CN114822976B - Preparation method of iron-arsenic compound and iron-based superconductor - Google Patents
Preparation method of iron-arsenic compound and iron-based superconductor Download PDFInfo
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- CN114822976B CN114822976B CN202210477572.3A CN202210477572A CN114822976B CN 114822976 B CN114822976 B CN 114822976B CN 202210477572 A CN202210477572 A CN 202210477572A CN 114822976 B CN114822976 B CN 114822976B
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 111
- VETKVGYBAMGARK-UHFFFAOYSA-N arsanylidyneiron Chemical compound [As]#[Fe] VETKVGYBAMGARK-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 238000002360 preparation method Methods 0.000 title claims abstract description 31
- 229910052742 iron Inorganic materials 0.000 title claims description 26
- 239000002887 superconductor Substances 0.000 title claims description 25
- 239000000843 powder Substances 0.000 claims abstract description 66
- 239000002253 acid Substances 0.000 claims abstract description 60
- 238000001354 calcination Methods 0.000 claims abstract description 54
- 238000005406 washing Methods 0.000 claims abstract description 50
- 239000011812 mixed powder Substances 0.000 claims abstract description 41
- 229910052785 arsenic Inorganic materials 0.000 claims abstract description 27
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000003825 pressing Methods 0.000 claims abstract description 18
- 239000012298 atmosphere Substances 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 238000000227 grinding Methods 0.000 claims abstract description 10
- 238000005554 pickling Methods 0.000 claims description 45
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 26
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical group Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 16
- 229910052786 argon Inorganic materials 0.000 claims description 13
- 230000000630 rising effect Effects 0.000 claims description 12
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical group O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 239000002243 precursor Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 11
- 150000001875 compounds Chemical class 0.000 abstract description 3
- 230000002194 synthesizing effect Effects 0.000 abstract 1
- 239000012300 argon atmosphere Substances 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 15
- 239000010453 quartz Substances 0.000 description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 15
- 238000001035 drying Methods 0.000 description 11
- 238000007789 sealing Methods 0.000 description 11
- 238000002441 X-ray diffraction Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 230000010355 oscillation Effects 0.000 description 10
- 239000012535 impurity Substances 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 6
- 238000000967 suction filtration Methods 0.000 description 6
- 238000011049 filling Methods 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000000465 moulding Methods 0.000 description 3
- 238000003746 solid phase reaction Methods 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 150000001495 arsenic compounds Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 229940093920 gynecological arsenic compound Drugs 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G28/00—Compounds of arsenic
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
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- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Iron (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention provides a preparation method of an iron-arsenic compound, which comprises the following steps: s1, mixing iron powder and arsenic powder according to a molar ratio of 1-2:1-2 under the protection of inert atmosphere; s2, after the mixing is completed, pressing treatment is carried out under the protection of inert atmosphere; s3, calcining the formed mixed powder at 600-1000 ℃ under negative pressure to obtain an iron-arsenic block; s4, grinding the iron-arsenic block to obtain iron-arsenic powder; and then carrying out acid washing treatment with the concentration of 0.5-2mol/L and acid washing treatment with the concentration of 0.5-1mol/L on the iron-arsenic powder in sequence to obtain the iron-arsenic compound. The method for preparing different iron-arsenic pure compound powder quickly, efficiently and at low cost can obtain three pure iron-arsenic compounds, thereby being used for synthesizing iron-arsenic based high-purity materials.
Description
Technical Field
The invention relates to the technical field of iron-based superconductors, in particular to a preparation method of an iron-arsenic compound and an iron-based superconductor.
Background
As the second largest high temperature superconductor following the copper-based superconductor, the advent of iron-based superconductors has been of great significance and value for the development of high temperature superconducting materials. Because of the characteristics of iron-based superconductors, such as higher superconducting transition temperature, higher upper critical magnetic field (Hca > 100T), higher critical current density (J >106A/cm 2), and the like, people are paying attention to the possibility of the iron-based superconductors in practical application, and particularly have good application prospects in the field of superconducting wires. The current carrying capacity of the superconducting wire is nearly hundreds of times that of a common wire due to the infinite current carrying capacity of the superconducting wire, and the energy loss in the process of conveying electric energy can be greatly reduced due to the complete diamagnetism of the superconducting wire, so that the transmission efficiency is improved.
In 2 months 2008, the professor Hideo Hosono of Tokyo university of industry in Japan discovered for the first time that fluorine doped iron-based high temperature superconducting material LaOFeAs with a superconducting critical temperature of 26K was found, which bombards the whole condensed physical world. Shortly, chen Xianhui of the national laboratory of China, large microscale, teaches the laboratory in SmFeAsO 1-x F x The first time an iron-arsenic-based superconductor with a critical temperature exceeding 40K was obtained, the critical transition temperature of the superconductor reached 43K, and then CeFeAsO was found by the subject group Wang Nanlin of the Chinese academy of sciences 1-x F x The material has a transition temperature of 41K.
For iron-based superconducting material preparation, precursor LnAs (ln=la, pr, fe, etc.) is generally synthesized first: uniformly mixing high-purity La, pr and Fe powder with high-purity As powder respectively, molding and sintering in a vacuum-pumped quartz tube; then mixing other elements required by the ReFeAsO according to the mol number required by the chemical formula, and sintering the mixed elements into the iron-based superconductor material in a sealed quartz tube. Therefore, in the process of preparing the iron-based superconductor material, the preparation of the precursor is important.
The synthesis of iron and arsenic compounds is usually carried out by solid phase reaction at high temperature and high pressure. Nao Takeshita, the institute of advanced Industrial science and technology, of Japan, synthesizes high quality FeAs, feAs using High Pressure (HP) method at about 2GPa and 1200K 2 And Fe (Fe) 2 As polycrystal samples, the prepared iron-arsenic compound is very compact and uniform. However, this method requires too high pressure and temperature, and the corresponding cost is also high.
In view of the above, it is necessary to provide a method for producing an iron-arsenic compound and an iron-based superconductor, which solves or at least alleviates the above-mentioned technical drawbacks, thereby obtaining an iron-arsenic compound and an iron-based superconductor in high purity at a low cost.
Disclosure of Invention
The invention aims to provide a preparation method of an iron-arsenic compound and an iron-based superconductor, and aims to solve the technical problems of high preparation cost and low purity in the prior art.
In order to achieve the above object, the present invention provides a method for preparing an iron-arsenic compound, comprising the steps of:
s1, mixing iron powder and arsenic powder according to a molar ratio of 1-2:1-2 under the protection of inert atmosphere to obtain mixed powder;
wherein the purities of the iron powder and the arsenic powder are more than or equal to 98 percent;
s2, carrying out pressing treatment on the mixed powder under the protection of inert atmosphere to obtain molded mixed powder;
s3, calcining the formed mixed powder to obtain an iron-arsenic block;
the calcination temperature of the calcination treatment is 600-1000 ℃, the temperature rise rate of the calcination treatment is 5-20 ℃, the calcination time of the calcination treatment is 4-6h, and the calcination treatment is carried out under the condition of negative pressure;
s4, grinding the iron-arsenic block to obtain iron-arsenic powder; then sequentially carrying out primary acid washing treatment and secondary acid washing treatment on the iron-arsenic powder to obtain the iron-arsenic compound, wherein the iron-arsenic compound comprises FeAs and FeAs 2 And Fe (Fe) 2 One or more of As;
wherein the concentration of the acid solution adopted in the primary acid washing treatment is 0.5-2mol/L; the concentration of the acid solution adopted in the secondary acid washing treatment is 0.5-1mol/L.
Further, in the step S1, the mixing time period of the iron powder and the arsenic powder is 24-32 hours.
Further, the inert atmosphere in the step S1 and the step S2 includes nitrogen and/or argon.
Further, the pressing treatment adopts a pressing pressure of 20-30MPa.
Further, in the step S3, the vacuum degree of the negative pressure is not higher than 10 -3 Pa。
Further, the acid solution adopted in the primary acid washing treatment is hydrochloric acid solution, and the acid solution adopted in the secondary acid washing treatment is nitric acid solution;
in the processes of the primary acid washing treatment and the secondary acid washing treatment, the solid-to-liquid ratio of the iron-arsenic powder to the acid solution is 1g:10-20ml;
the pickling time length adopted by the primary pickling treatment and the secondary pickling treatment is 18-24 hours.
Further, when the preparation method meets one of the first preset conditions, the iron-arsenic compound comprises FeAs;
when the preparation method completely accords with the first preset condition, the iron-arsenic compound is FeAs;
wherein the first preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 1:1;
the calcination temperature of the calcination treatment is 800-900 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts the pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-1mol/L.
Further, when the preparation method meets one of the second preset conditions, the iron-arsenic compound comprises FeAs 2 ；
When the preparation method completely meets the second preset condition, the iron-arsenic compound is FeAs 2 ；
Wherein the second preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 1:2;
the calcination temperature of the calcination treatment is 600-800 ℃, and the temperature rising rate of the calcination treatment is 15-20 ℃;
the primary pickling treatment adopts the pickling concentration of 0.5-1mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-0.8mol/L.
Further, when the preparation method meets one of the third preset conditions, the iron-arsenic compound includes Fe 2 As；
When the preparation method is completeWhen the third preset condition is met, the iron-arsenic compound is Fe 2 As；
Wherein the third preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 2:1;
the calcination temperature of the calcination treatment is 900-1000 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts the pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-1mol/L.
The invention also provides a preparation method of the iron-based superconductor, which adopts the preparation method of the high-purity iron-arsenic compound as described in any one of the above to prepare the iron-arsenic compound, and then uses the iron-arsenic compound as a precursor to prepare the iron-based superconductor.
Compared with the prior art, the invention has at least the following advantages:
the invention can obtain high-purity iron-arsenic compound with low cost, and can obtain FeAs with high purity, no impurity phase and high crystallinity at 600-1000 DEG C 2 And Fe (Fe) 2 As powder, and may not depend on a high-pressure environment. In addition, the invention carries out pressing treatment, specific temperature rising rate and acid washing with specific concentration twice, and can further ensure FeAs and FeAs under the calcination condition of 600-1000 DEG C 2 And Fe (Fe) 2 Purity of As.
The iron-arsenic compound prepared by the method can be used as an iron-based superconductor precursor on one hand, and the purity of the iron-arsenic compound is improved; on the other hand, the iron-arsenic compound prepared by the invention is purer, so that the iron-arsenic compound can be researched into deeper physical properties of a system. Specifically, the three iron-arsenic compounds prepared by the preparation method are all black brown in appearance, high in purity, free of generation of impurity phases and good in crystallinity.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an XRD pattern of pure FeAs powder obtained in example 1 of the present invention;
FIG. 2 shows the purified FeAs obtained in example 2 of the present invention 2 XRD pattern of powder;
FIG. 3 shows pure Fe obtained in example 3 of the present invention 2 XRD patterns of As powder;
FIG. 4 is an XRD pattern of FeAs-containing powder obtained in comparative example 1 of the present invention;
FIG. 5 shows the FeAs-containing material obtained in comparative example 2 of the present invention 2 XRD pattern of powder.
The achievement of the object, functional features and advantages of the present invention will be further described with reference to the drawings in connection with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention.
Moreover, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the embodiments, and when the technical solutions are contradictory or cannot be implemented, it should be considered that the combination of the technical solutions does not exist, and is not within the scope of protection claimed by the present invention.
Where numerical ranges are provided in the examples, it is understood that unless otherwise stated herein, both endpoints of each numerical range and any number between the two endpoints are significant both in the numerical range. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs and to which this invention belongs, and any method, apparatus, or material of the prior art similar or equivalent to the methods, apparatus, or materials described in the examples of this invention may be used to practice the invention.
The invention provides a preparation method of a high-purity iron-arsenic compound, which comprises the following steps:
s1, mixing iron powder and arsenic powder according to a molar ratio of 1-2:1-2 under the protection of inert atmosphere to obtain mixed powder.
Wherein the purities of the iron powder and the arsenic powder are more than or equal to 98 percent; the molar ratio of the iron powder to the arsenic powder can be specifically 1:1, 1:2 and 2:1; the mixing of the iron powder and the arsenic powder may be performed in a volumetric flask; the mixing time of the iron powder and the arsenic powder is 24-32h.
And S2, carrying out pressing treatment on the mixed powder under the protection of inert atmosphere to obtain molded mixed powder, wherein the molded mixed powder is generally powder compacted into blocks.
Wherein the inert atmosphere used in the step S1 and the step S2 may be nitrogen and/or argon.
The pressing pressure adopted in the pressing treatment is 20-30MPa, and the pressing duration is preferably not less than 20min. It should be understood that only at a specific compaction pressure, the solid phase reaction that occurs during the subsequent calcination process is ensured. When the pressing pressure is too low, the block is not formed, which is disadvantageous for the subsequent heat treatment (calcination treatment).
And S3, calcining the formed mixed powder to obtain an iron-arsenic block.
Wherein the calcination temperature of the calcination treatment is 600-1000 ℃, the temperature rising rate of the calcination treatment is 5-20 ℃, and the calcination time of the calcination treatment is 4-6h.
The calcination treatment is carried out under the condition of negative pressure; preferably, the vacuum degree of the negative pressure is not higher than 10 -3 Pa, can be generally 10 -3 Pa. The formation process of the negative pressure condition can be as follows: packaging the formed mixed powder into a quartz tube, and vacuum sealing the tube to obtain a quartz tubeAnd the molded mixed powder can be calcined under a specific vacuum degree.
S4, grinding the iron-arsenic block to obtain iron-arsenic powder; then sequentially carrying out primary acid washing treatment and secondary acid washing treatment on the iron-arsenic powder to obtain high-purity, impurity-free and high-crystallinity iron-arsenic compound powder, wherein the iron-arsenic compound comprises FeAs and FeAs 2 And Fe (Fe) 2 One or more of As. Thus, under the scheme of the embodiment, the invention can obtain pure FeAs and FeAs 2 And Fe (Fe) 2 As, the cost can be reduced, and the target product can be obtained rapidly.
After the calcination treatment is completed, the product obtained after the calcination is cooled to room temperature along with a furnace, and then the grinding treatment can be performed.
The concentration of the acid solution adopted in the primary acid washing treatment is 0.5-2mol/L; after the primary acid washing treatment, the iron-arsenic powder is required to be subjected to suction filtration and drying.
The concentration of the acid solution adopted in the secondary acid washing treatment is 0.5-1mol/L; after the secondary acid washing treatment, the iron and arsenic powder is required to be washed and dried.
The acid solution adopted in the primary acid washing treatment can be hydrochloric acid solution, and the acid solution adopted in the secondary acid washing treatment can be nitric acid solution; in the processes of the primary acid washing treatment and the secondary acid washing treatment, the solid-to-liquid ratio of the iron-arsenic powder to the acid solution can be 1g:10-20ml; the pickling duration of the primary pickling treatment and the secondary pickling treatment can be 18-24 hours.
It should be understood that in the above embodiments, the operations of mixing for a long time, tabletting (compression molding) under a specific pressure, etc. can ensure the solid phase reaction, and provide a basis for reducing the temperature and the pressure. In addition, by acid washing twice, the possibly existing impurity phases can be washed away under the condition of ensuring the integrity of the compound. Thus, the synergy between the steps in the above embodiments can obtain the iron-arsenic compound powder with high purity and high crystallinity.
In addition, it should be noted that:
1. as an illustration of FeAs production
When the preparation method meets one of the first preset conditions, the iron-arsenic compound comprises FeAs;
when the preparation method completely meets the first preset condition, the iron-arsenic compound is pure FeAs, and Fe: as atomic ratio can reach 1.009:1. It should be noted that FeAs herein means FeAs is extremely high in purity, contains few other substances, and Fe: the atomic ratio of As is approximately 1:1.
Wherein the first preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 1:1;
the calcination temperature of the calcination treatment is 800-900 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts the pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-1mol/L.
2. As a pair FeAs 2 Description of the preparation
When the preparation method meets one of the second preset conditions, the iron-arsenic compound comprises FeAs 2 ；
When the preparation method completely meets the second preset condition, the iron-arsenic compound is pure FeAs 2 Fe: as atomic ratio can reach 1:1.981. It should be noted that the FeAs herein 2 Refers to FeAs 2 The purity of (2) is extremely high, other substances are contained very little, and Fe: the atomic ratio of As is approximately 1:2.
Wherein the second preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 1:2;
the calcination temperature of the calcination treatment is 600-800 ℃, and the temperature rising rate of the calcination treatment is 15-20 ℃;
the primary pickling treatment adopts the pickling concentration of 0.5-1mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-0.8mol/L.
3. As a pair of Fe 2 Description of As preparation
When the preparation method meets one of the third preset conditions, the iron-arsenic compound comprises Fe 2 As；
When the preparation method completely meets the third preset condition, the iron-arsenic compound is pure Fe 2 As, its Fe: as atomic ratio can reach 1.85:1. It is to be noted that Fe herein 2 As means Fe 2 As is extremely high in purity, contains few other substances, and Fe: the atomic ratio of As is approximately 2:1.
Wherein the third preset condition includes one or more of the following conditions:
the molar ratio of the iron powder to the arsenic powder is 2:1;
the calcination temperature of the calcination treatment is 900-1000 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts the pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-1mol/L.
Based on the iron-arsenic compound, the invention also provides a preparation method of the iron-based superconductor, which adopts the preparation method of the high-purity iron-arsenic compound as described in any one of the above to prepare the iron-arsenic compound, and then uses the iron-arsenic compound as a precursor to prepare the iron-based superconductor.
Taking BaFeCoAs as an example, the process for preparing an iron-based superconductor from the iron-arsenic compound may be: the pure FeAs compound and other elements required by BaFeCoAs are fully ground and mixed according to the mol number required by chemistry, and then sintered into the iron-based superconductor material BaFeCoAs in a sealed quartz tube.
Example 1:
1. iron powder and arsenic powder with the purity of 98% are adopted, the mixture is put into a volumetric flask after being prepared in a glove box with the protection of argon atmosphere and the molar ratio of 1:1, and then the mixture is turned over and oscillated for 24 hours under the protection of argon so as to obtain uniformly mixed powder;
2. filling the mixed powder in the step 1 into a mould in a glove box protected by argon atmosphere, and then fillingPutting the mould into a large sample bag for sealing; taking the sample bag out of the glove box, and then pressing the die sleeved with the sample bag and filled with the mixed powder under 20Mpa and maintaining the pressure for 20 minutes; after the mixed powder is pressed and molded, the mixed powder is packaged into a quartz tube in a glove box protected by argon atmosphere, and is vacuumized until the vacuum degree is 10 -3 The pressure of Pa atmospheric pressure is high Wen Huoqiang, and the quartz tube is sealed; after vacuum tube sealing, heat treatment is carried out in a tube furnace under the circulation of argon protective atmosphere, and the tube furnace is heated to 800 ℃ at a heating rate of 10 ℃/min and then is insulated for 4 hours; after the heat treatment is finished, an iron-arsenic block body is obtained, and is cooled to room temperature along with a furnace;
3. grinding the iron-arsenic block obtained in the step 2 into powder, carrying out two times of acid washing according to the solid-to-liquid ratio of 1g to 20ml, carrying out 18h oscillation acid washing in 1mol/L hydrochloric acid, drying at 60 ℃ for 12h after suction filtration, carrying out 18h oscillation acid washing in 1mol/L nitric acid, and drying at 60 ℃ for 12h after water washing, thereby obtaining pure FeAs powder with black brown appearance, high purity, no impurity phase and high crystallinity.
As shown in fig. 1, the XRD pattern of the sample (pure FeAs powder) has no diffraction peak of impurity phase, and the peak intensity and peak position are matched with those of the standard PDF card of FeAs, so that the peak is sharp, five-broad, and the crystallinity is good.
Example 2:
1. iron powder and arsenic powder with the purity of 98% are adopted, the mixture is put into a volumetric flask in a glove box protected by argon atmosphere at a molar ratio of 1:2, and then the mixture is turned over and oscillated for 24 hours under the protection of argon so as to obtain uniformly mixed powder;
2. filling the mixed powder in the step 1 into a mould in a glove box protected by argon atmosphere, then putting the mould into a large sample bag for sealing, taking the sample bag out of the glove box, and then pressing the mould which is sleeved with the sample bag and is filled with the mixed powder under 30Mpa and maintaining the pressure for 20 minutes; after the mixed powder is pressed and molded, the mixed powder is packaged into a quartz tube in a glove box protected by argon atmosphere, and is vacuumized until the vacuum degree is 10 -3 The pressure of Pa atmospheric pressure is high Wen Huoqiang, and the quartz tube is sealed; after vacuum sealing, heat treatment is carried out in a tube furnace under the circulation of argon protective atmosphere, specifically 20 percentHeating to 600 ℃ at the temperature rising rate of the temperature per minute, and then preserving heat for 6 hours; after the heat treatment is finished, an iron-arsenic block body is obtained, and is cooled to room temperature along with a furnace;
3. grinding the iron-arsenic block obtained in the step 2 into powder, carrying out two times of acid washing according to the solid-to-liquid ratio of 1g to 20ml, carrying out 18h oscillation acid washing in 1mol/L hydrochloric acid, drying at 60 ℃ for 12h after suction filtration, carrying out 18h oscillation acid washing in 0.8mol/L nitric acid, and drying at 60 ℃ for 12h after water washing to obtain the pure FeAs with black brown appearance, high purity, no impurity phase and high crystallinity 2 And (3) powder.
As shown in FIG. 2, the samples (purified FeAs 2 Powder) diffraction peak without impurity phase in XRD pattern, peak intensity and peak position and FeAs 2 The standard PDF card is matched, the peak is sharp, the width is five, and the crystallinity is good.
Example 3:
1. iron powder and arsenic powder with the purity of 98% are adopted, the mixture is put into a volumetric flask in a glove box protected by argon atmosphere at a molar ratio of 2:1, and then the mixture is turned over and oscillated for 24 hours under the protection of argon so as to obtain uniformly mixed powder;
2. filling the mixed powder in the step 1 into a mould in a glove box protected by argon atmosphere, then putting the mould into a large sample bag for sealing, taking the sample bag out of the glove box, and then pressing the mould which is sleeved with the sample bag and is filled with the mixed powder under 20Mpa for molding and maintaining the pressure for 20 minutes; after the mixed powder is pressed and molded, the mixed powder is packaged into a quartz tube in a glove box protected by argon atmosphere, and is vacuumized until the vacuum degree is 10 -3 The pressure of Pa atmospheric pressure is high Wen Huoqiang, and the quartz tube is sealed; after vacuum tube sealing, heat treatment is carried out in a tube furnace under the circulation of argon protective atmosphere, and the tube furnace is heated to 900 ℃ at a heating rate of 10 ℃/min and then is insulated for 4 hours; after the heat treatment is finished, an iron-arsenic block body is obtained, and is cooled to room temperature along with a furnace;
3. grinding the iron-arsenic block obtained in the step 2 into powder, carrying out two times of acid washing according to the solid-to-liquid ratio of 1g to 20ml, carrying out 18h oscillation acid washing in 2mol/L hydrochloric acid, drying at 60 ℃ for 12h after suction filtration, carrying out 18h oscillation acid washing in 1mol/L nitric acid, and drying at 60 ℃ for 12h after water washing to obtain the iron-arsenic blockCan obtain pure Fe with black brown appearance, high purity, no impurity phase and high crystallinity 2 As powder.
As shown in FIG. 3, the sample (pure Fe 2 As powder) diffraction peak without impurity phase in XRD pattern, peak intensity and peak position and Fe 2 As standard PDF card is matched, the peak is sharp, the width is five, and the crystallinity is good.
Example 4
The elemental content of the pure iron-arsenic compounds obtained in examples 1 to 3 was determined by chemical titration:
comparative example 1:
1. iron powder and arsenic powder with the purity of 98% are adopted, the mixture is put into a volumetric flask in a glove box protected by argon atmosphere at a molar ratio of 1:1, and then the mixture is turned over and oscillated for 24 hours under the protection of argon so as to obtain uniformly mixed powder;
2. filling the mixed powder in the step 1 into a mould in a glove box protected by argon atmosphere, then putting the mould into a large sample bag for sealing, taking the sample bag out of the glove box, and then pressing the mould which is sleeved with the sample bag and is filled with the mixed powder under 20Mpa for molding and maintaining the pressure for 20 minutes; after the mixed powder is pressed and molded, the mixed powder is packaged into a quartz tube in a glove box protected by argon atmosphere, and is vacuumized until the vacuum degree is 10 -3 The pressure of Pa atmospheric pressure is high Wen Huoqiang, and the quartz tube is sealed; after vacuum tube sealing, heat treatment is carried out in a tube furnace under the circulation of argon protective atmosphere, and the tube furnace is heated to 950 ℃ at a heating rate of 10 ℃/min and then is insulated for 4 hours; after the heat treatment is finished, an iron-arsenic block body is obtained, and is cooled to room temperature along with a furnace;
3. grinding the iron-arsenic block obtained in the step 2 into powder, carrying out two times of acid washing according to the solid-to-liquid ratio of 1g to 20mL, carrying out 18h oscillation acid washing in 1mol/L hydrochloric acid, drying at 60 ℃ for 12h after suction filtration, carrying out 18h oscillation acid washing in 1mol/L nitric acid, and drying at 60 ℃ for 12h after water washing to obtain FeAs-containing powder.
The sample is shown in FIG. 4, in which Fe is present in addition to FeAs in the XRD pattern of the sample (powder containing FeAs) 2 As, due to the fact that the temperature is too high to 950 ℃, part of FeAs is dearsenified to Fe 2 As。
Comparative example 2:
1. iron powder and arsenic powder with the purity of 98% are adopted, the mixture is put into a volumetric flask in a glove box protected by argon atmosphere at a molar ratio of 1:2, and then the mixture is turned over and oscillated for 24 hours under the protection of argon so as to obtain uniformly mixed powder;
2. filling the mixed powder in the step 1 into a mould in a glove box protected by argon atmosphere, then putting the mould into a large sample bag for sealing, taking the sample bag out of the glove box, then pressing the mould which is sleeved with the sample bag and filled with the mixed powder under 30Mpa for 20 minutes, packaging the mixed powder into a quartz tube in the glove box protected by argon atmosphere after the mixed powder is pressed and molded, and vacuumizing to a vacuum degree of 10 -3 The pressure of Pa atmospheric pressure is high Wen Huoqiang, and the quartz tube is sealed; after vacuum tube sealing, heat treatment is carried out in a tube furnace under the circulation of argon protective atmosphere, and the tube furnace is heated to 850 ℃ at a heating rate of 20 ℃/min and then is insulated for 6 hours; after the heat treatment is finished, an iron-arsenic block body is obtained, and is cooled to room temperature along with a furnace;
3. grinding the iron-arsenic block obtained in the step 2 into powder, carrying out two times of acid washing according to the solid-to-liquid ratio of 1g to 20mL, carrying out 18h oscillation acid washing in 1mol/L hydrochloric acid, drying at 60 ℃ for 12h after suction filtration, carrying out 18h oscillation acid washing in 0.8mol/L nitric acid, and drying at 60 ℃ for 12h after water washing to obtain FeAs-containing iron-arsenic 2 Is a powder of (1);
the sample is shown in FIG. 5, the sample (FeAs-containing 2 Powder of (2) except FeAs in XRD pattern 2 In addition, feAs are present, due to the fact that the temperature is too high to 850 ℃, part of the FeAs 2 Dearsenification to FeAs occurs.
In the above technical solutions of the present invention, the above is only a preferred embodiment of the present invention, and the patent scope of the present invention is not limited thereby, and the above comparative examples are mainly used to highlight the obtaining manner of pure iron-arsenic compounds, and cannot negate the improvement of the present invention in the comparative examples. All the equivalent structural changes made by the content of the specification and the drawings of the invention or the direct/indirect application in other related technical fields are included in the patent protection scope of the invention under the technical conception of the invention.
Claims (5)
1. A method for preparing an iron-arsenic compound, comprising the steps of:
s1, mixing iron powder and arsenic powder according to a molar ratio of 1-2:1-2 under the protection of inert atmosphere to obtain mixed powder; the purities of the iron powder and the arsenic powder are more than or equal to 98%, and the mixing time of the iron powder and the arsenic powder is 24-32h;
s2, carrying out pressing treatment on the mixed powder under the protection of inert atmosphere to obtain molded mixed powder; the pressing pressure adopted in the pressing treatment is 20-30MPa;
s3, calcining the formed mixed powder to obtain an iron-arsenic block;
the calcination temperature of the calcination treatment is 600-1000 ℃, the temperature rise rate of the calcination treatment is 5-20 ℃, the calcination time of the calcination treatment is 4-6h, and the calcination treatment is carried out under the condition of negative pressure;
s4, grinding the iron-arsenic block to obtain iron-arsenic powder; then sequentially carrying out primary acid washing treatment and secondary acid washing treatment on the iron-arsenic powder to obtain the iron-arsenic compound, wherein the iron-arsenic compound comprises FeAs and FeAs 2 And Fe (Fe) 2 One or more of As;
the concentration of the acid solution adopted in the primary acid washing treatment is 0.5-2mol/L, and the concentration of the acid solution adopted in the secondary acid washing treatment is 0.5-1mol/L; the pickling time length adopted by the primary pickling treatment and the secondary pickling treatment is 18-24 hours;
wherein,,
when the preparation method completely accords with a first preset condition, the iron-arsenic compound is FeAs; the first preset condition includes:
the molar ratio of the iron powder to the arsenic powder is 1:1;
the calcination temperature of the calcination treatment is 800-900 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts a pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts a pickling concentration of 0.5-1mol/L;
when the preparation method completely meets the second preset condition, the iron-arsenic compound is FeAs 2 The method comprises the steps of carrying out a first treatment on the surface of the The second preset condition includes:
the molar ratio of the iron powder to the arsenic powder is 1:2;
the calcination temperature of the calcination treatment is 600-800 ℃, and the temperature rising rate of the calcination treatment is 15-20 ℃;
the primary pickling treatment adopts the pickling concentration of 0.5-1mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-0.8mol/L;
when the preparation method completely accords with the third preset condition, the iron-arsenic compound is Fe 2 As; the third preset condition includes:
the molar ratio of the iron powder to the arsenic powder is 2:1;
the calcination temperature of the calcination treatment is 900-1000 ℃, and the temperature rising rate of the calcination treatment is 5-20 ℃;
the primary pickling treatment adopts the pickling concentration of 1-2mol/L, and the secondary pickling treatment adopts the pickling concentration of 0.5-1mol/L.
2. The method of claim 1, wherein the inert atmosphere in step S1 and step S2 comprises nitrogen and/or argon.
3. The method according to claim 1, wherein in the step S3, the degree of vacuum of the negative pressure is not higher than 10 -3 Pa。
4. The method according to claim 1, wherein the acid solution used in the primary acid washing treatment is a hydrochloric acid solution, and the acid solution used in the secondary acid washing treatment is a nitric acid solution;
in the processes of the primary acid washing treatment and the secondary acid washing treatment, the solid-to-liquid ratio of the iron-arsenic powder to the acid solution is 1g:10-20ml.
5. A method for producing an iron-based superconductor, characterized in that an iron-arsenic compound is produced by the method for producing an iron-arsenic compound according to any one of claims 1 to 4, and then the iron-arsenic compound is used as a precursor to produce an iron-based superconductor.
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