WO2009124447A1

WO2009124447A1 - A high temperature superconductive material and the preparation method thereof

Info

Publication number: WO2009124447A1
Application number: PCT/CN2009/000084
Authority: WO
Inventors: 陈仙辉; 吴涛; 吴刚; 刘荣华; 陈红; 房岱峰
Original assignee: 中国科学技术大学
Priority date: 2008-04-11
Filing date: 2009-01-20
Publication date: 2009-10-15
Also published as: CN101265099A; CN101265099B

Abstract

A high temperature superconductive material with a formula of SmO_1-xF_xFeAs (wherein 0≤x≤0.4). Its Tc is 0-53K. Its preparation method comprises the following steps: Mix the high-purity Sm and As uniformly in an atmosphere with no oxygen and low moisture and then press them into chips; Anneal the chips at 500-650℃ for 3-10h in high vacuum and further anneal the chips at 800-950℃ for 5-10h and then cool them down to obtain the pre-product SmAs; Mix SmAs, high-purity SmF₃, Fe, Fe₂O₃ and As uniformly according to the specific ratio in an atmosphere with no oxygen and low moisture and then press them into pellets; Wrap the pellets into Ta foil and anneal them at 1000-1200℃ for 40-60h in high vacuum; Cool them down to room temperature and peel the Ta foil off to obtain the final product.

Description

一种高温超导材料及其制备方法 High-temperature superconducting material and preparation method thereof

技术领域 Technical field

本发明涉及一种超导材料及其制备方法，特别涉及一种高温超导材料及其制备方法，确切地说是一种化学式为 SmO^FxFeAs^Sx O^)高温超导材料及其制备方法。背景技术 The invention relates to a superconducting material and a preparation method thereof, in particular to a high-temperature superconducting material and a preparation method thereof, and more specifically to a high-temperature superconducting material with a chemical formula of SmO^FxFeAs^SxO^) and a preparation method thereof . Background technique

超导现象于 1911年由荷兰人纳斯教授发现，至今已有近百年的历史。当一种材料进入超导状态时，主要表现出两种特征现象：一个是零电阻现象，另一个是完全排,磁通现象。正是由于超导体具有以上两种特性，使其应用前景非常广泛，例如利用其零电阻特性可以制成强磁场线圈以提供强磁场，超导磁体的应用范围也很广泛，如在固体物理研究、高能物理、受控核聚变反应堆、发电机、电动机、变压器、磁流体发电机、电磁推进装置以及医学人体核磁共振成像装置等许多方面，而完全排磁通现象也已经应用于磁悬浮列车中。如此广泛的应用前景使得人们对其机理和应用的研究的热情空前高涨。但是，在超导材料的应用方面，传统超导体的临界温度都比较低（<23K )，这成为限制其应用的不利因素。而在超导理论方面，著名的 BCS超导理论也预言了超导体的临界温度不会超过 40Κ，这对于超导现象的应用无疑是雪上加霜。 Superconductivity was discovered by the Dutchman Professor Nas in 1911 and has a history of nearly a hundred years. When a material enters the superconducting state, it mainly exhibits two characteristic phenomena: one is a zero resistance phenomenon, and the other is a complete discharge, a magnetic flux phenomenon. Because superconductors have the above two characteristics, their application prospects are very broad. For example, their zero-resistance characteristics can be used to make strong magnetic field coils to provide strong magnetic fields. Superconducting magnets are also widely used, such as in solid state physics research. High-energy physics, controlled nuclear fusion reactors, generators, motors, transformers, magnetic fluid generators, electromagnetic propulsion devices, and medical human magnetic resonance imaging devices, and the full magnetic flux phenomenon has also been applied to maglev trains. Such broad application prospects have led to unprecedented enthusiasm for research on its mechanisms and applications. However, in the application of superconducting materials, the critical temperature of conventional superconductors is relatively low (<23K), which is a disadvantage for limiting its application. In terms of superconducting theory, the famous BCS superconducting theory also predicts that the critical temperature of a superconductor will not exceed 40 Κ, which is undoubtedly worse for the application of superconducting phenomena.

1986年，瑞士苏黎世 IBM研究室学者 J. G. Bednorz和 K. A. Muller共同发现高临界温度的铜氧化合物超导体，其超导温度达到 35K ( - 238°C ), 并且在随后的相关研究中发现在该类铜氧化合物材料中其超导温度最高可达到 130K ( -143°C ), 该温度已经突破了液氮温度（77K )。正是由于高温超导铜氧化合物的发现，使得人们再一次看到了"室温超导，，的可能性，并且其对传统的超导理论也带来巨大的冲击。高温超导铜氧化合物的发现到现在也已经有二十多年的历史了，到目前为止，该类材料是唯一的超导临界温度突破 40Κ的超导材料。但是其超导的机理仍然悬而未决，并且最大超导临界温度也停滞在 130K。现在，人们正在努力探索新的高温超导体，目的是进一步提高超导临界温度，并且为超导的机理研究带来更多的可用的信息。最近，东京工业大学界面研究中心教授细野秀雄等 2008年 2月 18日宣布，在含铁的氧磷族元素化合物（LaOFeAs)中发现了超导电性，其最高临界温度为 32K ( -24U 5°C )。这无疑又是一次对超导科学界的沖击，人们正期待在该类材料中能发现更高的超导临界材料。发明内容 In 1986, IBM laboratory researcher JG Bednorz and KA Muller of Zurich jointly discovered a high-temperature-temperature copper oxide superconductor with a superconducting temperature of 35K (-238°C), and found in such subsequent studies in this type of copper. The superconducting temperature of the oxygen compound material can reach 130K (-143 °C), which has exceeded the liquid nitrogen temperature (77K). It is precisely because of the discovery of high-temperature superconducting copper oxides that people once again see the possibility of "room temperature superconductivity, and it also has a huge impact on the traditional superconducting theory. High temperature superconducting copper oxide compounds It has been discovered for more than 20 years now. So far, this kind of material is the only superconducting material with a superconducting critical temperature exceeding 40 。. However, the mechanism of superconductivity is still pending, and the maximum superconducting critical temperature It is also stagnant at 130K. Now, efforts are being made to explore new high-temperature superconductors with the aim of further increasing the superconducting critical temperature and bringing more information available for the study of superconducting mechanisms. Recently, Professor Hiroshi Hideo of the Institute of Interface Research at Tokyo Institute of Technology announced on February 18, 2008 that superconductivity was found in iron-containing oxyphosphorus compound (LaOFeAs) with a maximum critical temperature of 32K (-24U 5). °C). This is undoubtedly another impact on the superconducting science community, and people are expecting to find higher superconducting critical materials in this class of materials. Summary of the invention

本发明借鉴 LaOFeAs这一超导材料，旨在提供一种超导临界温度（ Tc ) 更高的新的超导材料，所要解决的技术问题是遴选新的稀土元素取代镧（La ) 并进行掺杂，同时构建相应的制备方法。 The invention utilizes the superconducting material LaOFeAs to provide a new superconducting material with a higher superconducting critical temperature (Tc). The technical problem to be solved is to select a new rare earth element to replace lanthanum (La) and do it. Miscellaneous, at the same time construct the corresponding preparation method.

本发明所称的高温超导材料是化学式为 SmO^F_xFeAs所示的化合物，其临界超导温度 Tc为 0 ~ 53K, 式中 X取自 0〜0.4。 The high-temperature superconducting material referred to in the present invention is a compound represented by a chemical formula of SmO^F _x FeAs, and has a critical superconducting temperature Tc of 0 to 53 K, wherein X is from 0 to 0.4.

本高温超导材料的制备方法是先制备前驱物，再制备目标物，包括混合、焙烧和冷却，所述的前驱物为砷化钐（SmAs ), 取纯度 99.99%的 Sm粉和純度 99.99%的 As粉，在无氧和水分含量小于或等于 lppm的气氛中研磨混合均匀，压制成片置于容器中，然后在真空度小于或等于 10—³Pa 的条件下升温至 500〜650°C焙烧 3~10小时，再继续升温至 800〜950°C焙烧 5-10小时，最后冷却出料。用前驱物同三氟化钐（SmF₃ )、铁 ( Fe ), 砷 ( As )和氧化铁 ( Fe₂0₃ ) 制备目标物，具体方法是将 SmAs粉同纯度 99.99%的 SmF₃粉和纯度 98%的 Fe粉，纯度 99.99%的 As粉以及纯度 99%的 Fe₂0₃粉按比例在无氧和水分含量小于或等于 lppm的气氛中研磨混合均匀并压制成片，包覆钽（Ta )膜片后置于容器中，在真空度小于或等于 l(T³Pa 的条件下升温至 1000〜1200 C焙烧 40〜60小时，再降至室温，剥离 Ta膜便得到目标物。所述的按比例是指各原料的摩尔比，即 SmAs ： SmF₃ ： Fe ： Fe₂0₃ ： As= (l -x)/3 ： x/3 ： (l+2x)/3 ： (l-x)/3 :x/3 , 式中 X取自 0-0.4, 所述的升温和降温是按 l〜8°C/min的速率升温和降温，优选 2〜6 °C /min. The high-temperature superconducting material is prepared by first preparing a precursor, and then preparing a target, including mixing, calcining and cooling, wherein the precursor is arsenic arsenide (SmAs), and the purity of 99.99% Sm powder is 99.99%. as the powder, the oxygen and moisture content of less than or equal to lppm atmosphere polishing mixed and compressed into tablets in a container, and then under vacuum conditions of less than or equal to 10- ³ Pa warmed to 500~650 ° C After calcination for 3 to 10 hours, the temperature is further increased to 800 to 950 ° C for 5-10 hours, and finally the discharge is cooled. The target is prepared by using a precursor with lanthanum trifluoride (SmF ₃ ), iron (Fe), arsenic (As ) and iron oxide (Fe ₂ 0 ₃ ), in particular, by using SmAs powder with a purity of 99.99% SmF ₃ powder and Fe powder with a purity of 98%, As powder with a purity of 99.99%, and Fe ₂ 0 ₃ powder with a purity of 99% are ground and uniformly mixed in an atmosphere having an oxygen-free and moisture content of less than or equal to 1 ppm, and pressed into a sheet, coated with ruthenium ( Ta) The film is placed in a container and heated to 1000 to 1200 C under a vacuum of less than or equal to 1 (T ³ Pa for 40 to 60 hours, and then cooled to room temperature, and the Ta film is peeled off to obtain a target. The proportional ratio refers to the molar ratio of each raw material, that is, SmAs : SmF ₃ : Fe : Fe ₂ 0 ₃ : As = (l -x) / 3 : x / 3 : (l + 2x) / 3 : (lx) /3 : x / 3 , where X is taken from 0-0.4, the temperature rise and fall is to increase and decrease the temperature at a rate of l~8 ° C / min, preferably 2~6 ° C / min.

无氧条件是用惰性气体隔绝空气形成的，所述的惰性气体选自高纯的氩气或氦气或氮气或 C0₂气体。隔绝空气的作用是防止单质 Sm和 As的氧化，严格控制水分含量旨在防止 SmF₃的吸湿、潮解。包覆 Ta膜片旨在防止高温条件下容器物质（内壁）参与的不良反应。本材料用稀土 Sm取代 La, 并在氧位上掺杂氟离子，是除高温超导铜氧化合物系列之外，具有最高超导临界温度的、新型的铁砷系列高温超导材料。通过 Sm替换 La后超导临界温度 T_c从 28K显著提高到 53K， Sm(0,F)FeAs是目前铁砷系列高温超导材料中具有最高超导临界温度的材料,其超导临界温度为 53K, 这已经打破了 BCS理论预言常规超导体超导临界温度 T_c不可能超过 40K的理论值，同时它也大于具有最高超导临界温度 T_C=39K的非铜氧化合物超导体 MgB₂。同时此材料的优点是具有很高的临界温度以及很高的临界磁场，将具有比 MgB₂等材料更为广阔的应用前景。这还将有利于进一步帮助理解铜氧化合物高溫导体的物理机制以及强关联体系中的一些基本物理，为理论工作者提供了挑战和实猃题材。附图说明 The anaerobic condition is formed by isolating air with an inert gas selected from the group consisting of high purity argon or helium or nitrogen or CO ₂ gas. The role of air isolation is to prevent the oxidation of elemental Sm and As. Strict control of moisture content is intended to prevent moisture absorption and deliquescence of SmF ₃ . The Ta film is coated to prevent adverse reactions involving the container material (inner wall) under high temperature conditions. This material replaces La with rare earth Sm and is doped with fluoride ion at the oxygen level. It is a new type of iron-arsenic series high-temperature superconducting material with the highest superconducting critical temperature in addition to the high-temperature superconducting copper oxide series. The superconducting critical temperature T _{c is} significantly increased from 28K to 53K after replacing La by Sm. Sm(0,F)FeAs is the material with the highest superconducting critical temperature in the current iron-arsenic series of high-temperature superconducting materials, and its superconducting critical temperature is 53K, which has broken the BCS theory predicts that the conventional superconductor superconducting critical temperature T _c cannot exceed the theoretical value of 40K, and it is also larger than the non-copper oxide superconductor MgB ₂ with the highest superconducting critical temperature T _C =39K. At the same time, the advantage of this material is that it has a high critical temperature and a high critical magnetic field, and it will have a broader application prospect than materials such as MgB ₂ . This will also help to further understand the physical mechanism of copper oxide high-temperature conductors and some basic physics in strong correlation systems, providing theoretical workers with challenges and practical topics. DRAWINGS

图 1是实施例 1所制得的 SmO,— _xF_xFeAs材料的 Meissner效应。 Figure 1 is the Meissner effect of the SmO, - _x F _x FeAs material prepared in Example 1.

图 2是实施例 1所制得的 SmO^FxFeAs材料的电阻率曲线。 Figure 2 is a graph showing the resistivity of the SmO^FxFeAs material obtained in Example 1.

图 3是实施例 2所制得的

材料的电阻率曲线。具体实施方式 Figure 3 is a preparation of Example 2

The resistivity curve of the material. detailed description

实施例 1 Example 1

1、前驱物 SmAs的制备 1. Preparation of precursors SmAs

在隔绝空气的高纯氩 (99.999%)气氛下，并且 H₂0含量小于 lppm，把 Sni 粉（99.99% )和 As粉（99.99% )充分研磨均匀，并压制成片，然后放入石英管中，将其抽至真空度小于 l(T³Pa, 密封后将石英管放入马伏炉中。以每分钟 2〜6摄氏度速率升温至 500~650度保温 3〜10小时，然后再以每分钟 2〜6摄氏度速率升温至 800-950度保温 5〜10小时，最后随炉冷却至室温，将反应物从石英管中取出后即完成前驱物制备过程。 In a high purity argon (99.999%) atmosphere isolated from air, and the H ₂ 0 content is less than 1 ppm, the Sni powder (99.99%) and the As powder (99.99%) are thoroughly ground and pressed into a sheet, and then placed in a quartz tube. In the middle, draw it to a degree of vacuum less than l (T ³ Pa, put the quartz tube into the muffle furnace after sealing. Warm up to 500~650 degrees at 3 to 6 degrees Celsius per minute for 3 to 10 hours, then The temperature is raised from 2 to 6 degrees Celsius per minute to 800-950 degrees for 5 to 10 hours. Finally, the furnace is cooled to room temperature, and the precursor is prepared by removing the reactants from the quartz tube.

2、目标物 SmO^FJFeAs的制备 2. Preparation of target SmO^FJFeAs

在隔绝空气的高纯氩 (99.999%)气氛下，并且 H₂0含量小于 lppm,将制备好的前驱物 SmAs粉末、 SmF₃粉末（ 99.99% )、？6粉末（ 98% )、Fe₂0₃粉末（ 99% ), As粉末 ( 99.99% )按照化学计量 SmAs： SmF₃： Fe： Fe₂0₃ :As= (l-x)/3： x/3： (l+2x)/3： (l-x)/3： x/3 , 其中， X=0.15，混合研磨均匀，并压制成片，再用 Ta 膜片包裹好放入石英管中抽真空至真空度小于 10—³Pa, 密封后将石英管放入高温管式炉中。以每分钟 2-6摄氏度速率升温至 1000 ~ 1200度保温 40 ~ 60小时，再以 2〜6。C/min降至室温，将反应物从石英管中取出后即完成最终化合物的制备过程。 In a high purity argon (99.999%) atmosphere isolated from air, and the H ₂ 0 content is less than 1 ppm, the prepared precursor SmAs powder, SmF ₃ powder (99.99%), ? 6 powder (98%), Fe ₂ 0 ₃ powder (99%), As powder (99.99%) according to stoichiometric SmAs: SmF ₃ : Fe: Fe ₂ 0 ₃ : As = (lx) / 3: x/3: (l+2x)/3: (lx)/3: x/3 , where X=0.15, mixed and ground evenly, and pressed into tablets, then wrapped in a Ta film and placed in a quartz tube to evacuate to a vacuum Less than 10 - ³ Pa, after sealing, put the quartz tube into a high temperature tube furnace. The temperature is raised at a rate of 2-6 degrees Celsius per minute to 1000 to 1200 degrees for 40 to 60 hours, and then 2 to 6. The C/min was lowered to room temperature, and the preparation of the final compound was completed after the reactant was taken out from the quartz tube.

图 1是实施例 1所制得的 Sm0_1-xF_xFeAs材料的 Meissner效应。图中 , ZFC 为零场冷却后再加磁场升温测量磁化率， FC为加磁场降温测量磁化率。这些数据能够估算出样品的超导体积含量。如图 1所示，在超导临界温度 T_c以下，超导材料体现一个 Meissner 态，即磁化率体现为负值，这磁化率开始转变的温度 T_C=43K是跟 2图电阻转变的中点是一致的。 1 is a Meissner effect of the Sm0 _1-x F _x FeAs material obtained in Example 1. In the figure, the ZFC is cooled to zero field and then the magnetic field is raised to measure the magnetic susceptibility. The FC is the magnetic field to measure the magnetic susceptibility. These data can estimate the superconducting volume content of the sample. As shown in Fig. 1, below the superconducting critical temperature T _c , the superconducting material exhibits a Meissner state, that is, the magnetic susceptibility is negative, and the temperature at which the magnetic susceptibility begins to transform T _C =43K is in the middle of the resistance transition of the 2 graph. The points are consistent.

图 2是实施例 1所制得的 SmO^FJFeAs材料的电阻率曲线。同时测量不同磁场（0T: 0特斯拉， 5Τ: 5特斯拉， 7Τ: 7特斯拉）下的电阻。由图 2可以看出，电阻开始明显下降的温度为 44Κ, 在将近 40Κ时电阻已经降到零。同时测量了不同磁场下的电阻，发现 7特斯拉对这个材料的超导临界温度没有明显的影响，这说这种材料的临界磁场非常的大。实施例 2 Figure 2 is a graph showing the resistivity of the SmO^FJFeAs material obtained in Example 1. Also measure the resistance under different magnetic fields (0T: 0 Tesla, 5Τ: 5 Tesla, 7Τ: 7 Tesla). It can be seen from Figure 2 that the temperature at which the resistance begins to drop significantly is 44 Κ, and the resistance has dropped to zero at nearly 40 。. At the same time, the resistance under different magnetic fields was measured, and it was found that 7 Tesla had no obvious influence on the superconducting critical temperature of this material, which means that the critical magnetic field of this material is very large. Example 2

除了 χ=0.2~0.3以外，以与实施例 1相同的方式制备目标化合物。 The target compound was prepared in the same manner as in Example 1 except that χ = 0.2 to 0.3.

图 3是实施例 2所制得的 SmO^F eAs材料的电阻率曲线。如图 3所示，电阻开始明显下降的温度为 53K, 在将近 48K时电阻已经降到零。 Figure 3 is a graph showing the resistivity of the SmO^F eAs material obtained in Example 2. As shown in Figure 3, the temperature at which the resistance begins to drop significantly is 53K, and the resistance has dropped to zero at nearly 48K.

Claims

权利要求书 Claim

1. 一种高温超导材料，其特征在于：其为以化学式

A high temperature superconducting material characterized in that it is in a chemical formula

所示的化合物，式中 X取自 0〜0.4。 The compound shown, wherein X is from 0 to 0.4.

2. 根据权利要求 1 所述的高温超导材料，其特征在于：式中 X 取自 0. 15〜0.3。 The high-temperature superconducting material according to claim 1, wherein X is taken from 0.15 to 0.3.

3. 根据权利要求 1或 2所述的高温超导材料，其特征在于：其临界超导温度为 0〜53K。 The high temperature superconducting material according to claim 1 or 2, wherein the critical superconducting temperature is 0 to 53K.

4. 一种制备权利要求 1或 2所述的高温超导材料的方法，先制备前驱物，再制备目标物，包括混合、焙烧和冷却，其特征在于：所述的前驱物为 SmAs，所述的目标物的制备是将 SmAs粉、纯度 99.99% 的 SmF₃粉、纯度 98%的 Fe粉、纯度 99%的 Fe₂0₃粉和纯度 99.99% 的 As粉按 SmAs ： SmF₃： Fe ： Fe₂0₃： As=(l -x)/3 ： x/3 ： ( l+2x)/3 ： ( l -x)/3 :x/3的摩尔比在无氧和水分含量≤lppm的气氛中研磨混合均匀并压制成片，包覆 Ta膜片，然后在真空度≤l (T³Pa 的条件下升温至 1000〜1200°C焙烧 40~60小时，再降至室温。 A method for producing the high-temperature superconducting material according to claim 1 or 2, wherein a precursor is prepared, and then a target is prepared, comprising mixing, calcining, and cooling, wherein: the precursor is SmAs, preparation of the desired compound described later is SMAS powder, purity of 99.99% SmF ₃ powder, 98% pure Fe powder, 99% pure Fe ₂ 0 ₃ powder and a purity of 99.99% As powder by SmAs: SmF _3: Fe: Fe ₂ 0 ₃ : As=(l -x)/3 : x/3 : ( l+2x)/3 : ( l -x)/3 :x/3 molar ratio in the absence of oxygen and moisture content ≤ lppm In the atmosphere, the mixture is uniformly mixed and pressed into a sheet, and the Ta film is coated, and then heated to 1000 to 1200 ° C under vacuum of ≤ 1 (T ³ Pa for 40 to 60 hours, and then lowered to room temperature.

5. 根据权利要求 4所述的方法，其特征在于：所述前驱物的制备为，取纯度为 99.99%的 Sm粉和 As粉在无氧和水分含量≤l ppm的气氛中研磨混合均匀并压制成片，然后在真空度≤l (T³Pa 的条件下升温至 500〜650 °C焙烧 3~10小时，再继续升温至 800~950°C焙烧 5~10 小时后冷却。 5. The method according to claim 4, wherein: the precursor is prepared by grinding and mixing the Sm powder and the As powder having a purity of 99.99% in an atmosphere having an oxygen-free and moisture content of ≤1 ppm and The sheet is pressed into a sheet, and then calcined at a vacuum degree of ≤ l (T ³ Pa to 500 to 650 ° C for 3 to 10 hours, and then further heated to 800 to 950 ° C for 5 to 10 hours and then cooled.

6. 根据权利要求 4或 5所述的方法，其特征在于：所述的升温和降温的速率为 l〜8 °C/min。 ' 6. Method according to claim 4 or 5, characterized in that the rate of temperature rise and temperature drop is l~8 °C/min. '

7. 根据权利要求 4或 5所述的方法,其特征在于：所述升温和降温的速率为 2〜6°C/niin。 The method according to claim 4 or 5, wherein the rate of temperature rise and fall is 2 to 6 ° C / niin.

S S