Single-ion-doped lanthanum oxide block material capable of directionally regulating and controlling superconducting performance as well as preparation method and application of single-ion-doped lanthanum oxide block material

Abstract

The invention discloses a single-ion-doped lanthanum oxide block material capable of directionally regulating and controlling superconducting performance as well as a preparation method and application of the single-ion-doped lanthanum oxide block material. The preparation method comprises the following steps: S1, in an inert gas atmosphere, mixing and pressing lanthanum oxide, metal lanthanum and a doped ion source into a precast block; the doped ion source is selected from a yttrium source or a nitrogen source; s2, the prefabricated block is put into a multi-surface jacking machine, the pressure is increased to 4.5-5.5 GPa, and the pressure is maintained; then, the temperature is increased to 1473-1653 K at the speed of 100-200 K / min, heat preservation is conducted, and the single-ion-doped lanthanum oxide block material La < 1-x > Y < x > O or LaO < 1-y > Ny is prepared; wherein x is selected from the group consisting of 0.04 to 0.11; and y is selected from 0.40 to 0.70. The block material prepared by the method has a pure NaCl type crystal structure, the impurity phase content is less than or equal to 4%, the superconductive critical temperature is high, and the superconductor volume is close to 100%.

Description

Technical Field

[0001] This invention belongs to the technical field of rare earth functional materials, and more specifically, relates to a single-ion doped lanthanum oxide bulk material with directional control of superconducting properties, its preparation method, and its application. Background Technology

[0002] Rare earth monooxides (REOs), due to their unique NaCl-type crystal structure and 4f / 5d electronic configuration, possess multiple magnetoelectric properties, including superconductivity and magnetism, making them core candidate materials for superconducting electronics and magnetic storage. Among them, lanthanum oxide (LaO) is the most promising material in this system for research and application. As a typical rare earth monooxide superconducting material, it has significant application potential in the field of low-temperature superconductivity due to its NaCl-type crystal structure and superconducting properties.

[0003] However, the preparation and application of LaO in the existing technology have the following core defects: (1) Morphological limitations and lattice distortion problems: Most of the reported LaO is prepared by epitaxial growth in the form of thin films (such as growth on yttrium aluminum oxide (YAlO3) substrates); due to the significant lattice mismatch between the thin film and the substrate, the thin film has a structural distortion of c / a≠1, and the magnetoelectric properties are seriously deviated from the intrinsic values ​​(such as the superconducting critical temperature of LaO thin film is only 4.25-5.24K, which is lower than the intrinsic value of bulk materials), which cannot meet the requirements of actual devices for the intrinsic properties of materials. (2) Low purity of rare earth monooxide bulk preparation: the existing bulk preparation method (belt high pressure press) is difficult to suppress the generation of impurity phases, and impurities such as lanthanum oxide (La2O3) and rare earth metals are easily introduced into the product. The impurity phase content is generally higher than 5%, and the high impurity phase content makes it difficult for the bulk materials to be further applied in the industry. Therefore, how to further improve the purity and superconducting performance of rare earth monooxide bulk materials has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, the primary objective of this invention is to provide a method for preparing single-ion doped lanthanum oxide bulk materials.

[0005] A second objective of this invention is to provide a single-ion-doped lanthanum oxide bulk material prepared by the above-described preparation method.

[0006] A third objective of this invention is to provide the application of single-ion-doped bulk lanthanum oxide materials in superconducting devices.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] This invention claims protection for a method for preparing a single-ion-doped bulk lanthanum oxide material, characterized by comprising the following steps: S1. Lanthanum oxide, metallic lanthanum, and a doping ion source are mixed and pressed into a preform in an inert gas atmosphere; the doping ion source is selected from a yttrium source or a nitrogen source; S2. The preform is placed in a multi-faceted press, pressurized to 4.5-5.5 GPa, and held at that pressure; then heated to 1473-1653 K at a rate of 100-200 K / min and held at that temperature to prepare a single-ion doped lanthanum oxide bulk material La. 1-x Y x O or LaO 1-y N y ; Where x is selected from 0.04 to 0.11; y is selected from 0.40 to 0.70.

[0009] This invention utilizes a multi-faceted press to achieve precise high-temperature, high-pressure (HPHT) synthesis. A preform consisting of lanthanum oxide, metallic lanthanum, and a dopant ion source is heated to a specific temperature range within a defined pressure range using a specific heating rate, successfully preparing a single-ion-doped lanthanum oxide bulk material with a pure NaCl-type crystal structure. The specific high-pressure environment suppresses impurity phase formation; while the specific heating rate and high temperature range better promote atomic diffusion and complete reaction, allowing lanthanum oxide and metallic lanthanum to fully react and generate the target product. Furthermore, this method avoids bulk material cracking or lattice distortion caused by abrupt temperature / pressure changes. The inventors discovered that the molar ratio of the dopant ion sources in the system needs to be maintained within a suitable range. When the number of dopant ion sources is too high, the purity of the bulk material decreases significantly, making it difficult to meet subsequent processing requirements.

[0010] The single-ion-doped lanthanum oxide bulk material prepared by this invention has an impurity phase content of ≤4% and exhibits a pure NaCl-type crystal structure, achieving intrinsic structure control. The superconducting critical temperature of the single-ion-doped lanthanum oxide bulk material prepared by the above method of this invention is higher than that of existing thin film samples, and the superconducting volume is close to 100%, demonstrating superior superconducting performance. This invention employs a multi-faceted top-pressing machine for preparation, ensuring controllable process parameters and performance; it has advantages such as short preparation cycle, controllable raw material costs, and suitability for industrial-scale production.

[0011] Preferably, in step S1, the yttrium source is yttrium oxide; and / or the nitrogen source is selected from lanthanum nitride.

[0012] Preferably, in step S1, the mixing and pressing pressure is 5-8 MPa. More preferably, the mixing and pressing pressure is 5-6 MPa.

[0013] Preferably, in step S1, the purity of the lanthanum oxide is ≥99.99%; and / or the purity of the metallic lanthanum is ≥99.7%; and / or the purity of the doping ion source is ≥99.7%.

[0014] Preferably, in step S2, the pressure boosting rate is 0.3-1 GPa / min. More preferably, in step S2, the pressure boosting rate is 0.5-0.8 GPa / min.

[0015] Preferably, in step S2, the pressure holding time is 1-5 minutes. More preferably, in step S2, the pressure holding time is 2-4 minutes.

[0016] Preferably, in step S2, the heat preservation time is 2-4 hours.

[0017] Preferably, x is selected from 0.05-0.10; y is selected from 0.45-0.66. Specifically, x can be selected from 0.06, 0.07, 0.08, 0.09, etc., or any range formed by the above values, such as 0.05-0.07, 0.06-0.09, etc., and the present invention is not limited thereto. Specifically, y can be selected from 0.50, 0.55, 0.60, 0.65, etc., or any range formed by the above values, such as 0.45-0.50, 0.50-0.55, 0.50-0.60, etc., and the present invention is not limited thereto.

[0018] More preferably, y is selected from 0.45-0.55. Under these preferred conditions, the prepared single-ion doped bulk lanthanum oxide material LaO0 is... 1-y N y It has a higher superconducting critical temperature and superior superconducting properties.

[0019] Preferably, step S1 further includes a pretreatment step of the lanthanum oxide; the pretreatment operation is to anneal the lanthanum oxide at 1173-1273 K in an air atmosphere. Pretreatment removes adsorbed water and trace impurities from the surface of the lanthanum oxide raw material, thereby improving the purity of the final single-ion doped lanthanum oxide bulk material and reducing the content of impurity phases.

[0020] Preferably, in step S1, the molar ratio of lanthanum oxide to lanthanum metal is 1:1-1.05.

[0021] Furthermore, this invention claims protection for the single-ion-doped lanthanum oxide bulk material prepared by the above-described preparation method.

[0022] Furthermore, this invention seeks to protect the application of single-ion-doped lanthanum oxide bulk materials in superconducting devices.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing single-ion-doped lanthanum oxide bulk materials. Using a yttrium or nitrogen source as the doping ion source, and employing a multi-faceted press combined with specific preparation processes, the resulting bulk material exhibits a pure NaCl-type crystal structure, an impurity phase content ≤4%, a higher superconducting critical temperature, and a superconducting volume approaching 100%, demonstrating excellent superconducting properties. The preparation method provided by this invention has a short cycle time and can be mass-produced. Attached Figure Description

[0024] Figure 1 The images show the XRD patterns of the bulk materials prepared in Examples 1-4, Comparative Examples 1-3, and undoped LaO bulk materials.

[0025] Figure 2 The images show the magnetization and resistance measurements of the bulk materials prepared in Examples 1-2 and Comparative Example 1, and the undoped LaO bulk material. Figure 2 In the figure, 'a' represents the magnetization intensity test diagram of the above bulk material under an applied magnetic field of 20 Oe; Figure 2 In the figure, b is the magnetization intensity test diagram of the bulk material prepared in Example 1 under different external magnetic fields; Figure 2 In the figure, c represents the resistance change with temperature of the bulk materials prepared in Examples 1-2 and Comparative Example 1 and the undoped LaO bulk material; Figure 2 d in Figure 2 Enlarged view of the low-temperature region of c.

[0026] Figure 3 The magnetization intensity test diagrams are for the bulk materials prepared in Examples 3-4. Detailed Implementation

[0027] The present invention will be further described below with reference to the specification and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0028] Lanthanum oxide (La2O3) powder: purity 99.999%, McLean.

[0029] Yttrium oxide (Y2O3): purity 99.99%, Aladdin.

[0030] Lanthanum metal: 99.7% purity, 40 mesh, Alfa Esa.

[0031] Lanthanum nitride: 99.9% purity, Maclean's.

[0032] Example 1 La 0.9 Y 0.1 Preparation of O-block (1) Raw material pretreatment: La2O3 and Y2O3 were calcined at 1273 K in air atmosphere for 10 h to remove adsorbed water and trace impurities on the surface; after calcination, they were transferred to a glove box filled with argon; lanthanum and yttrium were directly placed in the glove box for later use.

[0033] (2) Mixing and pressing: Weigh 0.184 g La2O3, 0.096 g lanthanum (5% excess) and 0.022 g Y2O3 according to the ratio and put them into an agate mortar. Grind for 40 min until the particle size is ≤3μm to ensure that the raw materials are mixed evenly. Put the evenly mixed powder into a cylindrical mold and press it into a preform with a diameter of 0.55 × height of 0.3 cm using a hydraulic press at a pressure of 5 MPa.

[0034] (3) HPHT synthesis: The preform was loaded into the boron nitride (BN) sample chamber of a 420-type six-sided top press, and the corresponding pyrophyllite device was assembled. The pressure was increased to 5 GPa within 10 min and held for 2 min to stabilize the pressure. The temperature was increased to 1653 K at a heating rate of 100 K / min and held for 3 h. After the holding period, the temperature was quenched to room temperature. Then, the pressure was slowly reduced to atmospheric pressure within 15 min to avoid cracking of the material due to sudden pressure change, thus preparing La 0.9 Y 0.1 O-block.

[0035] (5) Post-processing: La 0.9 Y 0.1 Use an agate knife to scrape off any remaining BN and impurities from the surface of the O block, then transfer it to a glove box for storage.

[0036] Example 2La 0.95 Y 0.05 Preparation of O-block The difference between this embodiment and embodiment 1 is that in step (2), 0.197g La2O3, 0.095g lanthanum metal and 0.011g Y2O3 are weighed according to the ratio.

[0037] Example 3 LaO 0.5 N 0.5 Preparation of bulk materials (1) Raw material pretreatment: La2O3 was calcined at 1273 K in an air atmosphere for 10 h to remove adsorbed water and trace impurities on the surface; after calcination, it was transferred to a glove box filled with argon; metallic La and lanthanum nitride were directly placed into the glove box.

[0038] (2) Mixing and pressing: Weigh 0.105g La2O3, 0.154g lanthanum nitride and 0.045g metallic lanthanum (5% excess) according to the ratio and put them into an agate mortar. Grind for 35min until the particle size is ≤3μm to ensure that the raw materials are mixed evenly. Put the evenly mixed powder into a cylindrical mold and press it into a preform with a diameter of 0.5×height of 0.3cm using a hydraulic press at 5 MPa.

[0039] (3) HPHT synthesis: The preform was loaded into the boron nitride (BN) sample chamber of a 420-type six-sided press, and the corresponding pyrophyllite device was assembled. The pressure was increased to 5 GPa within 10 min and held for 2 min to stabilize the pressure. The temperature was increased to 1653 K at a heating rate of 100 K / min and held for 3 h. After the holding period, the temperature was quenched to room temperature. Then, the pressure was slowly reduced to atmospheric pressure within 15 min to avoid cracking of the material due to sudden pressure change, thus preparing LaO 0.5 N 0.5 Block.

[0040] (5) Post-processing: LaO 0.5 N 0.5 Use an agate knife to scrape off any remaining BN and impurities from the surface of the block, then transfer it to a glove box for storage.

[0041] Example 4 LaO 0.34 N 0.66 Preparation of bulk materials The difference between this embodiment and embodiment 3 is that in step (2), 0.072g La2O3, 0.031g metallic lanthanum, and 0.197g lanthanum nitride are weighed according to the ratio to prepare LaO2O3. 0.34 N 0.66 Block.

[0042] Comparative Example 1La 0.85 Y 0.15 Preparation of O-block The difference between this comparative example and Example 1 is that in step (2), 0.171g La2O3, 0.098g metallic lanthanum, and 0.034g Y2O3 are weighed according to the ratio to prepare La 0.85 Y 0.15 O-block.

[0043] Comparative Example 2La 0.8 Y 0.2 Preparation of O-block The difference between this comparative example and Example 1 is that in step (2), 0.157g La2O3, 0.099g lanthanum metal, and 0.047g Y2O3 are weighed according to the ratio to prepare La 0.8 Y 0.2 O-block.

[0044] Comparative Example 3La0.67 Y 0.33 Preparation of O-block The difference between this comparative example and Example 1 is that in step (2), 0.119g La2O3, 0.100g lanthanum metal, and 0.081g Y2O3 are weighed according to the ratio to prepare La 0.67 Y 0.33 O-block.

[0045] Test case (1) The bulk materials prepared in Examples 1-4, Comparative Examples 1-3, and undoped LaO bulk materials were tested using an X-ray diffractometer (MiniFlex 600, Rigaku, Japan) and a physical property measurement system (PPMS-9T).

[0046] (2) Figure 1 XRD patterns of the bulk materials prepared in Examples 1-4 and Comparative Examples 1-3, and undoped LaO bulk materials (prepared according to the method in Example 1, except that Y2O3 was not added). Figure 1 It can be seen that the La prepared in Example 1 0.9 Y 0.1 The XRD pattern of the O bulk material showed a pure NaCl-type structure, space group Fm-3m, lattice parameter a = 5.129 Å, and impurity content of approximately 3.9%. Example 2 prepared La... 0.95 Y 0.05 The XRD pattern of the bulk O showed a pure NaCl-type structure with a lattice parameter a = 5.138 Å and an impurity content of approximately 3.5%. Examples 3-4 show the LaO prepared... 0.5 N 0.5 Block and LaO 0.34 N 0.66 The bulk is essentially a pure phase with lattice parameters a The lattice parameters are 5.193 Å and 5.235 Å, respectively. The XRD pattern of the undoped LaO bulk shows that it is a pure NaCl phase with a lattice parameter a = 5.145 Å and an impurity content of 2.7%.

[0047] La prepared in comparative examples 1-3 0.85 Y 0.15 O block, La 0.8 Y 0.2 O block and La 0.67 Y 0.33 The XRD diffraction peaks of the bulk O material broadened, and LaYO3 impurity peaks appeared. Specifically, the La prepared in Comparative Example 1... 0.85 Y 0.15 The impurity content of the O bulk material was approximately 6.1%, while the La prepared in Comparative Example 2... 0.8 Y 0.2The impurity content of the O bulk material was approximately 10.7%, while the La prepared in Comparative Example 3... 0.67 Y 0.33 The impurity content of the O block is approximately 7.2%.

[0048] (3) Figure 2 The figures show the magnetization and resistance test results for the bulk materials prepared in Examples 1-2 and Comparative Example 1, and the undoped LaO bulk material; wherein, Figure 2 In the figure, 'a' represents the magnetization intensity test diagram of the aforementioned bulk material under an applied magnetic field of 20 Oe. Figure 2 As can be seen from this, all of these samples exhibit diamagnetic transition.

[0049] Figure 2 In Figure 'b', the magnetization intensity test diagram of the bulk material prepared in Example 1 under different applied magnetic fields is shown. Figure 2 As shown in b, the diamagnetic transition temperature decreases with the increase of the applied magnetic field. When it increases to 2T, the diamagnetic phenomenon almost disappears, similar to that of type II superconductivity. Figure 2 In the figure, 'c' represents the resistivity variation with temperature of the bulk materials prepared in Examples 1-2 and Comparative Example 1, and the undoped LaO bulk material. Figure 2 As can be seen from c, the resistance of Comparative Example 1 can never be reduced to zero, indicating that the doping has reached its limit under these conditions. Figure 2 d in Figure 2 A magnified view of the low-temperature region of c. (From...) Figure 2 It can be seen that the La prepared in Example 1 0.9 Y 0.1 O block T C =6.9K, superconducting volume close to 100%. La prepared in Example 2 0.95 Y 0.05 O block T C = 6.57K, superconducting volume close to 100%. Undoped LaO bulk T C = 6.05K, superconducting volume close to 100%. La prepared in Comparative Example 1 0.85 Y 0.15 O block T C =6.62K.

[0050] Figure 3 These are magnetization intensity test images of the bulk materials prepared in Examples 3-4. Figure 3 It can be seen that the LaO prepared in Example 3 0.5 N 0.5 T of the block C = 7K, superconducting volume close to 1.6%; LaO prepared in Example 4 0.34 N 0.66 Block T C = 5.7K, superconducting volume is close to 1.5%.

[0051] The foregoing examples are merely illustrative, used to explain some features of the method described in this invention. The appended claims are intended to claim the broadest possible scope, and the embodiments presented herein are demonstrated by the applicant's actual experimental results. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the invention. Some numerical ranges used in the claims also include sub-ranges within them, and variations within these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A method for preparing a single-ion-doped bulk lanthanum oxide material, characterized in that, Includes the following steps: S1. Lanthanum oxide, metallic lanthanum, and a doping ion source are mixed and pressed into a preform in an inert gas atmosphere; the doping ion source is selected from a yttrium source or a nitrogen source; S2. The preform is placed in a multi-faceted press, pressurized to 4.5-5.5 GPa, and held at that pressure; then heated to 1473-1653 K at a rate of 100-200 K / min and held at that temperature to prepare a single-ion doped lanthanum oxide bulk material La. 1-x Y x O or LaO 1- y N y ; Where x is selected from 0.04 to 0.11; y is selected from 0.40 to 0.

70.

2. The preparation method according to claim 1, characterized in that, In step S1, the yttrium source is yttrium oxide; and / or the nitrogen source is selected from lanthanum nitride.

3. The preparation method according to claim 1, characterized in that, In step S1, the pressure for mixing and pressing is 5-8 MPa.

4. The preparation method according to claim 1, characterized in that, In step S1, the purity of the lanthanum oxide is ≥99.99%; and / or the purity of metallic lanthanum is ≥99.7%; and / or the purity of the doped ion source is ≥99.7%.

5. The preparation method according to claim 1, characterized in that, In step S2, the rate of pressure increase is 0.3-1 GPa / min.

6. The preparation method according to claim 1, characterized in that, In step S2, the pressure holding time is 1-5 minutes.

7. The preparation method according to claim 1, characterized in that, In step S2, the heat preservation time is 2-4 hours.

8. The preparation method according to claim 1, characterized in that, x is selected from 0.05-0.10; y is selected from 0.45-0.

66.

9. The single-ion doped lanthanum oxide bulk material prepared by the preparation method according to any one of claims 1-8.

10. The application of the single-ion doped lanthanum oxide bulk material according to claim 9 in superconducting devices.

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