CN107437579A - The Fast Sintering preparation method of the superconducting thin films of Tl 2212 - Google Patents

Abstract

The invention discloses a rapid sintering preparation method of Tl-2212 superconducting thin film. Silver foil or gold foil is used to seal and wrap the amorphous precursor film containing thallium and the burning target containing thallium, and the Sintering in the environment. The invention includes four processes including the preparation of a precursor film, the preparation of a thallium source accompanying firing target, the rapid temperature-raising sintering of the precursor film in an argon/oxygen environment, and the oxygen-supplementing heat treatment of a primary sample. Compared with the traditional sintering method, the sintering conditions for growing Tl‑2212 thin films using this technology are not affected by the deposition method of the precursor film, the powder particle size of the starting material of the thallium source accompanying firing target and its preparation method, avoiding the Due to the replacement of the manufacturer's raw materials and the pioneering film deposition method, it is necessary to re-explore the sintering process for a long time. At the same time, the method also greatly reduces the amount of the thallium source accompanying the burning target, shortens the heating and cooling time and constant temperature time, reduces the production cost, and improves the repeatability of the experiment.

Description

Preparation method of Tl-2212 superconducting thin film by rapid sintering

technical field

The invention relates to the field of thallium superconducting thin film materials. More specifically, the present invention relates to a rapid sintering preparation method of Tl-2212 superconducting thin film.

Background technique

Tl ₂ Ba ₂ CaCu ₂ O ₈ (Tl-2212) superconducting thin film has the advantages of high critical temperature (T _c can reach 110K), high critical current density, and strong moisture resistance. An important material for high-performance high-temperature superconducting electronic devices.

In the current research on the synthesis of Tl-2212 thin films, the main methods for preparing precursor films include magnetron sputtering, pulsed laser deposition, Aerosol, MOCVD, Sol-gel, etc. The sintering processes of these studies have the following common points: (1) It is necessary to provide a thallium source to accompany the firing target to be sintered together with the precursor film; (2) The heating rate of the sintering equipment is low, usually 1-10°C/min, that is, 0.017-0.16°C/s. Using this sintering method, through exploration and research, high-quality Tl-2212 films can be prepared. However, this sintering process is greatly affected by the deposition method of the precursor film, the powder particle size of the starting material of the thallium source and firing target, and its preparation method. Changing the manufacturer of raw materials and the deposition method of the precursor film requires a lot of time to re-explore its preparation process. The reasons are: (1) The preparation method of the precursor film is different, the manufacturer of the raw material is different, and the size of the amorphous particles of the precursor film and the burning target is also different, so the volatilization temperature of Tl ₂ O ₃ is very different; (2) In order to prepare high-quality Tl-2212 films, a dynamic balance must be formed between the Tl volatilization of the precursor film and the Tl supplement provided by the burner target during the high-temperature sintering process; (3) the difference in volatilization temperature caused a huge change in the sintering process, which It takes a long time to explore.

Contents of the invention

It is an object of the present invention to solve at least the above-mentioned problems and to provide at least the advantages which will be described later.

Another object of the present invention is to provide a method for preparing T1-2212 superconducting film by rapid sintering. The prepared pure phase T1-2212 film has good superconducting properties, and the method has short heating and cooling time and constant temperature time. , low production cost, and the sintering process is not affected by the deposition method of the precursor film and the powder particle size of the starting material of the thallium source and firing target.

In order to achieve these objects and other advantages according to the present invention, a rapid sintering preparation method of Tl-2212 superconducting thin film is provided, using silver foil or gold foil to seal the amorphous precursor film containing thallium with the burnt target containing thallium Wrapped and sintered in a sealed argon or flowing oxygen environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 0.5-5°C/s; in the temperature range of 350-650°C, the heating rate is 1-10°C/s; in the temperature range of 650-780°C, the heating rate is 10 ~40°C/s, keep the sintering temperature at 730-780°C for 10-60 minutes, and cool down to room temperature under the action of cooling circulating water; or

In the oxygen flow environment: in the temperature zone of 0-350℃, the heating rate is 0.5-5℃/s; in the temperature zone of 350-650℃, the heating rate is 1-10℃/s; in the temperature zone of 650-860℃, the heating rate is 10 ~40°C/s, keep the sintering temperature at 810-860°C for 10-30 minutes, and cool down to room temperature under the action of cooling circulating water, that is to say;

Wherein, the metal ion molar ratio of Tl, Ba, Ca, and Cu in the amorphous precursor film containing thallium is 2.5-3.5:2:1:2.2-2.6;

The thallium-containing burner target is made by sintering the oxides of Ba, Ca and Cu with the molar ratio of metal ions Tl:Ba:Ca:Cu=1～2.6:2:2:3 and Tl ₂ O ₃ .

Preferably, in the method for preparing the Tl-2212 superconducting thin film by rapid sintering, after sintering the thallium-containing amorphous precursor film and the thallium-containing sintering target in an argon environment, oxygen supplement heat treatment is also included: The sample prepared by sintering in the environment is cooled and then transferred to the flowing oxygen environment, and the temperature is raised to 350°C at a speed of 1-5°C/s, and then heated to 400-710°C at a speed of 1-40°C/s. The temperature zone is kept at a constant temperature for 20-60min. Let cool and serve.

Preferably, in the preparation method of rapid sintering of the Tl-2212 superconducting thin film, the preparation method of the thallium-containing burner target is as follows: the metal ion molar ratio is Ba:Ca:Cu=2:2:3 Ba, The oxides of Ca and Cu are mixed and ground as the starting materials, kept at a constant temperature of 890-940°C for 4-8 hours in a flowing oxygen environment, crushed and then ground after cooling, kept at a constant temperature of 890-940°C for 4-8 hours in a flowing oxygen environment, and added Tl ₂ O ₃ is mixed and ground into tablets, so that the molar ratio of Tl and Ba is Tl:Ba=1~2.6:2, keep the temperature at 840~860°C for 1~2h in the flow oxygen environment, crush and grind after cooling, In an oxygen environment, keep the temperature at 840-860°C for 3-4 hours to obtain the burning target.

Preferably, in the preparation method of rapid sintering of the Tl-2212 superconducting thin film, the preparation method of the amorphous precursor film containing thallium adopts ion sputtering deposition method, pulsed laser deposition method, metal organic deposition method or sol-gel glue method.

Preferably, the rapid sintering preparation method of the Tl-2212 superconducting thin film, the preparation method of the amorphous precursor film containing thallium adopts the ion sputtering deposition method:

S1. Mix and grind BaO ₂ or BaO, CaO or CaCO ₃ and CuO with the molar ratio of metal ions Ba:Ca:Cu=2.3～2.6:1:2.1～2.4 as the starting material, in the flow oxygen environment 890～940 Keep the temperature at ℃ for 4-8 hours, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl and Ca is Tl:Ca=2.2-3:1, keep the temperature at 840-860 ℃ for 3-6 hours in the oxygen flow environment, After cooling, the sputtering target is obtained;

S2. Use radio frequency magnetron sputtering for the sputtering target, the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas, the sputtering pressure is 2.2-6Pa, and the sputtering power is 30-60W.

Preferably, in the rapid sintering preparation method of the Tl-2212 superconducting thin film, the substrate is lanthanum aluminate, sapphire, magnesium oxide, yttrium-stabilized zirconia or textured metal substrate material alloy.

Preferably, in the rapid sintering preparation method of the Tl-2212 superconducting thin film, when sintering in an argon or oxygen flow environment, the argon or oxygen pressure is 1 atm.

Preferably, in the method for preparing the Tl-2212 superconducting thin film by rapid sintering, the thickness of the prepared Tl-2212 superconducting thin film is 10nm-2.5μm.

The present invention at least includes the following beneficial effects:

First, the present invention adopts a three-stage heating process, which avoids the generation of film cracks and overcomes the problem that the traditional low-speed heating sintering process is affected by the deposition method of the precursor film and the powder particle size of the starting material of the thallium source accompanying firing target , the prepared Tl-2212 superconducting film has a smooth surface and good superconductivity;

Second, the present invention greatly shortens the heating and cooling time and constant temperature time, and has the advantages of simple process, short preparation time of a single sample (about 4 hours including three stages of heating, cooling, and oxygen supplementation), less consumption of burning targets, and low production cost. inferior merit;

Third, the burner target of the present invention supplements the Tl element for the precursor film of the present invention, and the Tl content in the precursor film can vary in a wide range, and after sintering, a Tl-2212 film with good superconducting properties can be obtained; the burner target The content of Tl in the medium varies widely, and the yield of single sintering is high;

Fourth, the pure phase Tl-2212 superconducting thin film prepared by the present invention has higher crystallization quality, more complete grain growth, more orderly arrangement, better c-axis orientation of the thin film, smooth surface of the Tl-2212 superconducting thin film, And no cracks.

Other advantages, objectives and features of the present invention will partly be embodied through the following descriptions, and partly will be understood by those skilled in the art through the study and practice of the present invention.

Description of drawings

Fig. 1 is the V-T figure of the T1-2212 superconducting thin film of embodiment 3 before supplementary oxygen;

Fig. 2 is the XRD pattern of the T1-2212 superconducting thin film of embodiment 6 after supplementing oxygen;

Fig. 3 is the SEM scanning figure of the T1-2212 superconducting thin film of embodiment 6 after supplementing oxygen;

Fig. 4 is the V-T figure of the T1-2212 superconducting thin film of embodiment 6 after supplementing oxygen;

Fig. 5 is the XRD pattern of the T1-2212 superconducting thin film of embodiment 9 under flowing oxygen environment;

Fig. 6 is the V-T diagram of the Tl-2212 superconducting thin film of embodiment 9 under the flowing oxygen environment.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments, so that those skilled in the art can implement it with reference to the description.

It should be noted that the experimental methods described in the following embodiments, unless otherwise specified, are conventional methods, and the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

<Example 1>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is CeO ₂ / sapphire, comprising:

Step 1. Preparation of thallium-containing amorphous precursor film by sol-gel method: starting materials of thallium, barium, calcium, copper acetate, propionic acid, lactic acid, diethylenetriamine, methanol, etc. A complexing agent and a solvent are used to prepare a sol _; a gel film is prepared from the sol on a sapphire substrate with a CeO2 isolation layer, and a precursor film is obtained through drying and thermal decomposition processes. The Tl, Ba, Ca, and Cu of the prepared precursor film are The molar ratio of metal ions is 2.5:2:1:2.2;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 4 hours, after cooling, pulverize and then grind, and keep the temperature at 890~940℃ for 4 hours in the flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl and Ba is Tl:Ba=1:2, Keep the temperature at 840-860°C for 1 hour in a flowing oxygen environment, crush and grind after cooling, and keep the temperature at 840-860°C in a flowing oxygen environment for 3 hours to obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: use silver foil or gold foil to seal and wrap the precursor film and the accompanying firing target, put them into the closed quartz tube of the rapid heat treatment equipment, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 0.5°C/s; in the temperature range of 350-650°C, the heating rate is 1°C/s; in the temperature range of 650-780°C, the heating rate is 40°C/s. Keep the sintering temperature at 730-780°C for 10 minutes, and cool down to room temperature under the action of cooling circulating water to obtain primary samples;

Step 4. Oxygen supplement heat treatment: heat the sample prepared in step 3 to 350°C at a rate of 1°C/s in a flowing oxygen environment, and then raise the temperature to 400-710°C at a rate of 1°C/s for 20 minutes at a constant temperature in the cooling cycle. The effect of water drops to room temperature, and Tl-2212 pure phase film with _Tc of 104K is obtained.

<Example 2>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is CeO ₂ / sapphire, comprising:

Step 1. Preparation of thallium-containing amorphous precursor film by sol-gel method: starting materials of thallium, barium, calcium, copper acetate, propionic acid, lactic acid, diethylenetriamine, methanol, etc. A complexing agent and a solvent are used to prepare a sol _; a gel film is prepared from the sol on a sapphire substrate with a CeO2 isolation layer, and a precursor film is obtained through drying and thermal decomposition processes. The Tl, Ba, Ca, and Cu of the prepared precursor film are The molar ratio of metal ions is 3.5:2:1:2.6;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 8 hours, after cooling, pulverize and grind again, keep the temperature at 890-940℃ for 8 hours in the flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl and Ba is Tl:Ba=2.6:2, Keep the temperature at 840-860°C for 2 hours in a flowing oxygen environment, crush and grind after cooling, and keep the temperature at 840-860°C for 4 hours in a flowing oxygen environment to obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: use silver foil or gold foil to seal and wrap the precursor film and the accompanying firing target, put them into the closed quartz tube of the rapid heat treatment equipment, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 5°C/s; in the temperature range of 350-650°C, the heating rate is 10°C/s; in the temperature range of 650-780°C, the heating rate is 10°C/s. Keep the sintering temperature at 730-780°C for 60 minutes, and cool down to room temperature under the action of cooling circulating water to obtain primary samples;

Step 4. Oxygen supplement heat treatment: heat the sample prepared in step 3 to 350°C at a rate of 5°C/s in a flowing oxygen environment, and then raise the temperature to 400-710°C at a rate of 40°C/s for 60 minutes at a constant temperature in the cooling cycle. The effect of water drops to room temperature, and Tl-2212 pure phase film with _Tc of 104K is obtained.

<Example 3>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1, preparing an amorphous precursor film containing thallium: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.4:1:2.2 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 6 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl and Ca is Tl:Ca=2.6:1, put them into a sealed crucible, and place them together in a sealed In the quartz tube, keep the constant temperature at 840-860°C for 4.5 hours in a flowing oxygen environment, and obtain the sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/ _O2 mixed gas, the sputtering pressure is 2.2-6Pa, and the sputtering power is 45W; the molar ratio of Tl, Ba, Ca, and Cu metal ions in the prepared precursor film is 3:2:1:2.4;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 6h, after cooling, pulverize and then grind, repeat sintering once, add Tl ₂ O ₃ to mix and grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=1.8:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 1.5h in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C for 3.5h in the flowing oxygen environment, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: seal and wrap the precursor film and the accompanying firing target, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 2.5°C/s; in the temperature range of 350-650°C, the heating rate is 5°C/s; in the temperature range of 650-780°C, the heating rate is 25°C/s. Keep the sintering temperature at 730-780°C for 35 minutes, cool down to room temperature under the action of cooling circulating water, and obtain a Tl-2212 pure-phase film with a _Tc of 100K, as shown in Figure 1.

It can be seen from Figure 1 that the critical transition temperature of the superconducting thin film without oxygen supplement heat treatment is only 100K. This is due to sintering under high temperature argon, which causes oxygen deficiency in the film, and oxygen supplement treatment is required to increase its critical transition temperature. .

<Example 4>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1, preparing an amorphous precursor film containing thallium: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.3:1:2.1 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 4 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl to Ca is Tl:Ca=2.2:1, put them into a sealed crucible, and place them together in a sealed In a quartz tube, keep the constant temperature at 840-860°C for 3 hours in a flowing oxygen environment, and obtain a sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas , the sputtering pressure is 2.2～6Pa, the sputtering power is 30W; the metal ion molar ratio of Tl, Ba, Ca and Cu of the prepared precursor film is 2.5:2:1:2.2;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 4 hours, crush and grind after cooling, repeat sintering once, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=1:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 1 hour in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C in the flowing oxygen environment for 3 hours, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: seal and wrap the precursor film and the accompanying firing target, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 0.5°C/s; in the temperature range of 350-650°C, the heating rate is 1°C/s; in the temperature range of 650-780°C, the heating rate is 40°C/s. Keep the sintering temperature at 730-780°C for 10 minutes, and cool down to room temperature under the action of cooling circulating water;

Step 4. Oxygen supplement heat treatment: heat the sample prepared in step 3 to 350°C at a rate of 1°C/s in a flowing oxygen environment, and then raise the temperature to 400-710°C at a rate of 1°C/s for 20 minutes at a constant temperature in the cooling cycle. The effect of water dropped to room temperature, and Tl-2212 pure phase film with _Tc of 106.8K was obtained.

<Example 5>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1. Preparation of thallium-containing amorphous precursor film: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.6:1:2.4 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 8 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl and Ca is Tl:Ca=3:1, put them into a sealed crucible, and put them together in a sealed In a quartz tube, keep the constant temperature at 840-860°C for 6 hours in a flowing oxygen environment, and obtain a sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas , the sputtering pressure is 2.2～6Pa, the sputtering power is 60W; the metal ion molar ratio of Tl, Ba, Ca and Cu of the prepared precursor film is 3.5:2:1:2.6;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Constant temperature at ℃ for 8h, after cooling, pulverize and then grind, repeat sintering once, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=2.6:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 2 hours in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C in the flowing oxygen environment for 4 hours, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: seal and wrap the precursor film and the accompanying firing target, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 5°C/s; in the temperature range of 350-650°C, the heating rate is 10°C/s; in the temperature range of 650-780°C, the heating rate is 10°C/s. Keep the sintering temperature at 730-780°C for 60 minutes, and cool down to room temperature under the action of cooling circulating water;

Step 4. Oxygen supplement heat treatment: heat the sample prepared in step 3 to 350°C at a rate of 5°C/s in a flowing oxygen environment, and then raise the temperature to 400-710°C at a rate of 40°C/s for 60 minutes at a constant temperature in the cooling cycle. The effect of water dropped to room temperature, and Tl-2212 pure phase film with _Tc of 106.8K was obtained.

<Example 6>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1, preparing an amorphous precursor film containing thallium: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.4:1:2.2 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 6 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl and Ca is Tl:Ca=2.6:1, put them into a sealed crucible, and place them together in a sealed In the quartz tube, keep the constant temperature at 840-860°C for 4.5 hours in a flowing oxygen environment, and obtain the sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/ _O2 mixed gas, the sputtering pressure is 2.2-6Pa, and the sputtering power is 45W; the molar ratio of Tl, Ba, Ca, and Cu metal ions in the prepared precursor film is 3:2:1:2.4;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 6h, after cooling, pulverize and then grind, repeat sintering once, add Tl ₂ O ₃ to mix and grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=1.8:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 1.5h in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C for 3.5h in the flowing oxygen environment, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: seal and wrap the precursor film and the accompanying firing target, and sinter in a sealed argon environment:

In argon environment: in the temperature range of 0-350°C, the heating rate is 2.5°C/s; in the temperature range of 350-650°C, the heating rate is 5°C/s; in the temperature range of 650-780°C, the heating rate is 25°C/s. Keep the sintering temperature at 730-780°C for 35 minutes, and cool down to room temperature under the action of cooling circulating water;

Step 4. Oxygen supplement heat treatment: heat the sample prepared in step 3 to 350°C at a rate of 3°C/s in a flowing oxygen environment, and then raise the temperature to 400-710°C at a rate of 20°C/s for 40 minutes at a constant temperature in the cooling cycle. The effect of water drops to room temperature, and the Tl-2212 pure phase film with _Tc of 106.8K is obtained, as shown in Figures 2, 3, and 4. It can be seen from Figure 2 that except for the (00l) diffraction peak and the substrate peak of the Tl-2212 superconducting phase, the film has no grains of other orientations, and the film grows in the c-axis orientation; it can be seen from Figure 3 that there are layers on the surface of the film Shaped growth structure without cracks, some small particles and a small number of small holes on the surface, these small holes do not extend to the bottom, and have little effect on the superconducting properties of the film; Figure 4 shows that the superconducting transition temperature of the film is 106.8K .

<Example 7>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1, preparing an amorphous precursor film containing thallium: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.3:1:2.1 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 4 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl to Ca is Tl:Ca=2.2:1, put them into a sealed crucible, and place them together in a sealed In a quartz tube, keep the constant temperature at 840-860°C for 3 hours in a flowing oxygen environment, and obtain a sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas , the sputtering pressure is 2.2～6Pa, the sputtering power is 30W; the metal ion molar ratio of Tl, Ba, Ca and Cu of the prepared precursor film is 2.5:2:1:2.2;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 4 hours, crush and grind after cooling, repeat sintering once, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=1:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 1 hour in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C in the flowing oxygen environment for 3 hours, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: use silver foil or gold foil to seal and wrap the precursor film and the accompanying firing target, put them into the closed quartz tube of the rapid heat treatment equipment, and sinter in the flowing oxygen environment:

In the oxygen flow environment: the oxygen pressure is 1 atm, the temperature rise rate is 0.5°C/s in the temperature range of 0-350°C, the temperature rise rate is 1°C/s in the temperature range of 350-650°C, and the temperature rise rate is 1°C/s in the temperature range of 650-860°C. 40°C/s, keep the sintering temperature at 810-860°C for 10 minutes, and cool down to room temperature under the action of cooling circulating water to obtain a Tl-2212 pure phase film with a _Tc of 104K.

<Embodiment 8>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1. Preparation of thallium-containing amorphous precursor film: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.6:1:2.4 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 8 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl and Ca is Tl:Ca=3:1, put them into a sealed crucible, and put them together in a sealed In a quartz tube, keep the constant temperature at 840-860°C for 6 hours in a flowing oxygen environment, and obtain a sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas , the sputtering pressure is 2.2～6Pa, the sputtering power is 60W; the metal ion molar ratio of Tl, Ba, Ca and Cu of the prepared precursor film is 3.5:2:1:2.6;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Constant temperature at ℃ for 8h, after cooling, pulverize and then grind, repeat sintering once, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=2.6:2, seal it with a crucible and place it in a sealed quartz In the tube, keep the constant temperature at 840-860°C for 2 hours in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C in the flowing oxygen environment for 4 hours, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: use silver foil or gold foil to seal and wrap the precursor film and the accompanying firing target, put them into the closed quartz tube of the rapid heat treatment equipment, and sinter in the flowing oxygen environment:

In the oxygen flow environment: the oxygen pressure is 1atm, in the temperature range of 0-350°C, the heating rate is 5°C/s; in the temperature range of 350-650°C, the heating rate is 10°C/s; 10°C/s, keep the sintering temperature at 810-860°C for 30 minutes, and cool down to room temperature under the action of cooling circulating water to obtain a Tl-2212 pure phase film with a _Tc of 104K.

<Example 9>

A kind of rapid sintering preparation method of Tl-2212 superconducting film, substrate is lanthanum aluminate, comprising:

Step 1, preparing an amorphous precursor film containing thallium: BaO ₂ or BaO, CaO or CaCO ₃ and CuO with a metal ion molar ratio of Ba:Ca:Cu=2.4:1:2.2 are mixed and ground as starting materials, and the Keep the temperature at 890-940°C for 6 hours in a flowing oxygen environment, add Tl ₂ O ₃ to mix, grind and press tablets, so that the molar ratio of Tl and Ca is Tl:Ca=2.6:1, put them into a sealed crucible, and place them together in a sealed In the quartz tube, keep the constant temperature at 840-860°C for 4.5 hours in a flowing oxygen environment, and obtain the sputtering target after cooling; use radio frequency magnetron sputtering for the sputtering target, and the sputtering gas is high-purity Ar or Ar/ _O2 mixed gas, the sputtering pressure is 2.2-6Pa, and the sputtering power is 45W; the molar ratio of Tl, Ba, Ca, and Cu metal ions in the prepared precursor film is 3:2:1:2.4;

Step 2. Preparation of thallium-containing burner target: Mix and grind BaO ₂ , CaO and CuO with a metal ion molar ratio of Ba:Ca:Cu=2:2:3 as starting materials. Keep the temperature at ℃ for 4-8 hours, cool down, pulverize and then grind, repeat sintering once, add Tl ₂ O ₃ to mix and grind and press into tablets, so that the molar ratio of Tl to Ba is Tl:Ba=1.8:2, seal with a crucible and place in a sealed In the quartz tube, keep the constant temperature at 840-860°C for 1.5h in the flowing oxygen environment, crush and grind after cooling, keep the constant temperature at 840-860°C for 3.5h in the flowing oxygen environment, and obtain the burning target;

Step 3. Rapid sintering of the precursor film and the accompanying firing target: use silver foil or gold foil to seal and wrap the precursor film and the accompanying firing target, put them into the closed quartz tube of the rapid heat treatment equipment, and sinter in the flowing oxygen environment:

In the oxygen flow environment: the oxygen pressure is 1 atm, the temperature rise rate is 2.5°C/s in the temperature range of 0-350°C, the temperature rise rate is 5°C/s in the temperature range of 350-650°C, and the temperature rise rate is 5°C/s in the temperature range of 650-860°C. 25°C/s, keep the sintering temperature at 810-860°C for 20 minutes, cool down to room temperature under the action of cooling circulating water, and obtain a Tl-2212 pure phase film with a _Tc of 104K, as shown in Figure 5 and Figure 6.

<Comparative example 1>

The same as in Example 6, the difference is that the three-stage heating process is not used, and the sintering process of steps 3 and 4 is changed to a one-stage heating process, that is, the temperature is directly raised to 780 °C at a rate greater than 25 °C/s at room temperature, and then Constant temperature 10 ~ 60min. The superconducting film prepared by this method has obvious cracks on the surface, which affects the superconducting performance of the film.

<Comparative example 2>

Same as Example 6, the difference is that the three-stage heating process is not adopted, and the sintering process of steps 3 and 4 is changed to a traditional one-stage low-speed heating sintering process: that is, the temperature is directly raised to 730～780℃, then keep the temperature for 10～60min.

Cracks appeared in the superconducting thin film prepared in Comparative Example 1, indicating that in a heating process, if the heating rate is too fast (greater than 25°C/s), the stress on the micro-regions in the thin film will be uneven, resulting in cracking of the thin film and seriously reducing the thickness of the thin film. superconducting properties.

Comparative example 2, a Tl-2212 superconducting thin film was prepared by a traditional one-stage low-speed heating sintering process. This sintering process is affected by the deposition method of the precursor film, the powder particle size of the starting material of the thallium source accompanying firing target, and its preparation method. great influence. Changing the manufacturer of raw materials and the deposition method of the precursor film requires a lot of time to re-explore its preparation process. The reasons are: (1) The preparation method of the precursor film is different, the manufacturer of the raw material is different, and the size of the amorphous particles of the precursor film and the burning target is also different, so the volatilization temperature of Tl ₂ O ₃ is very different; (2) In order to prepare high-quality Tl-2212 films, a dynamic balance must be formed between the Tl volatilization of the precursor film and the Tl supplement provided by the burner target during the high-temperature sintering process; (3) the difference in volatilization temperature caused a huge change in the sintering process, This requires a longer exploration. For example, if the powder particles of the prepared burner target are larger than the particles of the precursor film, the volatilization temperature of Tl ₂ O ₃ in the burner target is higher than that of the precursor film, so that the precursor film will be partially volatilized before the temperature is raised to a constant temperature at a low speed. Or completely volatilized, the film obtained in this way is a mixed phase film, and its critical temperature is very low or not superconducting.

Compared with the traditional sintering process, the preparation time of a single sample in Example 6 is about 4 hours, and the preparation time of a single sample in the traditional sintering process is about 20 hours. Example 6 shortens the preparation time and reduces the power consumption.

<Comparative example 3>

The same as Example 6, the difference is that the preparation process of the traditional burning target in step 2 is generally: the component ratios of the burning target used are respectively Tl:Ba:Ca:Cu=2～2.5:2:2:3 .

Obviously, the single burning target Tl content variation range of embodiment 6 is larger, has increased yield; Its usage can be reduced by half, has reduced preparation cost (the cost of burning target is mainly determined by Tl content). At the same time, due to the rapid heating sintering and complete sealing of the sample in Example 6, the effective use times of a single burner target is 5-6 times that of the traditional method. Combining these two aspects will reduce the material cost by more than 10 times.

The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations to the present invention will be apparent to those skilled in the art.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and embodiments shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (8)

1. A rapid sintering preparation method of Tl-2212 superconducting thin film is characterized in that, use silver foil or gold foil to contain thallium-containing amorphous precursor film and contain thallium-containing burning target sealing wrap, and in sealing argon or Sintering in oxygen flow environment: In argon environment: in the temperature range of 0-350°C, the heating rate is 0.5-5°C/s; in the temperature range of 350-650°C, the heating rate is 1-10°C/s; in the temperature range of 650-780°C, the heating rate is 10 ~40°C/s, keep the sintering temperature at 730-780°C for 10-60 minutes, and cool down to room temperature under the action of cooling circulating water; or In the oxygen flow environment: in the temperature zone of 0-350℃, the heating rate is 0.5-5℃/s; in the temperature zone of 350-650℃, the heating rate is 1-10℃/s; in the temperature zone of 650-860℃, the heating rate is 10 ~40°C/s, keep the sintering temperature at 810-860°C for 10-30 minutes, and cool down to room temperature under the action of cooling circulating water, that is to say; Wherein, the metal ion molar ratio of Tl, Ba, Ca, and Cu in the amorphous precursor film containing thallium is 2.5-3.5:2:1:2.2-2.6; The thallium-containing burner target is made by sintering the oxides of Ba, Ca and Cu with the molar ratio of metal ions Tl:Ba:Ca:Cu=1～2.6:2:2:3 and Tl ₂ O ₃ . 2. the rapid sintering preparation method of Tl-2212 superconducting thin film as claimed in claim 1 is characterized in that, the amorphous precursor film containing thallium and the accompanying firing target containing thallium after sintering in an argon environment also include supplementary Oxygen heat treatment: Cool the sample prepared by sintering in an argon atmosphere, transfer it to a flow oxygen environment, raise the temperature to 350°C at a speed of 1-5°C/s, and then raise the temperature to a temperature of 400-710°C at a speed of 1-40°C/s Zone constant temperature 20 ~ 60min, cooling, that is. 3. the rapid sintering preparation method of T1-2212 superconducting thin film as claimed in claim 1 is characterized in that, the preparation method of the burnt target containing thallium is: the metal ion mol ratio is Ba:Ca:Cu=2: Mix and grind the oxides of Ba, Ca and Cu at 2:3 as the starting materials, keep the temperature at 890-940°C for 4-8 hours in a flowing oxygen environment, crush and grind after cooling, and then grind them in a flowing oxygen environment at 890-940°C Constant temperature for 4-8 hours, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl and Ba is Tl:Ba=1-2.6:2, keep the temperature at 840-860°C for 1-2 hours in an oxygen flow environment, after cooling Crush and then grind, and keep the temperature at 840-860°C for 3-4 hours in an oxygen flow environment to obtain the burner target. 4. the rapid sintering preparation method of Tl-2212 superconducting thin film as claimed in claim 1 is characterized in that, the preparation method of the amorphous precursor film that contains thallium adopts ion sputtering deposition method, pulsed laser deposition method, organometallic deposition method or sol-gel method. 5. the rapid sintering preparation method of T1-2212 superconducting thin film as claimed in claim 4 is characterized in that, the preparation method of the amorphous precursor film that contains thallium adopts ion sputtering deposition method: S1. Mix and grind BaO ₂ or BaO, CaO or CaCO ₃ and CuO with the molar ratio of metal ions Ba:Ca:Cu=2.3～2.6:1:2.1～2.4 as the starting material, in the flow oxygen environment 890～940 Keep the temperature at ℃ for 4-8 hours, add Tl ₂ O ₃ to mix, grind and press into tablets, so that the molar ratio of Tl and Ca is Tl:Ca=2.2-3:1, keep the temperature at 840-860 ℃ for 3-6 hours in the oxygen flow environment, After cooling, the sputtering target is obtained; S2. Use radio frequency magnetron sputtering for the sputtering target, the sputtering gas is high-purity Ar or Ar/O ₂ mixed gas, the sputtering pressure is 2.2-6Pa, and the sputtering power is 30-60W. 6. the rapid sintering preparation method of T1-2212 superconducting film as claimed in claim 1, is characterized in that, substrate is lanthanum aluminate, sapphire, magnesium oxide, yttrium stabilized zirconia or textured metal substrate material alloy. 7. The rapid sintering preparation method of T1-2212 superconducting thin film as claimed in claim 1, is characterized in that, when sintering in argon or flowing oxygen environment, argon or oxygen pressure is 1 atm. 8. The rapid sintering preparation method of Tl-2212 superconducting thin film as claimed in claim 1, characterized in that, the thickness of the prepared Tl-2212 superconducting thin film is 10nm～2.5μm.