Method for recovering 186w target material in 188re preparation process

Abstract

A method for recovering a 186W target material during a 188Re preparation process, which method comprises the following steps: obtaining a 186W-containing waste liquid, removing metal impurities from the waste liquid, and filtering same to obtain a filtrate; precipitating and filtering the filtrate to obtain a 186W-containing precipitate; and drying the 186W-containing precipitate, and roasting same at a high temperature to obtain a 186W powder. In the method, 186W in a solid is effectively converted into a solution, and by means of a chemical precipitation method, impurity metals are removed, and 186W in a tungsten-rhenium generator is recovered, thereby greatly reducing pollution of solid and liquid waste to the environment and reducing the waste treatment cost of a 188Re production process.

Description

A sort of 188 During the preparation of Re 186 W target material recovery method Technical Field

[0001] The present invention relates to the technical field of target material recovery in the production process of radioactive isotopes, and specifically relates to a 188 During the preparation of Re 186 W target material recovery method. Background Art

[0002] 188 The physical half-life of Re is 17h, and the decay process emits high-energy β rays (E β-max =2.118MeV(70.7%), E β- =1.962MeV (26.3%), with a maximum tissue range of 11mm. 95% of the beta rays are absorbed within 4mm. While delivering radiation doses to kill cancer cells, it causes minimal damage to surrounding normal tissues, making it suitable for internal irradiation therapy. It also emits 0.155MeV (15.61%) gamma rays, which can be used to study the biological distribution of radionuclides, radiation doses, and pharmacokinetics. 188 Re has excellent nuclear physical and chemical properties and can be used for cancer diagnosis and treatment effect evaluation. It is an ideal integrated diagnosis and treatment radionuclide. 188 Re-labeled radiopharmaceuticals are used in the treatment of bone tumors, head and neck soft tissue tumors, radiosynovectomy of rheumatoid arthritis, and radioimmunotherapy of tumors, and have achieved significant therapeutic effects. 188 Re's research on radionuclide interventional internal irradiation of malignant tumors has also made great progress. 188 The demand for Re is also increasing.

[0003] preparation 188 The methods of Re mainly include: (1) nuclear reactor irradiation high purity 187 Re target, 187 Re(n,γ) 188 Re reaction produces supported 188 Re; (2) using nuclear reactor irradiation 186 W target, 186 W(n,γ) 187 W(n,γ) 188 W reaction to obtain a longer half-life 188 W(T 1 / 2 = 69.4 days), and the parent nuclide decays to generate the target product 188 Re, and then use chemical means to extract the decay equilibrium system ( 188 W- 188Re) Isolate the carrier-free 188 Re. Among them, neutron irradiation is used to produce 188 Re requires high abundance 187 Re target material, obtained 188 Re has a carrier and cannot meet the requirements of areas far away from the reactor. 188 However, the tungsten rhenium generator is convenient for transportation and its preparation 188 Re has no carrier and can provide a long-term source for applications in the field of nuclear medicine. Therefore, the research on tungsten-rhenium generators has become a hot topic in the field of isotope preparation and application.

[0004] Currently, tungsten-rhenium generators primarily include alumina chromatography column tungsten-rhenium generators, irradiation-type tungsten-rhenium generators, and gel-type tungsten-rhenium generators. Alumina chromatography-type tungsten-rhenium generators have reached commercialization conditions, while chromatography-type tungsten-rhenium generators containing zirconium or titanium polymers as adsorbents are still in the research stage. For example, the Japan Atomic Energy Research Institute has conducted research on tungsten-rhenium generators using PZC (polyzirconium compound) as an adsorbent. The Bhabha Atomic Research Center in India subsequently synthesized a new high-capacity adsorption material, nanozirconia, with a static adsorption capacity of 330 mg / g for W. Numerous scholars have also conducted research on irradiation- and gel-type tungsten-rhenium generators. For example, the Australian Nuclear Science and Technology Organization has developed a tungsten-rhenium generator based on titanium tungstate gel using non-enriched tungsten, with a tungsten content and yield of 38% and 67% respectively. The China Nuclear Power Research and Design Institute has developed a tungsten-rhenium generator based on zirconium tungstate gel, titanium tungstate or ZrSiW gel using enriched tungsten, with a tungsten content and yield of 40-45% and 70-74%.

[0005] When the elution time of the chromatographic, irradiation and gel type tungsten-rhenium generator is long enough or 188 When W has almost completely decayed, the column still contains a large amount of 186 W, also contains 30-35% in the gel synthesis supernatant 186 W. Enrichment 99% and above 186 The market price of W is 3500-4500 yuan / gram. Therefore, the supernatant and the column 186 W recycling to reduce 188 Re production cost. 186 The recycling of W target material is the key to realize large-scale production without carrier 188 The key to Re. 186 The recycling of W target materials is a technical gap.

[0006] In view of this, this patent application is filed.

[0007] Summary of the Invention

[0008] The present invention provides a 188 During the preparation of Re186 The recovery method of W target material fills the existing 188 During the preparation of Re 186 There is a technical gap in W target material recycling.

[0009] The purpose of the present invention is to provide a 188 During the preparation of Re 186 The method for recovering W target material comprises the following steps:

[0010] (1) Get the content 186 W waste liquid, removing metal impurities in the waste liquid, filtering to obtain a filtrate;

[0011] (2) The filtrate was precipitated and filtered again to obtain 186 precipitation of W;

[0012] (3) Dry, grind and calcine the precipitate to obtain 186 W powder.

[0013] The present invention includes the following embodiments: 186 W is converted into solution and the impurity metals are removed by chemical precipitation to obtain a high chemical purity 186 W, and then the tungsten-rhenium generator is treated by chemical precipitation. 186 The results show that this method can greatly reduce the pollution of solid and liquid waste to the environment and reduce 188 The recycling process of the present invention is simple and practical to operate, has low economic cost, and is carrier-free. 188 High value for Re production 186 The recycling of W target material provides an effective solution.

[0014] In an optional embodiment, in step (1), an inorganic salt is used to remove metal impurities in the waste liquid;

[0015] The inorganic salt includes any one or more of sodium hydroxide, sodium chloride, sodium carbonate, and sodium sulfate;

[0016] The concentration of the inorganic salt is 1 mol / L to 10 mol / L, and the pH value is 8-14.

[0017] In an optional embodiment, the metal impurities are cations of any one or more of Al, Ti, Zr, Ca, and Ba.

[0018] In an optional embodiment, in step (2), the pH of the filtrate is adjusted to less than or equal to 2 for precipitation, allowed to stand, and filtered to obtain a precipitate containing 186W; the pH of the filtrate is adjusted with an acid solution, wherein the acid solution includes hydrochloric acid, sulfuric acid, nitric acid, etc., and the acid concentration is 0.1 to 10 mol / L;

[0019] The temperature during the precipitation operation is 10°C to 60°C.

[0020] In an optional embodiment, in step (3), the precipitate is placed at a constant temperature of 60° C. to 120° C. for drying, and is ground into powder after drying.

[0021] In an optional embodiment, in step (3), the high temperature calcination temperature is 200° C. to 500° C., and the calcination time is 2 h to 4 h.

[0022] In an optional embodiment, 186 The waste liquid of W is the filler dissolution liquid of the gel type or irradiation type tungsten-rhenium generator, or the column desorption liquid of the chromatography type tungsten-rhenium generator, or the supernatant generated during the synthesis process of the column filling material of the gel type tungsten-rhenium generator.

[0023] In the embodiment of the present invention, the solid in the gel type, irradiation type tungsten rhenium generator, chromatography type tungsten rhenium generator, gel type tungsten rhenium generator 186 W is converted into solution, providing a basis for the removal of metal impurities and a carrier-free 188 It provides an important foundation for the large-scale production of Re.

[0024] In an optional embodiment, the column filler of the gel-type, irradiated tungsten-rhenium generator includes one of titanium tungstate, zirconium tungstate, ZrSiW gel, tungsten-containing binary gel material, and tungsten-containing binary gel material;

[0025] dissolving the column filler with a dissolving reagent to obtain a dissolving solution;

[0026] The dissolving agent includes any one or more of sodium hydroxide, hydrochloric acid, sulfuric acid, and nitric acid.

[0027] The concentration of sodium hydroxide should be 1-10 mol / L; the concentration of hydrochloric acid, sulfuric acid, nitric acid, or a mixed acid should be 1-12 mol / L. Dissolution methods include heating and stirring or microwave digestion. Heating methods include induction cookers, hot plates, oil baths, and microwave digestion apparatus. The heating time should be 10-180 minutes, the heating temperature should be 60-200°C, and the stirring rate should be 100-300 rpm.

[0028] In an optional embodiment, the column packing of the chromatography type tungsten rhenium generator includes any one of acidic alumina, Dowex 1X8 cationic resin, organophosphorus resin; and other organic / inorganic adsorbents;

[0029] A desorbent is pumped into the upper end of the column of the chromatographic tungsten-rhenium generator to obtain a desorbent liquid;

[0030] The desorbent includes any one or more of sodium hydroxide, sodium carbonate, sodium sulfate, sodium chloride, nitric acid, and hydrochloric acid;

[0031] The concentration of the desorbent is 0.1-8 mol / L, the desorption temperature is 15-30°C, and the flow rate of the desorbent onto the column is 1-3 mL / min.

[0032] In an optional embodiment, the supernatant produced during the synthesis of the column filling material of the gel-type tungsten-rhenium generator is the supernatant produced during the synthesis of any one of titanium tungstate, zirconium tungstate, ZrSiW gel, tungsten-containing binary gel material, and tungsten-containing ternary gel material.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] An embodiment of the present invention provides a 188 During the preparation of Re 186 The recovery method of W target material effectively recovers 186 W is converted into solution and the impurity metals are removed by chemical precipitation to obtain a high chemical purity 186 W, and then the tungsten-rhenium generator is treated by chemical precipitation. 186 W recycling greatly reduces the pollution of solid and liquid waste to the environment and reduces 188 The recycling process of the present invention is simple and practical to operate, has low economic cost, and is carrier-free. 188 High value for Re production 186 The recovery of W target material provides an effective solution. It fills the gap of recovery from gel type, chromatography and irradiation type tungsten rhenium generator. 186 Technical gap in W target materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0036] FIG. 1 is a diagram of a method provided in an embodiment of the present invention. 188 During the preparation of Re 186 Flowchart of the W target material recovery method.

[0037] FIG2 is an XRD test diagram of the WO3 powder obtained in Example 1 and Example 4 of the present invention. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0040] It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. In the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0041] In the description of the embodiments of the present application, the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] In the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed," "having," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific contexts.

[0043] Example 1:

[0044] For the zirconium tungstate gel type tungsten rhenium generator 186 W recovery methods include:

[0045] 1) Take out the column packing from the gel-type tungsten-rhenium generator and weigh 1000 mg of tungsten [ 186Place zirconium chloride gel in a 250 mL beaker and add 30 mL of hydrochloric acid solution with a concentration of 1-12 mol / L. Heat (boil) on an induction cooker to dissolve. After 10-15 minutes, the gel particles are completely dissolved to obtain a clear and transparent solution.

[0046] 2) Cool to room temperature, add excess 5 mol / L sodium hydroxide solution to the solution to form a white precipitate, and let it stand at room temperature for 24 hours;

[0047] 3) Use high-speed centrifugation to separate the white precipitate and remove the supernatant, then add 5 mol / L hydrochloric acid solution to the supernatant to adjust the pH value to less than 1 to generate a yellow precipitate, let it stand for 24 hours, and filter it. 186 The precipitation of W.

[0048] The W content in the filtrate in step 3) was analyzed by ICP-AES, and the recovery rate of the WO3 target material was found to be 99.2%.

[0049] 4) Install 186 The culture dish with W precipitation was transferred to a vacuum freeze dryer and dried for more than 24 hours at a temperature of 20°C and a vacuum degree of ≦10Pa. The dried solid was a powder and did not need to be ground.

[0050] 5) The powder was placed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain WO3 powder.

[0051] The X-ray diffraction spectrum of the powder was analyzed by X-ray diffractometer, as shown in Figure 2. As can be seen from the XRD spectrum, the peak positions of the product, raw material and PDF card are completely consistent, proving that the product is WO3.

[0052] Example 2:

[0053] For titanium tungstate irradiated tungsten-rhenium generator 186 W recovery methods include:

[0054] 1) Take out the column packing from the irradiated tungsten-rhenium generator and weigh 1000 mg of tungsten [ 186

[0066] Titanium dioxide gel was placed in a 250 mL beaker, 30 mL of concentrated hydrochloric acid was added, the concentration of the hydrochloric acid solution was 1-12 mol / L, and the solution was heated (boiling) on ​​an induction cooker to dissolve. After 5-10 minutes, the gel particles were completely dissolved to obtain a clear and transparent solution.

[0055] 2) Cool to room temperature, add excess 2% sulfuric acid solution to the solution to form a titanium-containing precipitate, and let it stand at room temperature for 24 hours;

[0056] 3) Use high-speed centrifugation to separate the titanium-containing precipitate and remove the supernatant, then add 5 mol / L hydrochloric acid solution to the supernatant to adjust the pH value to less than 1 to generate a yellow precipitate, let it stand for 24 hours, and filter it.186 Precipitation of W

[0057] The W content in the filtrate was analyzed by ICP-AES, and the recovery rate of WO3 target material was found to be 99%.

[0058] 4) The petri dish containing the precipitate was transferred to a constant temperature dryer and dried at 80° C. for more than 12 h. The dried solid was ground into powder.

[0059] 5) The powder was placed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain WO3 powder.

[0060] Example 3:

[0061] For ZrSiW gel type tungsten rhenium generator 186 W recovery methods include:

[0062] 1) Weigh 1000mgZrSi 186 The W gel was placed in a 250 mL beaker, 30 mL of 5 mol / L sodium hydroxide solution was added, and the mixture was heated (boiled) on an induction cooker to dissolve. The gel particles were completely dissolved after boiling for 3-5 minutes to obtain a clear and transparent solution.

[0063] 2) Cool to room temperature. A white precipitate will gradually precipitate during the cooling process. Let it stand at room temperature for more than 24 hours.

[0064] 3) Use high-speed centrifugation to separate the white precipitate and remove the supernatant, then add 5 mol / L hydrochloric acid solution to the supernatant to adjust the pH value to less than 1 to generate a yellow precipitate, let it stand for 24 hours, and filter it. 186 W precipitation.

[0065] The W content in the filtrate was analyzed by ICP-AES, and the recovery rate of WO3 target material was 99.2%.

[0066] 4) The petri dish containing the precipitate was transferred to a constant temperature dryer and dried at 80° C. for more than 12 h. The dried solid was ground into powder.

[0067] 5) The powder was placed in a crucible and calcined in a muffle furnace at 400°C for 3 h to obtain WO3 powder.

[0068] Example 4:

[0069] For chromatographic tungsten-rhenium generators 186 W recovery methods include:

[0070] 1) 2 g of acidic Al2O3 was loaded into an SPE column with a polytetrafluoroethylene frit. 20 mL of a 0.5 mol / L natural WO3 solution with a pH of 2-3 was pumped into the column at a flow rate of 2 mL / min using a peristaltic pump. The concentration of the effluent was measured, and the column adsorption capacity was found to be 116 mg / g.

[0071] 2) Rinse the adsorption column with 20 mL of 0.9% NaCl solution;

[0072] 3) Using a peristaltic pump, 20 mL of 0.5 mol / L desorbent was pumped from top to bottom into the adsorption column at a flow rate of 2 mL / min to desorb the aluminum oxide to obtain a desorbed solution with a desorption efficiency of 97%;

[0073] 4) Add an excess amount (20 mL) of 5 mol / L sodium hydroxide solution to the desorption solution to form a white precipitate, and let it stand at room temperature for 24 hours;

[0074] 5) Remove the white precipitate by filtration, then add 5 mol / L hydrochloric acid solution to the filtrate to adjust the pH to less than 1 to form a yellow precipitate. Let it stand for 24 hours, filter it, take the filter cake and dry it at 80°C for 12 hours, then take it out and grind it into powder.

[0075] The W content in the filtrate was analyzed by ICP-AES, and the recovery rate of WO3 target material was 99%;

[0076] 6) The powder was placed in a crucible and calcined in a muffle furnace at 400°C for 3 hours to obtain WO3 powder. The X-ray diffraction spectrum of the powder was analyzed by X-ray diffractometer, as shown in Figure 2.

[0077] It can be seen from the XRD spectrum that the peak positions of the product, raw material and PDF card are completely consistent, proving that the product is WO3.

[0078] Example 5:

[0079] The supernatant produced during the preparation of tungsten-rhenium generator fillers 186 W recovery methods include:

[0080] 1) Weigh 2g of enriched tungsten oxide into a 250mL beaker, add 20mL of 5mol / L sodium hydroxide solution, and heat and stir at 80°C to dissolve until the liquid becomes clear and transparent. Cool to room temperature, and adjust the pH of the sodium tungstate solution to 4-5 with 5mol / L hydrochloric acid solution. Set aside.

[0081] 2) Under magnetic stirring, slowly drop the sodium tungstate solution into the ZrOCl2·8H2O solution. After a period of reaction, adjust the pH of the solution to about 3, then stir and react at 80°C for 90 minutes. Let it stand until the gel settles and separates, and filter to obtain the gel cake and supernatant (filtrate).

[0082] 3) Add an excess of 5 mol / L sodium hydroxide solution to the supernatant to form a white precipitate, and let it stand at room temperature for 24 hours;

[0083] 5) Remove the white precipitate by filtration, then add 5 mol / L hydrochloric acid solution to the filtrate to adjust the pH value to less than 1 to generate a yellow precipitate. Let it stand for 24 hours and filter to obtain a gel filter cake.

[0084] The W content in the filtrate was analyzed by ICP-AES, and the recovery rate of WO3 target material was 99.2%.

[0085] 6) Transfer the culture dish containing the gel cake to a vacuum freeze dryer and dry it for more than 12 hours at a temperature ≤ -50°C and a vacuum degree ≤ 10 Pa. The freeze-dried solid is a powder and does not need to be ground.

[0086] 7) The powder was placed in a crucible and calcined in a muffle furnace at 300°C for 2 h to obtain WO3 powder.

[0087] The present invention utilizes chemical dissolution, desorption and precipitation processes, which are simple to operate. 186 W recovery rate is high (≥99%), and effectively reduces the solid waste generated by the generator. 186 W exists in the form of oxide, which is convenient for reuse and greatly reduces the 188 Re preparation cost, for large-scale production without carrier 188 Re laid the foundation and promoted the development of medical isotope and pharmaceutical industry.

[0088] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A 188 method for recycling W target material during the preparation of Re 186 is provided. It is characterized in that it includes the following steps: (1) Obtain the waste liquid containing 186 W, remove the metal impurities in the waste liquid, filter, and obtain the filtrate; (2) Precipitate the filtrate and filter it again to obtain a precipitate containing 186 W; (3) Dry and calcine the precipitate containing 186 W to obtain 186 W powder.

2. According to claim 1, a 188 During the Re preparation process 186 Method for recycling W target materials It is characterized in that in step (1), inorganic salts are used to remove metal impurities in the waste liquid; the inorganic salts include any one or several of sodium hydroxide, sodium chloride, sodium carbonate, and sodium sulfate; the concentration of the inorganic salts is 1 mol / L to 10 mol / L, and the pH value is 8 - 14.

3. A method for recycling W target material according to claim 1 188 During the preparation process of Re 186 ​ It is characterized in that the metal impurities are cations including any one or several of Al, Ti, Zr, Ca, and Ba.

4. A 188 during the preparation process of Re 186 recycling method of W target material It is characterized in that In step (2), the pH of the filtrate is adjusted to be less than or equal to 2 for precipitation, followed by standing and filtration to obtain a precipitate containing 186 W; the temperature during the precipitation operation process is 10°C to 60°C.

5. According to claim 1, a 188 during the preparation process of Re 186 recycling method of W target material It is characterized in that in step (3), the precipitate is placed in an oven at 60°C to 120°C for constant-temperature drying, and after drying is completed, it is ground into powder.

6. According to claim 1, a 188 During the preparation process of Re 186 Method for recycling W target material It is characterized in that in step (3), the temperature for high-temperature roasting is 200°C to 500°C, and the roasting time is 2 h to 4 h.

7. A 188 method for recycling W target material during the preparation process of 186 Re, according to claim 1 It is characterized in that containing 186 The waste liquid containing W is the filler dissolution liquid of a gel-type or irradiation-type tungsten-rhenium generator, or the column desorption liquid of a chromatographic tungsten-rhenium generator, or the supernatant produced during the synthesis of the column filling material of a gel-type tungsten-rhenium generator.

8. A 188 during the preparation process of Re 186 method for recycling W target material It is characterized in that the column packing material of the gel-type and irradiation-type tungsten-rhenium generator includes one of titanium tungstate, zirconium tungstate, ZrSiW gel, tungsten-containing binary gel material, and tungsten-containing binary gel material; using a dissolving reagent to dissolve the column packing material to obtain a dissolved solution; the dissolving reagent includes any one or several of sodium hydroxide, hydrochloric acid, sulfuric acid, and nitric acid.

9. A 188 during the preparation process of Re 186 recycling method of W target material It is characterized in that the column packing material of the chromatographic-type tungsten-rhenium generator includes any one of acidic alumina, Dowex 1X8 cation resin, and organic phosphorus resin; pumping a desorbing agent into the upper end of the column of the chromatographic-type tungsten-rhenium generator to obtain a desorbed solution; the desorbing agent includes any one or several of sodium hydroxide, sodium carbonate, sodium sulfate, sodium chloride, nitric acid, and hydrochloric acid; the concentration of the desorbing agent is 0.1 to 8 mol / L, the desorbing temperature is 15 to 30°C, and the flow rate of the desorbing agent onto the column is 1 - 3 mL / min.

10. A 188 during the preparation process of Re 186 recycling method of W target material It is characterized in that the supernatant liquid generated during the synthesis of the column packing material of the gel-type tungsten-rhenium generator is the supernatant liquid generated during the synthesis of any one of titanium tungstate, zirconium tungstate, ZrSiW gel, tungsten-containing binary gel material, and tungsten-containing ternary gel material.

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