately room temperature is sealed, i.e., the top opening of the target capsule is closed and sealed. In another preferred embodiment, the first heating step is continued for about 2 to about 3 hours. In another preferred embodiment, the subsequent heating step following the first heating step is continued for about 4 to about 6 hours. In a further embodiment of the above-described embodiment, the C2-C4 polyol is ethylene glycol.

[0011] A second embodiment of the present invention envisions an improved target aqueous solution for preparing a target for heavy ion or electron bombardment, the target aqueous solution comprising water containing a dissolved target salt present at a concentration of about 25 to about 100 percent by mass in terms of the solubility of the salt in water at room temperature, preferably at a concentration of about 50 to about 75 percent, the improvement being the presence of a dissolved C2-C4 polyol present at about 2 to about 20 percent, preferably about 5 to about 10 percent v / v of the solution, using ethylene glycol (EG) as the C2-C4 polyol. Other C2-C4 polyols are used in proportion to their molecular weight and the volume relative to the EG that produces their mass. The water used herein is distilled water or deionized water. Ethylene glycol is a preferred C2-C4 polyol, and it should be understood that it is preferably used as the sole C2-C4 polyol present in the target aqueous solution. However, one or more of the C2-C4 polyols can be used in combination, provided that the boiling points of each polyol used are appropriate for the capsule being used, and that the final heating temperatures of one or more are also appropriate, and that the integrity of the capsule is not compromised.

[0012] In one preferred embodiment of this embodiment, the C2-C4 polyol is ethylene glycol. In another preferred embodiment, the dissolved target salt is radium chloride, radium bromide, or radium nitrate. In a third preferred embodiment of this embodiment, the target aqueous solution contains only distilled water or deionized water, the dissolved target salt, and the dissolved C2-C4 polyol. A third preferred embodiment of the present invention is to use a hydrophobic coating on the vertical inner surface of the capsule instead of the C2-C4 polyol to suppress salt creep.

[0013] Another embodiment of the present invention is directed to a capsule for producing a target for heavy ion or electron bombardment by liquid deposition. Yet another embodiment of the present invention is a capsule for producing a target for heavy ion or electron bombardment by liquid deposition, wherein the inner wall surface, but not the bottom of the capsule, is coated with a hydrophobic coating. The coating is typically removed after the deposition is successful. Still further embodiments of the present invention are directed to capsules for liquid deposition of targets for heavy ion or electron bombardment, the capsules including one or more ridges extending from the inner bottom of the capsule. In one aspect of this embodiment, the ridges are formed in a circular shape at the bottom of the capsule.

[0014] In another aspect of this embodiment, the ridges are coated with a hydrophobic coating. In another aspect of the present invention, one or more of the above-described embodiments are utilized together to produce a target. In the drawings, which form a part of this specification,

Brief Description of the Drawings

[0015] [Figure 1]In the two panels of Figures 1A and 1B, (Figure 1A) is a photograph of a target capsule in which an aqueous solution of barium chloride was dried under an infrared lamp heater, showing unacceptable salt creep during bulk target preparation, and (Figure 1B) is a photograph showing the "best results" obtained with respect to salt creep arising from an aqueous solution of BaCl2 using 10 vol% tetraethylene glycol [HO-(CH2-CH2-O)4-H;TEG] as an additive, where the creep is shown on the upper surface of at least the interior portion of the capsule, and the heating profile was 2 hours at 65°C, then 4 hours at 250°C in a furnace (hereinafter referred to as "standard conditions"). [Figure 2] In the two panels of Figures 2A and 2B, (Figure 2A) is a photograph of a target capsule containing an aqueous solution of barium chloride at the same concentration as in Figure 1 and ethylene glycol according to the present invention, using the standard drying conditions of Figure 1, and showing slight salt creep, if present; and (Figure 2B) is a photograph showing the petrolatum-like appearance of the deposited layer after the initial heating / drying in Figure 1. [Figure 3] This is an example of an apparatus for producing a target by liquid deposition, in which the final target aqueous solution is deposited into a target capsule and the capsule is heated. [Figure 4] This illustrates a further embodiment of the apparatus of Figure 3, which has a plate in thermal contact with the underside of the target capsule. [Figure 5] This is an illustrative scheme illustrating the process for manufacturing a target according to the present invention. [Figure 6] This is an example of a target capsule to which a hydrophobic coating has been applied. [Figure 7] This is an example of a target capsule with specially fabricated external features. [Figure 8] This is an illustrative example of a cross-sectional view of the target capsule shown in Figure 6, which has a circular protrusion. [Modes for carrying out the invention]

[0016] While the present invention can be embodied in many different forms, the embodiments shown in the drawings and described in detail herein in specific embodiments are understood to be illustrative of the principles of the invention. The invention is not intended to be limited to any specific illustrated embodiments. Features of the invention disclosed herein in the specification, drawings, and claims may be important both individually and in any desired combination for the implementation of the invention in its various embodiments. Features from one embodiment may be used in other embodiments of the invention. This invention relates to the nuclear transmutation of one isotope or element into another isotope or element by direct particle (e.g., electron or heavy ion) irradiation of a first target isotope or element, thereby forming a second product isotope or element. Several candidate target metal salts were investigated as targets for such nuclear transmutation, and their possible uses were determined. These candidate target metal salts were deposited from the proposed aqueous solution of the salt into capsules or containers used to hold the target material during irradiation. However, during the drying process of the aqueous solution, the growth of salt crystals climbing the inner walls of the capsules hindered the target preparation. Such salt crystal growth is referred to herein as "salt creep."

[0017] A typical salt creep is shown in Figure 1A. Figure 1B illustrates significant salt creep using a material (tetraethylene glycol) that the prior art has suggested to be useful in overcoming salt creep, but which was not particularly useful, as can be seen in the figure of Figure 1B. Figure 2A illustrates the results of mitigating salt creep using the present invention, as described below. Salt creep causes the target material to scatter more within the target vessel, resulting in reduced irradiation effectiveness as the particle beam is restricted to a narrow cross-section for efficacy and safety reasons. In addition, salt creep reduces the density of the target material, which also leads to a lower yield of transmuted product isotopes. An important aspect of the present invention is to mitigate (reduce or suppress) salt creep so that, as a result, the prepared target remains at the bottom of the target capsule with little or no creep up the capsule wall. Each of the first isotopes or metal salts that can be used as substitutes for the first isotopes discussed in the examples has been found to respond well to the salt creep mitigation procedure discussed therein, providing a dried target similar to that shown in Figure 2A.

[0018] Target compounds to be transmuted in electron beam targets and target compounds to be transmuted used in heavy ion beam targets can be prepared in a similar manner to each other. Such targets may contain an isotope intended to be transmuted to a second isotope by irradiation with an electron beam or a heavy ion beam, or the target may contain a substitute isotope of the target isotope, which is another non-radioactive element and exhibits similar chemical properties and water solubility to at least some salts formed by both elements. Exemplary targets for electron beam irradiation include water-soluble salts of radium-226, such as RaCl2, RaBr2, or Ra(NO3)2, which can be used to produce actinium-225. Non-radioactive substitutes for these radium salts include BaCl2, BaBr2, or Ba(NO3)2. To facilitate explanation and limit redundancy, the above-mentioned substitutes for radium and barium salts are used to represent other target salts and substitutes.

[0019] Similarly, electron beam irradiation that generates photoneutrons can be used to target water-soluble salts of fluoride-19, such as potassium fluoride or sodium fluoride, for the production of fluoride-18; similar salts of bromine-79 can be used to form the salt of bromine-77; chloride or bromide of calcium-48 can be used to prepare chloride or bromide of scandium-47; water-soluble salts of copper-65 or zinc-66, such as chloride or bromide, can be used to produce copper-64; chloride or bromide of gadolinium-69 can be used to form the same salt of gadolinium-67; and potassium or sodium salts of molybdic acid prepared from molybdenum-100 can be used to form the same salt of molybdenum-99.

[0020] On the other hand, electron beam irradiation that generates photoprotons using a water-soluble salt of calcium-44 can be used to form the same salt of potassium-43; tri- or tetrachloro salts of titanium-48 can be used to produce chloride salts of scandium-47; chloride or bromide salts of nickel-58 can be used to form the corresponding salt of cobalt-57; chloride or nitrate salts of zinc-68 can be used to form the same salt of copper-67; nitrate salts of zirconium-91 can be used to form nitrate salts of yttrium-90; chloride of barium-131 ​​can be used to form chloride of cesium-131; chloride or bromide salts of erbium-167 can be used to form the corresponding chloride or bromide salts of holmium-166.

[0021] Exemplary targets for heavy ion beam irradiation include a chloride or bromide of zinc-69, which can be used to form the same salt of gadolinium-68; a chloride, bromide, or nitrate of rubidium-85 can be used to prepare the corresponding salt of strontium-82; a chloride or bromide salt of nickel-64 can be used to form the corresponding salt of copper-64; a nitrate of strontium-86 can be used to prepare the nitrate of yttrium-90; and a chloride or bromide of ytterbium-176 can be used to form the corresponding salt of lutetium-177.

[0022] The illustrative target isotopes and their substitutes are listed in the table below. In this table, target isotopes are listed using integer molecular weights, while substitute isotopes are listed using rational molecular weights, as they represent the weighted average of the molecular weights of individual elemental isotopes. [Table 1]

[0023] It should be understood that the first target isotope does not need to exist in the target capsule as an isotopically pure metal salt. Rather, the target isotope in this invention can exist in a mixture of target metal salts of parent isotopes (from which the target isotope is formed) or in a mixture of substitute metal salts. As used herein, a “substitute” isotope is a non-radioactive isotope of a first isotope, or a non-radioactive isotope of another element, whose salt has at least some of the same chemical properties and water solubility as the radioactive target isotope it substitutes for. For example, zinc-65.4 can substitute for zinc-66 or zinc-68. Similarly, calcium-40.1 can substitute for calcium-44 or calcium-48. Radium has no known non-radioactive isotopes, but barium, with a smaller molecular weight, is just below it in the alkaline earth elements of Group 2 of the periodic table and exhibits similar chemical properties to strontium, which has an even smaller molecular weight. In addition, barium and radium dichlorides form isomorphic dihydrate crystals.

[0024] It should be understood that each of the target isotopes or their substitutes, and the products produced by their irradiation as mentioned above, are well known in the art as useful precursors and desired products in one or more medical procedures. Similarly, methods for preparing target isotopes and separating the target and product isotopes after irradiation are well known to those skilled in the art and therefore do not need to be discussed herein. In exemplary embodiments, a volume of a solution containing distilled or deionized water, and a predetermined amount of a C2-C4 polyol such as ethylene glycol (EG), glycerin, propylene glycol (PG), or other C2-C4 polyols, are each mixed with a predetermined amount of a target salt sufficient to deposit a target mass of a desired salt such as RaCl2, RaBr2, or Ra(NO3)2. The composition thus prepared is homogenized to form a final target aqueous solution. A predetermined amount of this final target aqueous solution, such as about half, is dispensed into a target capsule, and an infrared (IR) lamp is placed on the target capsule to heat the deposited final target aqueous solution, initiating a process of evaporating the solvent, which is mostly water, from the deposited solution.

[0025] The intended mass of radium for deposition in the target capsule is approximately 10 mg to 1 gram. While amounts exceeding 1 gram can be used, the stated amounts have been found to be sufficient for producing and handling the intended nuclide. Preferred amounts are approximately 10 mg to 750 mg, more preferably 100 to 500 mg. The table below shows the mass of radium or barium to be deposited in the left column, and the masses of the three salts of each element to be deposited to achieve the desired amount of each element. [Table 2] [Table 3]

[0026] Figure 3 schematically illustrates an apparatus for producing a target by liquid deposition, in which the final target aqueous solution is deposited into the target capsule and the capsule 10 is heated. In an exemplary embodiment, the apparatus of Figure 3 includes a capsule (container) 10. The capsule 10 is a target capsule from which a dispensing device 12 dispenses an aqueous liquid solution 14 containing a radium salt, another salt to be irradiated, or a substitute for use in learning how to perform target preparation. The capsule 10 holds the target aqueous solution at various concentrations for various durations during the target deposition process.

[0027] The target capsule 10 can be made from one or more of the following: aluminum, steel, silicon carbide, copper, tantalum, or tungsten. In one embodiment, the target capsule is a metal, preferably an aluminum capsule 10. In a more preferred embodiment, the capsule material is aluminum Al-1050. In an alternative embodiment, the capsule is machined from aluminum Al-6061. In a further embodiment, the capsule is sealed, preferably by welding after deposition, heating, and drying of the target aqueous solution.

[0028] The dispensing device 12 contains the final target aqueous solution 14, such as the target aqueous solution described above. The dispensing device 12 distributes the target aqueous solution 14 into the target capsule 10. This can be done by dripping or by a larger volume such as flow. An automatic syringe pump or peristaltic pump is used in production. A manual syringe can be used if appropriate shielding is placed in place. The heat source 16 is located above the capsule 10. An example of a heat source is an infrared (IR) lamp that applies radiant heating to the target aqueous solution. The heat source is provided to remove the solvent, such as water and a C2-C4 polyol, from the target aqueous solution 14 within the target capsule 10. Heat can be emitted through many different pathways.

[0029] In a further embodiment, the plate 18 is provided below the bottom surface (e.g., inner bottom) 11 of the target capsule 10, in thermal contact with it. In an exemplary embodiment, the plate 18 is made of a material having high thermal conductivity. We have found that salt creep 13 can be significantly reduced by bringing the target capsule 10 into thermal contact with the plate 18 (Figure 4) (placing it on top so that heat is transferred from the bottom of the capsule), and the plate 18 itself is preferably cooled from the bottom (for example, using natural convection by air). The plate 18 can be used with the apparatus of Figure 3 described above. Furthermore, the plate 18 can be used with the final target aqueous solution described above.

[0030] While we do not wish to be bound by theory, it is conceivable that the plate surface on which the underside of the capsule rests provides active cooling to the capsule 10 by acting as a heat sink for the heat accumulated in the capsule / salt solution. The gap beneath the plate allows air to flow, convecting the plate and thereby convecting the bottom of the capsule 10. For desirable functionality, the plate is made of a material with high thermal conductivity, such as silver, copper, or aluminum, to minimize resistance to heat removal from the capsule. One preferred high thermal conductivity material for the plate is aluminum. The goal is to maximize the energy deposited directly into the salt solution (more specifically, directly into the water of the solution) while minimizing the ambient surface temperature.

[0031] We found that salt creep was noticeably worse when using other materials with lower thermal conductivity, such as steel or wood. Additionally, placing a high-thermal-conductivity plate on a low-thermal-conductivity surface worked to reduce the benefits of the high-thermal-conductivity plate. In further embodiments, the bottom surface of the target capsule 10, which is in contact with the high thermal conductivity plate 18, may or may not be actively cooled, such as by forced convection. It may also be cooled conductively or convectivally. Regarding the apparatus in Figure 3, as the target capsule heats up, the water is carefully evaporated under the action of IR radiation to help minimize the amount of voids or bubbles formed. Once most of the water is removed, what remains is a petrolatum-like deposit; that is, the solution, which was once liquid, becomes thick and gel-like, resembling petrolatum, as shown in Figure 2B. The target is then continued to heat under the lamp, and after several hours, a white deposit remains containing the deposited target salt and some form of C2-C4 polyol (see Figure 2). At this stage, the target is called "dried."

[0032] Once the first volume of the target aqueous solution becomes "dry," the second volume is added. In previous studies, when other additives were used, or when no additives were used, i.e., when no C2-C4 polyol was used, the initially deposited and dried target salt was redissolved by the addition of the second target aqueous solution, increasing the volume in the target capsule and consequently increasing salt creep. According to the present invention, when the first and second volumes were approximately equal in volume during the distribution of the second target aqueous solution, the initially deposited and dried target salt material "absorbs / adsorbs" (absorbs or adsorbs) the second target aqueous solution, and a minimal volume increase in the target capsule is observed. As described above, the same heating process was performed, and the target was thoroughly heated by an IR lamp until a very dense and uniform deposit remained. Currently, when preparing targets of approximately 100 mg or less, it is preferable to use two nearly equal amounts of target aqueous solution and two drying steps. However, it is possible to provide the addition of multiple salt solutions by using three, four, five or more additions.

[0033] Finally, in a secondary heating device such as a small oven, muffle furnace, high-power IR lamp, low-power tubular heater, and hot plate that gradually heats the target capsule to a temperature of about 200 to 300°C, preferably about 240 to 300°C, for about 4 hours, the target capsule and its contents are heated to about 200 to 300°C, preferably about 240 to 300°C, so that all the water of crystallization is evaporated and the C2-C4 polyol is removed from the target salt, or, if present, the hydrophobic coating (discussed below) is removed. Each of these multiple salt solution addition / heating processes and the use of the C2-C4 polyol is thought to contribute to the very successful execution of this technique in minimizing salt creep.

[0034] Early studies showed that it is important to heat the solution very slowly and excite and remove water molecules using only the action of an IR lamp, while leaving the C2-C4 polyol or hydrophobic coating and salt-containing petrolatum-like deposits inside the capsule. Under the current parameter and equipment settings, in the first heating stage (from liquid to petrolatum), the deposited target aqueous solution is heated in the target capsule for about 2 to 6 hours at a temperature of about 40 to about 100°C, preferably about 55 to about 75°C, to form a crystalline material. Moving away from this temperature range promotes creep of the target aqueous solution, as is observed with respect to pure salt only (Figure 1). After heating with an IR lamp is complete, it has been reported that a temperature of about 150–180°C is sufficient to remove crystal water from the deposited barium chloride and, therefore, from radium chloride [Peter et al., IJSR 8(8):1775-1779 (August 2019)]. However, the target aqueous solution present contains about 2–20 percent, preferably about 5–10 percent, of C2-C4 polyols with a boiling point above that of water at 1 atmosphere (760 mmHg) in v / v. This heating can also be carried out in a vacuum furnace, or otherwise under reduced pressure, using lower temperatures known to those skilled in the art.

[0035] More specifically, exemplary C2-C4 polyols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin, 1,2-, 1,3-, 1,4-, and 2,3-butanediols, 1,2,3-trihydroxybutane, 1,2,4-trihydroxybutane, 2-methyl-1,2-propanediol, erythritol, and threitol. At 1 atmosphere, ethylene glycol boils at approximately 200°C with a flash point of 111°C; propylene glycol boils at approximately 187°C with a flash point of approximately 99°C; 1,3-propanediol boils at approximately 214°C with a flash point of approximately 140°C; glycerin boils at approximately 290°C with a flash point of 160°C; and erythritol boils at approximately 329-331°C. 1,2-, 1,3-, 1,4-, and 2,3-butanediols have the following boiling points at 1 atm: 1,2- is 192-194°C; 1,3- is 204-207°C; 1,4- is 230°C; and 2,3- is 180-182°C, respectively. 2-Methyl-1,2-propanediol boils at 290°C. Among C4 polyols, C4 diols are preferred.

[0036] As previously discussed, aluminum is the preferred material in this invention from which capsule 10 is fabricated. Capsules can also be fabricated from other materials such as steel and various steel alloys. Work-hardened aluminum alloys, such as those preferred in this specification, tend to lose their post-annealing properties at temperatures above about 300°C. As a result, when using preferred aluminum capsules, it is most preferable to use C2-C4 polyols with a boiling point of about 300°C or less at 1 atm. A final temperature of about 240 to about 300°C was selected, using lower temperatures for lower boiling points and higher temperatures for polyols that boil at higher temperatures. It should be noted that each of the above-mentioned C2-C4 polyols has a higher flash point than Harfensteller et al.'s mono-alcohols, thereby providing a safer working environment.

[0037] An exhaust fan, typically positioned above the heating capsule 10, may also be included to assist in removing evaporated gases from adjacent areas of the heating capsule 10. If a hydrophobic coating is used instead of a C2-C4 polyol to prevent salt creep, heating to remove crystalline water and decompose and remove the hydrophobic coating may also be done as described above at a temperature of about 200 to about 300°C, preferably at a temperature of about 240 to about 300°C.

[0038] As is currently practiced, the stopping point of the heating process is determined by mass. When a certain range of mass loss is achieved, the heating process is completed, and the measured mass of the salt is compared to the theoretical mass value. During the initial heating-drying process, the target aqueous solution starts as a clear, colorless solution prior to heating. Once IR heating begins (after about 1 hour), as the solvent is removed, a salt-polyol deposit begins to form, which resembles petrolatum. Finally, as the deposit continues to be heated under the IR lamp, it begins to harden and appear to have a whiter / crystalline nature, as seen in Figure 2 (after 2-3 hours). Our study shows that the process works better if the target is dried throughout this entire time, which corresponds to the visual change in appearance observed.

[0039] When preparing radium / barium targets, RaCl2 has a water solubility of 24.5 g / 100 mL, while barium chloride is more soluble, with a solubility of approximately 35 g / 100 mL. Exemplary concentrations of barium chloride and therefore radium chloride used are approximately 50–75 percent of their solubility at room temperature in distilled or deionized water, respectively. An exemplary initial target aqueous solution utilizes 24 g / 100 mL of BaCl2, which is calculated to be approximately 68.5% of the solubility of BaCl2. A similar initial target aqueous solution of radium chloride contains approximately 12–17 g of RaCl2 / 100 mL. Current research indicates that concentrations of approximately 2 to 20 percent, preferably 5 to 10 percent, of C2-C4 polyols provide satisfactory results. A more preferred concentration (v / v) of approximately 5 to 7 percent of the preferred polyol, ethylene glycol, yields ideal results.

[0040] The inventors have shown that a hydrophobic coating on or on the inner wall of the capsule can also mitigate salt creep. Therefore, in another exemplary embodiment, the hydrophobic coating 20 is applied to the inner wall of the target capsule 10 prior to the deposition of the target liquid. When a hydrophobic coating is used, it is preferable to exclude the C2-C4 polyol from the target liquid. The hydrophobic coating is a material that does not react with the target material, the liquid of the final target aqueous solution, or the salt components, and can be removed from the wall of the capsule 10 using the heating regimen discussed above for the C2-C4 polyol-containing target composition. Figure 6A illustrates an aspect of this embodiment in which the hydrophobic coating 20 is applied to the wall of the capsule 10 and dried prior to the distribution of the target aqueous solution. After the application of the hydrophobic coating, the target aqueous solution without the C2-C4 polyol is distributed and accumulated at the bottom of the capsule 10 as the distributed solution 22. In one embodiment, the hydrophobic coating 20 is a thin film on the inner surface of the inner wall of the capsule 10. The thin film can have a thickness greater than 1 and up to about 1000 nm, preferably about 2 to about 100 nm.

[0041] An effective hydrophobic coating, after application and drying, exhibits a water contact angle of approximately 70 to 130°, preferably 80 to 120°, in a horizontal position, mitigating salt creep. For target sizes of salt material up to 150 mg (depending on the exact chemical composition), a water contact angle of at least approximately 90° is preferred. However, to increase the target mass of salt material to over 1,000 mg, a water contact angle of approximately 110° or higher is required. The mass mentioned above is approximately 0.2 to 5 cm. 3This is for a container having an internal volume of approximately 1.2 cm³, the preferred volume in this specification being about 1.2 cm³. 3 It should be noted that, although larger containers may contain a greater physical mass of salt, the method described herein allows for a significant mitigation of salt creep and thus efficient target densification. This target densification is somewhat important for irradiation as it dramatically increases production efficiency and improves space utilization.

[0042] More specifically, the surface of the inner wall 17 of the capsule 10 is partially coated with a hydrophobic coating. In this embodiment, the entire inner wall surface is not coated with the hydrophobic coating, but instead, the coating is applied up to the vicinity of the top level of the deposited target aqueous solution. The treatment of the inner wall 17 of the capsule 10 with the hydrophobic coating provides these walls with a specialized and removable surface finish. In order to allow the dried salt to adhere to the inner bottom 11 of the container (capsule) 10, the inner bottom 11 of the container 10 is substantially uncoated (about 90-100% uncoated) with the hydrophobic coating. Liquid deposition is performed as previously described after the target aqueous solution has been distributed. During liquid deposition, when the solution comes into contact with the hydrophobic coating on the wall of capsule 10, the hydrophobic coating will have a contact angle of approximately 70° to approximately 19°(θ). c This generates a solution contact angle, as illustrated in Figure 6B. The use of a hydrophobic coating enables bulk target fabrication by mitigating salt creep. The hydrophobic coating generates an ideal solution contact angle for mitigating salt creep.

[0043] During the final heating step of the final target aqueous solution deposition, the thin film coating of the hydrophobic coating decomposes and evaporates, leaving minimal residue. Plate 18 in Figure 4 can be used with target capsule 10 having the hydrophobic coating mentioned above and discussed below. The present invention is not limited to specific materials with respect to hydrophobic coatings, but two illustrative examples of hydrophobic coatings as thin film coatings are as follows. In the first example, the inventors used Aculon® AL-B (Aculon, Inc., San Diego, CA) as the hydrophobic coating. In this example, the hydrophobic coating is applied in a thickness in the range of approximately 2 to 4 nm. Decomposition for this hydrophobic coating is initiated at approximately 225°C. By heating to a maximum of approximately 250°C for 5 minutes according to standard heating conditions, the hydrophobic coating was removed from capsule 10 and the polymer layer was decomposed.

[0044] Aculon® AL-B hydrophobic coatings are designed for coating metal substrates and are disclosed and described in U.S. Patent No. 8,178,004, which is understood to be incorporated herein by reference. Generally speaking, the hydrophobic coating contains, by mass percentage (a), (b), (c), and (d) on a total mass basis, (a) 0.1 to 10 mass percent of a phosphorus-containing acid such as an organophosphoric acid, organophosphinic acid, or phosphonic acid having a perfluorocarbon group capable of forming a self-assembled monolayer on a metal substrate; (b) 0.1 to 10 mass percent of a surfactant structurally different from (a); (c) 2 to 30 mass percent of an organic solvent; and (d) 50 to 95 mass percent of water. Preferably, the structure of the above-mentioned acid having a perfluorocarbon group is [ka] (In the formula, A is an oxygen radical or chemical bond; n is 1 to 20; Y is H, F, C) n F 2n+l , C n H 2n+l (where Z is H or F; b is 0-50; m is 0-50; p is 1-20; X is a group selected from phosphoric acid, phosphinic acid, and phosphonic acid.) That is the case.

[0045] This hydrophobic coating typically exists at 1 to 5 mass percent in solvents such as a mixture of about 50 percent ethanol and about 2 percent each of methanol and isopropanol, and a mixture of about 42 percent 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane and 4-methoxy-1,1,1,2,2,3,3,4,4-nonafluorobutane. The coating composition has a viscosity of about 2 cP and provides a coating having a thickness of about 2 to about 4 nm when applied to a metal surface by rubbing or dipping. On a flat horizontal target capsule metal surface, the coating gives a water contact angle of about 116° and a water droplet sliding angle of about 20 to about 30°. Upon drying, this hydrophobic coating decomposes at about 225 °C. In a second example, the inventor used Aculon® Alt#6 as the hydrophobic coating. The Aculon® Alt#6 hydrophobic coating is disclosed and described in U.S. Patent No. 7,879,437, the disclosure of which is incorporated herein by reference.

[0046] This coating is described as a reaction product of (a) a transition metal compound selected from niobium and transition metals having electrons in f orbitals such as tantalum, titanium, zirconium, lanthanum, and tungsten, and the transition metal compound having a ligand selected from alkoxides, halides, keto acids, amines, and acylates; and (b) a silicon-containing material. The silicone-containing material is R 1 4-x SiA x or (R 1 3Si) y B or of the formula:

Chemical formula

[0047] In some preferred compositions, the silicon-containing material is given by formula: R 1 4-x SiA x It has, in the formula, R 1 is a fluorosubstituted hydrocarbon, and A is OR 2 And R 1 is structure [ka] (In the formula, A is an oxygen radical or chemical bond; n is 1 to 6; Y is F or C) n F 2n+l The reaction product is a fluorosubstituted hydrocarbon having (where b is 1 to 10, m is 0 to 6, and p is 0 to 18). For application, the coating of the reaction product is dissolved or dispersed in an organic solvent such as isopropyl alcohol, hexamethyldisiloxane, or methylene chloride for application to metal surfaces.

[0048] In this example, the hydrophobic coating is applied by immersion coating to a thickness ranging from approximately 20 to 100 nm. On a flat metal surface, the coating provides a water contact angle of approximately 90° and a water droplet sliding angle of approximately 30°. After application to a metal substrate such as aluminum and drying, the process is followed by deposition of an aqueous target or substitute target aqueous solution, drying them at low temperatures, and a final drying step in which the target-containing or substitute-containing container is heated to approximately 240 to 300°C for approximately 4 hours to decompose this fluoride / silicone-based layer. As illustrated in Figure 7, the capsule 10 may have specially fabricated external features such as a raised portion 30. The special external features or raised portion 30 are provided inside the capsule 10 to mitigate salt creep through their external shape.

[0049] In this embodiment, in a manner similar to that discussed above, the target aqueous solution is distributed from the distributor 12 and accumulated as a solution 22 distributed at the bottom of the capsule 10. In this embodiment, the target aqueous solution is distributed around a raised portion 30 at the bottom of the capsule 10. The raised portion provides physical separation of the target aqueous solution, which reduces solvent movement during evaporation. In addition, the raised portion significantly increases the surface area of ​​capsule 10 relative to the volume ratio of the target aqueous solution in the region of interest, reducing salt creep and improving heat removal from the salt during subsequent irradiation. As a result, the distributed target aqueous solution is subdivided into smaller components by the machined external features. Some of the many benefits of this configuration directly derive from the increased surface area in contact with the salt, the increased maximum salt capacity, and the increased heat removal from the salt.

[0050] In one exemplary embodiment of this design, as shown in the cross-sectional view of Figure 8, the protrusion 30 is formed as a series of circular protrusions 32 on the bottom of the capsule 10. The present invention considers other possible protrusions and shapes for the special external feature 30 on the bottom of the capsule 10. In this design, the inventors consider that such a circular shape is the easiest to manufacture, and therefore a circular shape is shown as the protrusion. However, other shapes (e.g., a rectangle) can be used if the external shape of the target capsule 10 is changed according to a rectangle. The present invention also envisions various configurations and is not limited to special external features or the number of raised parts 32. The desired distance between the raised parts can be determined by manufacturability. This distance and manufacturability may also be influenced by the height of the raised parts. The purpose of the special external features or configuration of the raised parts is to maximize the surface area in contact with the salt, according to manufacturability. Furthermore, the number of raised sections can be determined by the thickness of the raised sections. The thinner the raised sections, the more possible raised sections can be included. The minimum distance between the raised sections needs to be sufficient to allow the final target aqueous solution to flow into the valleys between the raised sections and form the distributed final target aqueous solution 22 between the raised sections on the bottom of the capsule 10.

[0051] It is also desirable that the target aqueous solution does not remain on any particular external features or protrusions due to surface tension. In light of this, it is desirable that the thickness of the protrusions or circles be as thin as possible within the manufacturing limits. Therefore, the upper part of the protrusion may be tapered, with the tip being curved or blade-like, as shown as flat in Figure 8. Further possible limitations regarding the number and thinness of the protrusions may be influenced by the removal of water and the C2-C4 polyol or hydrophobic coating during the final heat removal process. In one embodiment, a specially fabricated external feature or protrusion is formed from the same material as the target capsule 10. In a further embodiment, the protrusion is a machined feature that rises from the capsule 10. The protrusion is not limited to being made from the same material as the capsule 10.

[0052] In a further embodiment, the height 32 of the raised portion 30 is above the waterline. The aforementioned surface treatment for salt adhesion, which involves machining the base of the capsule 10 to improve salt adhesion, provides a surface roughening finish below the waterline (only 0.1 mm). Raising the height of the raised portion above the waterline increases salt adhesion and heat removal from the salt. In a further embodiment, the hydrophobic coating described above can be applied to the surface of specially fabricated external features or protrusions. For example, the hydrophobic coating can be applied to or dipped into the protrusions. This can further reduce salt creep.

[0053] In a further embodiment, the above-described final target aqueous solution is dispensed into a target capsule 10 having specially fabricated external features or protrusions. In a further embodiment, the target capsule 10 and the protrusions are coated with a hydrophobic coating. The plate 18 in Figure 4 can be used in conjunction with a target capsule 10, which is a specially fabricated external feature or raised portion. Examples

[0054] (Example 1) In the illustrative example schematically shown in Figure 5, a total of 0.641 mL of the final target aqueous solution containing 7% ethylene glycol is added in two approximately equal volumes to produce a target containing 154 mg of BaCl2. When the salt concentration is reduced to a 50 percent solubility concentration, a volume of 0.905 mL of the final target aqueous solution is required, preferably distributed in two volumes of approximately 0.453 mL each. Approximately half of the first volume was heated under an IR lamp at approximately 55-75°C for approximately 2-3 hours, and then allowed to cool (low-temperature drying process). The remaining target aqueous solution was added to the target capsule, and the IR heating process was repeated for approximately 4-6 hours. The target capsule was placed on a secondary heating device and heated at a temperature of approximately 240-300°C for 4 hours to produce dried salt, with salt creep mitigated as shown in Figure 2A.

[0055] (Example 2) As examples of other elements treated similarly to barium salts, substitute metal salt target studies were conducted using Sr(NO3)2, CaCl2, Fe(NO3)3, ZnCl2, and Cu(NO3)2, similar to those in Example 1, shown in Figures 2A and 2B, and schematically shown in Figure 5. Using each of these specific salts, studies were performed using the standard parameters previously used for the low-target barium / radium liquid deposition. Some studies used ethylene glycol as a creep relaxant, while others used a hydrophobic coating as a relaxant. Each substitute target salt was also dried without a creep relaxant, i.e., as a simple aqueous solution to serve as a control. Therefore, when ethylene glycol was used as a creep mitigating agent, a substitute metal salt was added at a concentration of 12 g / 50 mL, and the mixture was stirred until the metal salt dissolved and a substitute target aqueous solution was formed, to prepare an aqueous solution containing ethylene glycol at a concentration of 7% (v / v).

[0056] For use in studies utilizing hydrophobic coatings and controls without hydrophobic coatings, water alone and a metal substitute solution containing 12 g / 50 mL of the metal substitute salt were used as controls to compare salt creep with an ethylene glycol-containing solution. Two aliquots of approximately equal volumes of a research-grade surrogate target salt solution and its control solution were added to the capsule 10 at a time, one aliquot at a time, and then dried. A second aliquot of the same research or control solution was then added, and then dried. After each aliquot is delivered to the target capsule, infrared (IR) heating at 65°C for approximately 2 hours is used in each of the drying processes described above. Next, each of the dried capsules was heated to a certain mass by furnace heating at 250°C for 4 hours. Therefore, each individual material had deposition performed either without applying relaxation (i.e., salt + water), with a candidate relaxation agent which is a C2-C4 polyol, or with a hydrophobic coating applied as described above. It is important to note that no parameter optimization was performed for each individual salt form, and the optimization parameters for barium / radium deposition were used.

[0057] The use of the mitigating agents described herein for each of the alternative substitute metal salt forms mentioned provided a significant reduction in salt creep compared to the absence of the mitigating agent. A clear example of this is given in the table below, where nearly identical amounts of ZnCl2 deposition were examined, one with mitigating applied and the other without. The mitigating agent in this case was the hydrophobic coating, Aculon® AL-B. [Table 4]

[0058] Relaxation studies using Sr(NO3)2, CaCl2, Cu(NO3)2, and Fe(NO3)3 yielded similar results to those described above. Therefore, while using water alone as a solvent resulted in salt creep during drying, the use of a relaxant mitigated the creep. The presence of ethylene glycol in copper nitrate made the solution bluer, and therefore a hydrophobic coating was used for copper nitrate studies.

[0059] Specific embodiments have been described for the purpose of illustrating how the present invention can be carried out and used. It should be understood that implementations of the present invention and other variations and modifications of various aspects thereof will be obvious to those skilled in the art, and that the present invention is not limited by the specific embodiments described. Features described in one embodiment can be implemented in other embodiments. It should be understood that the subject matter disclosure encompasses all variations, modifications, or equivalents that fall within the spirit and scope of the present invention and the fundamental principles disclosed and claimed herein.

[0060] Each of the patents, patent applications, and documents cited herein is incorporated by reference. The use of the articles "a" or "an" is intended to include one or more. The foregoing description and examples are intended to be illustrative and should not be construed as limiting. Further modifications within the spirit and scope of the present invention are possible and will be readily apparent to those skilled in the art.

Claims

1. A target aqueous solution, dried for preparing a metal salt target of a first isotope for heavy ion or electron bombardment and nuclear transmutation to a second isotope or a metal substitute of the first isotope, comprising water containing a dissolved target metal salt or a metal substitute thereof, present at a concentration of about 25 to about 100 in mass percentage of the solubility of metal salts in water at room temperature, wherein the improvement point is C dissolved at about 2 to about 20 percent v / v of the solution. 2 -C 4 The presence of a polyol, and the aforementioned C 2 -C 4 A target aqueous solution in which the polyol can be removed during drying of the target aqueous solution, and salt creep during drying of the target aqueous solution is mitigated.

2. Said C 2 -C 4 The target aqueous solution according to claim 1, wherein the polyol has a boiling point of approximately 300°C or less at 1 atmosphere.

3. The target aqueous solution according to claim 1, wherein the first isotope of the dissolved target salt is selected from the group consisting of radium-226, fluorine-19, bromine-79, calcium-48, copper-65, zinc-66, gadolinium-69, molybdenum-100, calcium-44, titanium-48, nickel-58, zinc-68, zirconium-91, barium-131, erbium-167, zinc-69, rubidium-85, nickel-64, strontium-86, ytterbium-176, barium-137.3, copper-63.5, zinc-65.4, strontium-87.6, iron-55.8, and calcium-40.

1.

4. A method for preparing a target for heavy ion or electron irradiation, a) A step of depositing a predetermined first amount of a liquid target aqueous solution containing a dissolved target metal salt containing the first isotope for nuclear transmutation into a second isotope or a metal substitute salt of the first isotope by irradiation into a metal target capsule having an upper opening, wherein the target metal salt is present at a concentration of about 25 to about 100 in mass percentage of the solubility of the target salt in water at room temperature, i) dissolved C present at about 2 to about 20 percent v / v of the solution 2 -C 4 a polyol having a boiling point of about 300 °C or less at 1 atm, C 2 -C 4 a polyol, or ii) A step of depositing a liquid target aqueous solution into a target capsule, wherein the wall of the target capsule is coated with a hydrophobic coating up to near the uppermost level of a first volume of the deposited liquid target aqueous solution, the hydrophobic coating, after application and drying, exhibits a water contact angle of about 70 to about 130° at a flat horizontal position on the metal of the target capsule, decomposes at a temperature of about 225°C, and the inner bottom of the target capsule is substantially not coated with the hydrophobic coating. b) A step of heating the target capsule at a temperature of approximately 40 to approximately 100°C for approximately 2 to approximately 6 hours to form a crystalline material, c) Repeating steps a) and b) until the formed crystalline material contains the desired target amount of the target salt, d) A step of treating the crystalline material-containing target capsule with a secondary heat source, heating the target capsule at a temperature of approximately 200 to approximately 300°C for approximately 4 hours, or until the mass of the target capsule remains constant when cooled to approximately room temperature. A method that includes this.

5. The method according to claim 4, further comprising step e) sealing the target capsule.

6. The method according to claim 4, wherein the first heating step in step b) is continued for about 2 to about 3 hours.

7. The method according to claim 6, wherein the heating step c) that follows is continued for about 4 to about 6 hours.

8. Said C 2 -C 4 The method according to claim 4, wherein the polyol is ethylene glycol.

9. The method according to claim 4, further comprising cooling the target capsule with a plate that is in thermal contact with the lower side of the target capsule.

10. The method according to claim 9, wherein the plate is made from a high thermal conductivity material.

11. The method according to claim 4, wherein the first isotope of the dissolved target metal salt is selected from the group consisting of radium-226, fluorine-19, bromine-79, calcium-48, copper-65, zinc-66, gadolinium-69, molybdenum-100, calcium-44, titanium-48, nickel-58, zinc-68, zirconium-91, barium-131, erbium-167, zinc-69, rubidium-85, nickel-64, strontium-86, ytterbium-176, barium-137.3, copper-63.5, zinc-65.4, strontium-87.6, iron-55.8, and calcium-40.

1.

12. Prior to drying, the hydrophobic coating has a mass percentage of (a), (b), (c), and (d) based on the total mass, (a) 0.1 to 10 mass percent of a phosphorus-containing acid such as an organic phosphoric acid, organic phosphinic acid, or phosphonic acid having a perfluorocarbon group capable of forming a self-assembled monolayer on the metal substrate, (b) A surfactant in a structurally different form from (a) in a mass of 0.1 to 10 percent, (c) 2 to 30 mass percent of an organic solvent, (d) 50-95 mass percent of water and The method according to claim 4, comprising:

13. The acid having the perfluoro hydrocarbon group has a structure 【Chemistry 1】 The method according to claim 12, having the following characteristics. (In the formula, A is an oxygen radical or a chemical bond, n is between 1 and 20. Y is H, F, C n F 2n+l , C n H 2n+l And, Z is either H or F, b is between 0 and 50. m is between 0 and 50. p is between 1 and 20. X is a group selected from phosphoric acid, phosphinic acid, and phosphonic acid.

14. The hydrophobic coating (a) A transition metal compound wherein the transition metal is selected from niobium and other transition metals having electrons in their f orbitals, such as tantalum, titanium, zirconium, lanthanum, and tungsten, and the transition metal compound has a ligand selected from alkoxides, halides, keto acids, amines, and acylates, and (b) Silicon-containing materials The method according to claim 4, comprising the reaction product of the

15. The silicon-containing material is R 1 4-x SiA x or (R 1 3 Si) y B or formula: 【Chemistry 2】 The method according to claim 14, having a formula selected from organic (poly)siloxanes and organic (poly)silazanes having units. (In the formula, R 1 These are hydrocarbons or substituted hydrocarbon radicals containing 1 to 100 carbon atoms, which are identical or different in their respective existences. A is hydrogen, halogen, OH, OR 2 , or O-C(O)-R 2 And, B is NR 3 3-Y And, R 2 This is a hydrocarbon or substituted hydrocarbon radical containing 1 to 12 carbon atoms. R 3 is hydrogen or R 1 (This is the same as x being 1, 2, or 3; y being 1 or 2)

16. A metal capsule for producing a target for heavy ion or electron impact by liquid deposition, wherein the inner surface of the capsule is coated with a hydrophobic coating, the coating, after application and drying, exhibits a water contact angle of about 70 to about 130° in a flat horizontal position on the metal of the target capsule, decomposes at a temperature of about 225°C, and the inner bottom of the target capsule is substantially uncoated with the hydrophobic coating.

17. A capsule for liquid deposition of a target for heavy ion or electron impact, comprising one or more protrusions extending from the internal bottom of the capsule.

18. The capsule according to claim 17, wherein the raised portion is formed in a circular shape at the bottom of the capsule.

19. The capsule according to claim 17, wherein the raised portion is coated with a hydrophobic coating, the coating, after application and drying, exhibits a water contact angle of about 70 to about 130° in a flat horizontal position on the metal of the target capsule, decomposes at a temperature of about 225°C, and the inner bottom of the target capsule is substantially not coated with the hydrophobic coating.

Images