CN108383531B

CN108383531B - MgB doped with topological luminophores in heterogeneous phase2Base superconductor and method for producing same

Info

Publication number: CN108383531B
Application number: CN201810462942.XA
Authority: CN
Inventors: 赵晓鹏; 李勇波; 陈宏刚; 陈国维
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2018-05-15
Filing date: 2018-05-15
Publication date: 2021-02-19
Anticipated expiration: 2038-05-15
Also published as: CN108383531A

Abstract

The invention relates to MgB doped with heterogeneous phase of topological luminophor₂Superconductor and its preparing process, and method for changing MgB by doping topological luminophor₂The superconducting transition temperature of the base superconductor. The invention adopts a hydrothermal method to prepare three topological luminophores: micron sheet m-Y₂O₃:Eu³⁺Ag, nanosheet n-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺and/AgCl. Hetero-phase doped MgB prepared by ectopic doping method for topological luminophor₂A base superconductor. The change of the superconducting transition temperature of the doped sample is researched by changing factors such as the size of the dopant, the Ag content, the mass fraction of the dopant and the like. It was found in experiments that when n-Y is used₂O₃:Eu³⁺AgCl is used as a doping agent, and when the doping concentration is 1 percent, the doped MgB₂The transition temperature of the base superconductor is higher than that of corresponding pure MgB₂And (3) sampling.

Description

MgB doped with topological luminophores in heterogeneous phase2Base superconductor and method for producing same

Technical Field

The invention relates to MgB doped with heterogeneous phase of topological luminophor₂A base superconductor and a method of preparing the same, the intelligent super-structure superconductor has excellent characteristics such as simple preparation method and relatively high critical transition temperature.

Background

2001 MgB₂Is found to be superconducting. MgB₂Simple structure, easy preparation, and relatively high critical transition temperature (T)_C39.0K), these good properties make MgB₂Has great practical application prospect. Currently, a great challenge is how to further improve MgB₂T of_CFor this reason, a great deal of research work has been carried out, and various methods have been tried. However, to date, no effective method has been found to improve MgB₂The superconducting transition temperature of the material.

Recent studies have shown that doping luminescent materials is expected to increase the superconducting transition temperature of the material. Y is₂O₃:Eu³⁺Is an excellent rare earth luminescent material, has mature preparation process and good stability. Our group of recent studies has shown that the preparation of yttrium oxide into a topological emitter will further improve itselfThe electroluminescent property of (2). Therefore, based on the idea of the metamaterial, the doping of the topological emitter into the superconducting material by using a chemical doping method is expected to further improve the superconducting transition temperature of the material.

Disclosure of Invention

In view of the above situation, the invention opens up a new method, utilizes the idea of metamaterial, combines chemical doping and optical field excitation, directly dopes the topological luminous body material into the superconductor matrix, excites the topological luminous body material to generate electroluminescence under the action of an external electric field, and researches on MgB doped with the electroluminescent material₂Influence of superconducting properties. Prepares MgB doped with heterogeneous phase of topological luminophor₂Based intelligent super-structure superconductor, a topological illuminant heterogeneous phase doped MgB with high critical transition temperature is obtained by changing the size, content and Ag content of dopant and illumination condition to carry out contrast experiment₂A base intelligent super-structured superconductor.

The invention adopts a hydrothermal method to prepare micron sheets and nano sheets of the topological luminophor, and an ectopic sintering method to prepare MgB doped with heterogeneous phases of the topological luminophor₂A base superconductor. As described below:

(1) MgB doped with topological luminophores in heterogeneous phase₂The superconductor is prepared by a hydrothermal method to obtain three dopants: micron sheet m-Y₂O₃:Eu³⁺Ag, nanosheet n-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺/AgCl; preparation of MgB doped with different Ag contents and different mass fractions by ectopic doping method₂A base superconductor.

(2) A topologically illuminant heterophase doped MgB as claimed in claim 1₂A superconductor and its preparation method, characterized in that the topological emitter dopant is distributed in MgB₂MgB with different superconducting properties can be prepared by changing the content of Ag in the topological luminophor, the illumination condition and the mass fraction of the dopant around the superconductor particles₂A base superconductor.

(3) Heterogeneous phase doping of topological emitters according to (1) aboveMgB₂The preparation method of the superconductor and the topological luminous body dopant comprises the following steps: weigh 0.153g Y₂O₃And 0.012g Eu₂O₃Placing in a beaker, dropwise adding excessive concentrated hydrochloric acid into the beaker, heating in a fume hood at 70 ℃ until white transparent crystals are separated out, and drying for 2h to obtain a precursor; adding 4mL deionized water into one part of the precursor, slowly dropping ammonium oxalate solution, vigorously stirring in water bath at 2 deg.C for 30min, and adding a certain amount of AgNO₃Continuously stirring for 30min, adjusting the pH to 9-10 by using a NaOH (4mol/L) solution, and continuously stirring for 30min to obtain a final mixed solution A; another part of the precursor is added with 24mL of benzyl alcohol, then 4mL of octylamine is slowly dropped into the mixture, the mixture is stirred for 1 hour, and a certain amount of AgNO is added₃Continuously stirring for 1h to obtain a final mixed solution B; respectively transferring the mixed solution A, B into a reaction kettle for hydrothermal reaction at 160 ℃ for 24h, centrifuging, washing and drying the resultant, and then putting the resultant into a tube furnace for high-temperature calcination at 800 ℃ for 2h to obtain Y₂O₃:Eu³⁺AgCl, and obtaining another two dopants after illumination, wherein the two dopants are m-Y respectively₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺Ag, varying AgNO added₃The doping agents with different silver contents can be prepared by the content.

(4) MgB heterodoped with a topological emitter according to (1) above₂Based on superconductors, MgB₂The preparation method of the base superconductor comprises the following steps: weighing topological illuminant dopants with corresponding different mass fractions and ball-milled MgB₂Respectively placing the raw materials into two beakers, adding alcohol, performing ultrasonic treatment for 20min, stirring with a magnetic stirrer, and simultaneously dropwise adding dopant solution into MgB₂In solution; and continuously stirring the mixed solution for 10 minutes, performing ultrasonic treatment for 20 minutes, then transferring the mixed solution into a culture dish, drying the mixed solution into black powder in a vacuum drying oven at 60 ℃ for 4 hours, fully grinding the powder, tabletting the powder, keeping the pressure and the pressure maintaining time at 12-16MPa for 5-10 minutes, and keeping the temperature at 800 ℃ for 2 hours under the high-purity Ar atmosphere to obtain a corresponding doped sample.

The invention has the beneficial effects that based on the idea of metamaterial, the topological illuminant material is doped into MgB by chemical doping₂In the method, the good performances of the topological luminous body material such as strong electroluminescent performance are utilized to change the superconducting performance of the material, and a new method for improving MgB is developed₂The method of superconducting transition temperature experimentally prepares MgB doped with topological luminophor heterogeneous phase with high critical transition temperature₂Based on the intelligent super-structure superconductor, the method is also expected to be applied to improving the performance of other superconducting materials.

Drawings

FIG. 1 hydrothermal preparation of m-Y₂O₃:Eu³⁺/Ag、n-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺Flow diagram of/AgCl

FIG. 2.a dopant m-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺XRD pattern of/Ag

FIG. 2.b dopant m-Y₂O₃:Eu³⁺SEM image of/Ag

FIG. 2.c-d dopant n-Y₂O₃:Eu³⁺AFM diagram of/Ag

FIG. 3MgB₂And m-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺Ag doped MgB₂XRD pattern of superconductor

FIG. 4 example-pure MgB₂And Y₂O₃、Y₂O₃:Sm³⁺Doped MgB₂Normalized resistivity map of superconductor

FIG. 5 example two pure MgB₂And m-Y₂O₃:Eu³⁺Ag doped MgB₂Normalized resistivity map of superconductor

FIG. 6 example of three pure MgBs₂And n-Y₂O₃:Eu³⁺Ag doped MgB₂Normalized resistivity map of superconductor

FIG. 7 example four pure MgB₂And n-Y₂O₃:Eu³⁺AgCl doped MgB₂Normalized resistivity map of superconductor

Detailed Description

The invention adopts a hydrothermal method to prepare three topological luminous body dopants m-Y₂O₃:Eu³⁺/Ag、n-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺AgCl for preparing MgB doped with heterogeneous topological luminophores by using ex-situ method₂A base superconductor. The preparation process comprises the following steps:

(1) weigh 0.153g Y₂O₃And 0.012g Eu₂O₃Placing in a beaker, dropwise adding excessive concentrated hydrochloric acid into the beaker, heating in a fume hood at 70 ℃ until white transparent crystals are separated out, and drying for 2h to obtain a precursor; adding 4mL deionized water into one part of the precursor, slowly dropping ammonium oxalate solution, vigorously stirring in water bath at 2 deg.C for 30min, and adding a certain amount of AgNO₃Continuously stirring for 30min, adjusting the pH to 9-10 by using a NaOH (4mol/L) solution, and continuously stirring for 30min to obtain a final mixed solution A; another part of the precursor is added with 24mL of benzyl alcohol, then 4mL of octylamine is slowly dropped into the mixture, the mixture is stirred for 1 hour, and a certain amount of AgNO is added₃Continuously stirring for 1h to obtain a final mixed solution B; respectively transferring the mixed solution A, B into a reaction kettle for hydrothermal reaction at 160 ℃ for 24h, centrifuging, washing and drying the resultant, and then putting the resultant into a tube furnace for high-temperature calcination at 800 ℃ for 2h to obtain Y₂O₃:Eu³⁺AgCl, and obtaining another two dopants after illumination, wherein the two dopants are m-Y respectively₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺Ag, varying AgNO added₃The doping agents with different silver contents can be prepared by the content.

(2) Weighing topological illuminant dopants with corresponding different mass fractions and ball-milled MgB₂Respectively placing the raw materials into two beakers, adding alcohol, performing ultrasonic treatment for 20min, stirring with a magnetic stirrer, and simultaneously dropwise adding dopant solution into MgB₂In solution; continuously stirring the mixed solution for 10 minutes, performing ultrasonic treatment for 20 minutes, transferring the mixed solution into a culture dish, drying the mixed solution into black powder at 60 ℃ for 4 hours in a vacuum drying oven, fully grinding the powder, tabletting the powder, keeping the pressure and the pressure for 5-10 minutes at 12-16MPa, and keeping the temperature at 800 ℃ for 2 hours under the high-purity Ar atmosphere to obtain a corresponding doped sample。

(3) The local electric field generated by the applied current in the process of measuring the transition temperature is utilized to excite the dopant of the topological luminous body to carry out electroluminescence, and the four-probe method is adopted to measure the change of the resistance of the sample along with the temperature so as to determine the superconducting transition temperature of the sample.

The implementation process and material properties of the invention are illustrated by the examples and the attached drawings:

the first embodiment is as follows:

(1) preparation of non-electroluminescent doping agent Y by hydrothermal method₂O₃And Y₂O₃:Sm³⁺The preparation flow is shown in figure 1, and rare earth elements are not added or replaced by Sm in the preparation process correspondingly.

(2) Preparation of pure MgB by ectopic solid phase doping method₂And Y₂O₃、Y₂O₃:Sm³⁺Doped MgB₂Base superconductor (mass fraction 2.0%).

(3) The curve of the resistance of the sample as a function of temperature was measured by a four-probe method using a liquid helium cryogenic system from Advanced Research Systems, inc: as shown in fig. 4. As can be seen in FIG. 4, pure MgB₂The superconducting transition temperature of the sample is 38-38.6K. Doping 2.0 wt% of non-electroluminescent dopant Y₂O₃Or Y₂O₃:Sm³⁺Then, the superconducting transition temperatures are 35.4-36.2K and 35.8-36.6K, respectively. Compared with pure MgB₂Sample, doped with non-electroluminescent material Y₂O₃And Y₂O₃:Sm³⁺The superconducting transition temperature of the material is greatly reduced.

Example two:

(1) hydrothermal method for preparing micron sheet m-Y₂O₃:Eu³⁺Ag (the mass fraction of Ag is 1-8%): the preparation flow chart is shown in figure 1. Dopant m-Y₂O₃:Eu³⁺XRD and SEM images of/Ag are shown in FIGS. 2 a-b.

(2) Preparation of pure MgB by ectopic solid phase doping method₂And m-Y₂O₃:Eu³⁺Ag doped MgB₂The mass fraction of the doping agent is 2 percent.

(3) The phase analysis of the sample was performed using an X-ray diffractometer model X' Pert MPD PRO from Pasacaceae, the Netherlands, and the results are shown in FIG. 3. The test result shows that the pure MgB₂And m-Y₂O₃:Eu³⁺Ag doped MgB₂The main phase of the superconductor is MgB₂The phases, and all contain a small amount of MgO phase, which is mainly derived from the small amount of oxygen mixed from the environment during the preparation process. In addition, there is Y in the phase diagram of the doped sample₂O₃The presence of a phase. Meanwhile, due to the small content of Eu and Ag elements in the sample, no corresponding peak is observed in the phase diagram. The curve of the resistance of the sample as a function of temperature was measured by a four-probe method using a liquid helium cryogenic system from Advanced Research Systems, inc: as shown in fig. 5. As can be seen from the figure, the doping all lowered the superconducting transition temperature of the sample. For the doped samples: along with the increase of the content of Ag in the dopant, the superconducting transition temperature of the sample firstly increases and then decreases, and when the content of Ag is 5%, the superconducting transition temperature is the highest.

Example three:

(1) hydrothermal method for preparing nanosheet n-Y₂O₃:Eu³⁺Ag (the mass fraction of Ag is 5%): the preparation flow chart is shown in figure 1. Dopant n-Y₂O₃:Eu³⁺XRD and AFM patterns of/Ag are shown in FIG. 2a and FIGS. 2 c-d.

(2) Preparation of pure MgB by ectopic solid phase doping method₂And n-Y₂O₃:Eu³⁺Ag doped MgB₂The mass fraction of the doping agent is 0.1-2%.

(3) The phase analysis of the sample was performed using an X-ray diffractometer model X' Pert MPD PRO from Pasacaceae, the Netherlands, and the results are shown in FIG. 3. The test results were similar to example two: pure MgB₂And n-Y₂O₃:Eu³⁺Ag doped MgB₂The main phase of the superconductor is MgB₂Phases, both containing a small amount of MgO phase, and also Y in the phase diagram of the doped sample₂O₃The presence of a phase. Meanwhile, due to the small content of Eu and Ag elements in the sample, no corresponding peak is observed in the phase diagram. Utilizing AdvanceThe liquid helium cryogenic system from d Research Systems, Inc. measures the curve of the resistance of the sample as a function of temperature using a four-probe method: as shown in fig. 6. As can be seen from the figure, the doping lowers the superconducting transition temperature of the sample. For the doped samples: as the content of the dopant increases, the superconducting transition temperature of the sample generally shows a tendency of increasing and then decreasing, and when the content of the dopant is 0.5%, the superconducting transition temperature is as high as 37.6-38.4K and is relatively close to that of a pure sample.

Example four:

(1) hydrothermal preparation of n-Y₂O₃:Eu³⁺AgCl (mass fraction of AgCl is 1%): the preparation flow chart is shown in fig. 1, and the corresponding dopant is not irradiated with light.

(2) Preparation of pure MgB by ectopic solid phase doping method₂(particle size less than 2.5 μm) and n-Y₂O₃:Eu³⁺AgCl doped MgB₂The mass fraction of the doping agent is 0.5 percent of the base superconductor.

(3) The curve of the resistance of the sample as a function of temperature was measured by a four-probe method using a liquid helium cryogenic system from Advanced Research Systems, inc: as shown in fig. 7. As can be seen from the figure, pure MgB₂The superconducting transition temperature of the sample is 35.2-36.8K. The results show that MgB can be reduced although the ball milling time is increased₂Particle size, but also reduces pure MgB₂Superconducting transition temperature of the sample. MgB of this small size₂Is used as raw material and is doped with n-Y with the mass fraction of 0.5 percent₂O₃:Eu³⁺The result of AgCl shows that the temperature of the doped sample is raised to 36-37.6K.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the scope of the invention, which is defined by the appended claims and the description of the invention, and all such changes and modifications as fall within the scope of the invention.

Claims

1. MgB doped with topological luminophores in heterogeneous phase₂The superconductor is characterized in that three dopants are prepared by a hydrothermal method: micron sheet m-Y₂O₃:Eu³⁺Ag, nanosheet n-Y₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺/AgCl; preparation of MgB doped with different Ag contents and different mass fractions by ectopic doping method₂A base superconductor.

2.A topologically illuminant heterophase doped MgB as claimed in claim 1₂Base superconductor, characterized in that the topological emitter dopant is distributed in MgB₂MgB with different superconducting properties can be prepared by changing the content of Ag in the topological luminophor, the illumination condition and the mass fraction of the dopant around the superconductor particles₂A base superconductor.

3. A topologically illuminant heterophase doped MgB as claimed in claim 1₂A method of making a base superconductor comprising the steps of:

(1) weigh 0.153g Y₂O₃And 0.012g Eu₂O₃Placing in a beaker, dropwise adding excessive concentrated hydrochloric acid into the beaker, heating in a fume hood at 70 ℃ until white transparent crystals are separated out, and drying for 2h to obtain a precursor; adding 4mL deionized water into one part of the precursor, slowly dropping ammonium oxalate solution, vigorously stirring in water bath at 2 deg.C for 30min, and adding a certain amount of AgNO₃Continuously stirring for 30min, adjusting the pH to 9-10 by using a NaOH solution, and continuously stirring for 30min to obtain a final mixed solution A; another part of the precursor is added with 24mL of benzyl alcohol, then 4mL of octylamine is slowly dropped into the mixture, the mixture is stirred for 1 hour, and a certain amount of AgNO is added₃Continuously stirring for 1h to obtain a final mixed solution B; respectively transferring the mixed solution A, B into a reaction kettle for hydrothermal reaction at 160 ℃ for 24h, centrifuging, washing and drying the resultant, and then putting the resultant into a tube furnace for high-temperature calcination at 800 ℃ for 2h to obtain Y₂O₃:Eu³⁺AgCl, and obtaining another two dopants after illumination, wherein the two dopants are m-Y respectively₂O₃:Eu³⁺Ag and n-Y₂O₃:Eu³⁺Ag, varying AgNO added₃The doping agents with different silver contents can be prepared by the content.

(2) Weighing topological illuminant dopants with corresponding different mass fractions and ball-milled MgB₂Respectively placing the raw materials into two beakers, adding alcohol, performing ultrasonic treatment for 20min, stirring with a magnetic stirrer, and simultaneously dropwise adding dopant solution into MgB₂In solution; and continuously stirring the mixed solution for 10 minutes, performing ultrasonic treatment for 20 minutes, then transferring the mixed solution into a culture dish, drying the mixed solution into black powder in a vacuum drying oven at 60 ℃ for 4 hours, fully grinding the powder, tabletting the powder, keeping the pressure and the pressure maintaining time at 12-16MPa for 5-10 minutes, and keeping the temperature at 800 ℃ for 2 hours under the high-purity Ar atmosphere to obtain a corresponding doped sample.