High-entropy manganate multiferroic ceramic material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of novel ceramic materials, in particular to a high-entropy manganate multiferroic ceramic material and a preparation method and application thereof. The chemical formula of the high-entropy manganate multiferroic ceramic material is (Gd < x > Sm < x > Eu < x > Tb < x > Dyx) MnO < 3 >, and x is 0.2. The preparation method comprises the following steps: taking Gd2O3, Sm2O3, Eu2O3, Tb2O3, Dy2O3 and Mn3O4 according to metal ions Gd, Sm, Eu, Tb, Dy and Mn in a molar ratio of 0.2: 0.2: 0.2: 0.2: 0.2: 0.2: 0.2: 1, and carrying out batching; then ball milling and ultrasonic dispersion are combined, and first-time pre-sintering, second-time pre-sintering, tabletting and sintering are performed to prepare the ceramic material. The pure-phase high-entropy manganate multiferroic ceramic material is prepared by carrying out high-entropy design on a rare earth position of rare earth manganate, uniformly mixing five elements of Gd, Sm, Eu, Tb and Dy by utilizing a ball milling process and adopting a solid-phase reaction method, so that a novel functional ceramic material which has excellent magnetoelectric performance and is suitable for the fields of magnetoelectric sensing and information storage is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel ceramic materials, and relates to a high-entropy manganate multiferroic ceramic material, a preparation method thereof, and an application thereof. Background Art

[0002] Multiferroic materials simultaneously possess multiple ferroic properties such as ferroelectricity and ferromagnetism, and due to the coupling effects between different ferroic properties, they have new physical properties such as magnetoelectric effect and exchange bias effect, showing great application prospects in fields such as novel magnetoelectric devices. Rare-earth manganates, due to their unique electromagnetic properties, exhibit important application values in fields such as magnetoelectric sensing, information storage, and spin devices. Traditional rare-earth manganates are usually compounds of a single rare-earth element, and their properties are limited to a certain extent. For example, rare-earth manganates of a single rare-earth element have deficiencies in the comprehensive optimization of magnetoelectric transition temperature, magnetoelectric coupling performance, electrical properties, and magnetic properties, and it is difficult to meet the growing demands of modern information technology for high-performance magnetoelectric materials.

[0003] "High entropy" is a new material design theory that has emerged in recent years. High-entropy ceramics, as a new type of ceramic materials that have emerged in recent years, are a class of inorganic non-metallic materials formed by the mutual solid solution of multiple components (generally more than 5); the "high-entropy effect" usually endows materials with four core effects, namely the high-entropy effect in thermodynamics, the lattice distortion effect in crystallography, the retarded diffusion effect in kinetics, and the "cocktail" effect in performance; compared with traditional ceramic materials, known high-entropy ceramics show obvious differences in composition, structure, or performance, breaking through the design limitations of simple component compositions, and providing broader ideas and guidance for the research and development of new material systems and the optimization of key performance; in rare-earth manganates, high-entropy design is carried out, and by introducing multiple main element elements, it is expected to break through the limitations of the properties of traditional rare-earth manganates, making the ceramic materials have unique microstructures and excellent comprehensive properties. However, at present, the research and reports on high-entropy rare-earth manganate multiferroic ceramic materials are relatively few; exploring the performance optimization of ceramic materials based on the high-entropy strategy has become a hot topic in this field; the synthesis of pure phases is currently a difficulty in the preparation of high-entropy ceramics, and the existence of impurity phases will seriously affect the related properties of high-entropy ceramics, bringing difficulties to their applications. Summary of the Invention

[0004] The present invention provides a high-entropy manganate multiferroic ceramic material, a preparation method thereof, and an application thereof to solve the problems of low magnetoelectric transition temperature, weak magnetism, and weak magnetoelectric coupling of existing manganate ceramic materials.

[0005] According to the first aspect disclosed by the present invention: The present invention provides a high-entropy manganate multiferroic ceramic material, and its chemical formula is: (Gd x Sm x Eu x Tbx Dy x )MnO3, where x is 0.2.

[0006] The beneficial effects of adopting the above technical solution are as follows: The high-entropy manganate multiferroic ceramic material (Gd x Sm x Eu x Tb x Dy x )MnO3 has a single-phase structure, a relatively high magnetic transition temperature, magnetism, and a significant magnetodielectric effect. By equiatomic solid solution of five elements, namely Gd, Sm, Eu, Tb, and Dy, at the rare-earth position of the rare-earth manganate, lattice distortion effects, high ion disorder, and cation vacancy defects are caused, etc., thereby regulating the spin arrangement of Mn 3+ , affecting the interaction between ions, electronic structure, magnetoresistance degree, local electric field inhomogeneity, ion / electron displacement polarization, and charge disorder degree, etc., thereby regulating the magnetism, dielectric property, and magnetodielectric effect of the material, and it is a kind of multifunctional ceramic material with broad application prospects.

[0007] According to the second aspect disclosed by the present invention, the present invention provides a preparation method of a high-entropy manganate multiferroic ceramic material, including:

[0008] (1) Take gadolinium oxide Gd2O3, samarium oxide Sm2O3, europium oxide Eu2O3, terbium oxide Tb2O3, dysprosium oxide Dy2O3, and manganese tetroxide Mn3O4 according to the molar ratio of metal ions Gd:Sm:Eu:Tb:Dy:Mn of 0.2:0.2:0.2:0.2:0.2:1 for batching;

[0009] (2) Add the obtained batching with an organic solvent as a medium and grind and mix evenly, and then perform the first pre-sintering at 950 - 1050 °C;

[0010] (3) Perform the first ball milling on the product of the first pre-sintering, and then perform the second pre-sintering at 1200 - 1300 °C;

[0011] (4) Perform the second ball milling on the product of the second pre-sintering to obtain a powder with refined grains;

[0012] (5) Perform ultrasonic dispersion on the powder with refined grains, and then perform drying and tabletting;

[0013] (6) Sinter the tablet at 1300 - 1500 °C to prepare the high-entropy manganate multiferroic ceramic material.

[0014] The beneficial effects of the present invention adopting the above technical solutions are as follows: By performing high-entropy design on the rare-earth position of rare-earth manganate, using five elements of Gd, Sm, Eu, Tb, and Dy, and the molar content of each element being 0.2, the ball milling process is utilized to achieve uniform mixing of the elements, and the solid-phase reaction method is adopted to prepare a pure-phase high-entropy manganate multiferroic ceramic material, so as to obtain a new functional ceramic material with excellent magnetoelectric properties and suitable for the fields of magnetoelectric sensing and information storage; the preparation process of the present invention is simple, low in cost, environmentally friendly and harmless, and has good repeatability. The obtained ceramic material has a high magnetic transition temperature, a high dielectric constant, and obvious magnetodielectric coupling characteristics, and has broad application prospects in the fields of magnetoelectric sensors, information storage, capacitors, energy converters, and spin devices.

[0015] In a feasible embodiment, in the step (1), the weighed raw materials of gadolinium oxide Gd2O3, samarium oxide Sm2O3, europium oxide Eu2O3, terbium oxide Tb2O3, dysprosium oxide Dy2O3 and manganese tetroxide Mn3O4 are vacuum-dried at 110 - 150 °C and then formulated.

[0016] In a feasible embodiment, in the step (2), the organic solvent is anhydrous ethanol.

[0017] In a feasible embodiment, in the step (2), the first pre-burning time is 20 - 28 h. The grinding rotation speed is 100 - 200 rpm, and the grinding time is 20 - 28 h.

[0018] In a feasible embodiment, in the step (3), the second pre-burning time is 20 - 28 h. The first ball milling rotation speed is 100 - 200 rpm, and the first ball milling time is 1 - 3 h.

[0019] In a feasible embodiment, in the step (4), the second ball milling rotation speed is 300 - 500 rpm, and the second ball milling time is 1 - 3 h.

[0020] In a feasible embodiment, in the step (5), the ultrasonic dispersion frequency is 30 - 60 kHz, the power is 100 - 200 W, the time is 15 - 30 min, and the tabletting pressure is 7 - 12 Mpa.

[0021] In a feasible embodiment, in the step (6), the sintering time is 20 - 28 h.

[0022] The above first pre-burning, second pre-burning and sintering can all be carried out in an air atmosphere.

[0023] The beneficial effects of the present invention adopting the above technical solutions are as follows:

[0024] The present invention pre-fires the ground powder twice (first pre-fire and second pre-fire), the purposes of which are: ① to promote a preliminary chemical reaction between the raw materials to form the main crystal phase of the multiferroic ceramic; ② the two pre-fires can reduce defects and stress in the sample; ③ to promote uniform grain growth, optimize the sintering activity of the powder, and lay the foundation for the subsequent preparation of high-quality ceramics.

[0025] The invention can break the hard agglomeration in the powder and improve the particle dispersibility by ball milling and ultrasonic dispersion of the products after two pre-sintering, thereby providing uniform powder raw materials for subsequent molding and sintering processes.

[0026] The present invention presses the powder into a disc-shaped sample under a tabletting pressure of 7-12Mpa before sintering.

[0027] According to a third aspect disclosed in the present invention, the present invention provides applications of high entropy manganate multiferroic ceramic materials in magnetoelectric sensors, information storage, capacitors and energy converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The GdMnO3 prepared in Examples 1 to 4 of the present invention and the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )XRD pattern of MnO3 ceramic sample;

[0029] Figure 2 The GdMnO3 prepared in Examples 1 to 4 of the present invention and the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )Magnetic-temperature curve of MnO3 ceramic sample;

[0030] Figure 3 The GdMnO3 prepared in Examples 1 to 4 of the present invention and the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 ) Magnetic hysteresis loop of MnO3 ceramic sample (T = 30K);

[0031] Figure 4 The GdMnO3 prepared in Examples 1 to 4 of the present invention and the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy0.2 ) Dielectric-frequency curves of MnO3 ceramic samples; where (a) corresponds to the dielectric constant; (b) corresponds to the dielectric loss.

[0032] Figure 5 For the GdMnO3 prepared in Example 1 of the present invention and (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 ) Variation diagram of the magnetodielectric coefficient MD with magnetic field at 1000 Hz for MnO3 ceramic samples. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other implementation manners obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope protected by the present invention.

[0034] Example 1

[0035] Using the ball milling solid-phase reaction method, prepare GdMnO3 multiferroic ceramic materials:

[0036] (1) Weigh the dried raw materials MnO2 (purity 99.99%) and Gd2O3 (purity 99.99%), and mix them according to the molar ratio of Mn:Gd of 1:1.

[0037] (2) Using anhydrous ethanol as a medium, grind the raw materials weighed in step (1) in a ball mill for 24 h, with a ball milling speed of 150 rpm, and pre-burn the uniformly ground powder in an air atmosphere at 1000 °C for the first time, with the first pre-burning time being 24 h.

[0038] (3) Crush the pre-burned product obtained in step (2), and place it in the ball mill again for ball milling for 2 h, with a ball milling speed of 150 rpm. Then pre-burn the milled powder in an air atmosphere at 1250 °C for the second time, with the second pre-burning time being 24 h.

[0039] (4) Crush the product obtained in step (3), put it into the ball mill for ball milling for 2 h, with a ball milling speed of 350 rpm, to obtain a powder with refined grains.

[0040] (5) Place the powder with refined grains prepared in step (4) into an ultrasonic dispersion device, set the frequency of the ultrasonic dispersion device to 40 kHz, the power to 150 W, and the time to 20 minutes to break the particle agglomeration; dry the ultrasonically dispersed powder at 120 °C for 12 hours, and then use a tablet press to press it into a shape at a pressure of 10 MPa.

[0041] (6) Sinter the wafers obtained in step (5) in an air atmosphere at 1350 °C for 24 h to obtain the GdMnO3 ceramic material.

[0042] The XRD of the GdMnO3 multiferroic ceramic material sample prepared in Example 1 is as Figure 1 shown. From Figure 1 it is observed that all the diffraction peaks are the same as those of the orthorhombic perovskite structure, showing a single-phase structure and no diffraction peaks of the second phase appear; Figure 2 and Figure 3 and Figure 4 and Figure 5 respectively give the magnetic temperature curve, hysteresis loop, dielectric constant and magnetodielectric coefficient of the GdMnO3 multiferroic ceramic material.

[0043] Example 2

[0044] Using the solid-phase reaction method combined with ball milling process and ultrasonic dispersion, prepare (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 multiferroic high-entropy ceramic material:

[0045] (1) Place the raw materials Mn3O4 (purity 99.99%), Gd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Tb2O3 (purity 99.99%), Dy2O3 (purity 99.99%) in a vacuum drying oven and dry at 120 °C for 12 hours. After drying, the raw materials Gd2O3, Sm2O3, Eu2O3, Tb2O3, Dy2O3, Mn3O4 are proportioned according to the molar ratio of metal elements Gd, Sm, Eu, Tb, Dy, Mn of 0.2:0.2:0.2:0.2:0.2:1;

[0046] (2) Take the raw materials weighed according to the stoichiometric ratio in step (1) with absolute ethanol as the medium, grind in a ball mill for 24 h, the ball milling speed is 150 rpm, and then conduct the first pre-sintering in an air atmosphere at 1000 °C for 24 h;

[0047] (3) Crush the pre-sintered product obtained in step (2), place it in a ball mill and ball mill for 2 h, the ball milling speed is 150 rpm, and then conduct the second pre-sintering in an air atmosphere at 1250 °C for 24 h;

[0048] (4) Crush the product obtained in step (3), place it in a ball mill and ball mill for 2 h, and the ball milling speed is 350 rpm to obtain the powder with refined grains;

[0049] (5) Place the powder with refined grains obtained in step (4) into an ultrasonic dispersion device, set the frequency of the ultrasonic dispersion device to 40 kHz, the power to 150 W, and the time to 20 minutes to break particle agglomeration; dry the powder after ultrasonic dispersion at 120 °C for 12 hours, and then use a tablet press to press it into a round tablet under a pressure of 10 MPa;

[0050] (6) Sinter the round tablet obtained in step (5) in an air atmosphere at 1350 °C for 24 h to obtain (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material.

[0051] The XRD of the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material sample prepared in Example 2 is as Figure 1 shown. It is observed from Figure 1 that all diffraction peaks are the same as those of orthorhombic perovskite-structured GdMnO3, showing a single-phase structure without the appearance of diffraction peaks of the second phase; Figure 2 , Figure 3 , Figure 4 , Figure 5 respectively give the magnetic temperature curve, hysteresis loop, dielectric constant and magnetodielectric coefficient of (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 prepared at a sintering temperature of 1350 °C.

[0052] Example 3

[0053] Using the solid-state reaction method combined with ball milling and ultrasonic dispersion, prepare (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 multiferroic high-entropy ceramic material:

[0054] (1) The raw materials Mn3O4 (purity 99.99%), Gd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Tb2O3 (purity 99.99%), Dy2O3 (purity 99.99%) were placed in a vacuum drying oven and dried at 120 °C. After drying, the raw materials Gd2O3, Sm2O3, Eu2O3, Tb2O3, Dy2O3, Mn3O4 were proportioned according to the molar ratio of metal elements Gd, Sm, Eu, Tb, Dy, Mn of 0.2:0.2:0.2:0.2:0.2:1;

[0055] (2) The raw materials weighed according to the stoichiometric ratio in step (1) were ground in a ball mill for 24 h with anhydrous ethanol as the medium and a ball mill rotation speed of 150 rpm, and then pre-fired for the first time at 1000 °C in an air atmosphere for 24 h;

[0056] (3) The pre-fired product obtained in step (2) was crushed, placed in a ball mill and milled for 2 h with a ball mill rotation speed of 150 rpm, and then pre-fired for the second time at 1250 °C in an air atmosphere for 24 h;

[0057] (4) The product obtained in step (3) was crushed, placed in a ball mill and milled for 2 h with a ball mill rotation speed of 350 rpm to obtain a powder with refined grains;

[0058] (5) The powder with refined grains obtained in step (4) was placed into an ultrasonic dispersion device. The frequency of the ultrasonic dispersion device was set to 40 kHz, the power was 150 W, and the time was 20 minutes to break the particle agglomeration; The powder after ultrasonic dispersion was dried at 120 °C for 12 hours, and then pressed into a round tablet under a pressure of 10 MPa using a tablet press;

[0059] (6) The round tablet obtained in step (5) was sintered at 1420 °C in an air atmosphere for 24 h to obtain a (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganate multiferroic ceramic material.

[0060] The XRD of the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganate multiferroic ceramic material sample prepared in Example 3 is as shown in Figure 1 shown, from Figure 1All the observed diffraction peaks are the same as those of orthorhombic perovskite-structured GdMnO3, showing a single-phase structure without the appearance of diffraction peaks of a second phase; Figure 2 and Figure 3 、 Figure 4 、 Figure 5 respectively give the magnetization-temperature curves, hysteresis loops, dielectric constants, and magnetodielectric coefficients of (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 prepared at a sintering temperature of 1420 °C.

[0061] Example 4

[0062] Using the solid-state reaction method combined with ball milling and ultrasonic dispersion, prepare (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 multiferroic high-entropy ceramic materials:

[0063] (1) Place the raw materials Mn3O4 (purity 99.99%), Gd2O3 (purity 99.99%), Sm2O3 (purity 99.99%), Eu2O3 (purity 99.99%), Tb2O3 (purity 99.99%), Dy2O3 (purity 99.99%) in a vacuum drying oven and dry at 120 °C for 12 hours. After drying, the raw materials Gd2O3, Sm2O3, Eu2O3, Tb2O3, Dy2O3, Mn3O4 are proportioned according to the molar ratio of metal elements Gd, Sm, Eu, Tb, Dy, Mn of 0.2:0.2:0.2:0.2:0.2:1;

[0064] (2) Take the raw materials weighed according to the stoichiometric ratio in step (1) with absolute ethanol as the medium, grind in a ball mill for 24 h, the ball milling speed is 150 rpm, and then conduct the first pre-sintering at 1000 °C in an air atmosphere for 24 h;

[0065] (3) Crush the pre-sintered product obtained in step (2), place it in a ball mill and ball mill for 2 h, the ball milling speed is 150 rpm, and then conduct the second pre-sintering at 1250 °C in an air atmosphere for 24 h;

[0066] (4) Crush the product obtained in step (3), place it in a ball mill and ball mill for 2 h, the ball milling speed is 350 rpm, to obtain a powder with refined grains;

[0067] (5) Place the powder with refined grains obtained in step (4) into an ultrasonic dispersion device, set the frequency of the ultrasonic dispersion device to 40 kHz, the power to 150 W, and the time to 20 minutes to break the particle agglomeration; dry the powder after ultrasonic dispersion at 120 °C for 12 hours, and then use a tablet press to press it into a round tablet under a pressure of 10 MPa;

[0068] (6) Sinter the round tablet obtained in step (5) in an air atmosphere at 1500 °C for 24 h to obtain the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material.

[0069] The XRD of the sample of the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material prepared in Example 4 is as Figure 1 shown. It can be observed from Figure 1 that all the diffraction peaks are the same as those of orthorhombic perovskite-structured GdMnO3, showing a single-phase structure without the diffraction peaks of a second phase appearing; Figure 2 , Figure 3 , Figure 4 , Figure 5 respectively give the magnetic temperature curve, hysteresis loop, dielectric constant and magnetodielectric coefficient of (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 prepared at a sintering temperature of 1500 °C.

[0070] To study the phase structure of the high-entropy manganite multiferroic ceramic material prepared by the method of the present invention, X-ray diffractometer (XRD) was used to perform phase analysis on the samples obtained in Examples 1-4, and the results are shown in Figure 1 as shown; it can be seen from Figure 1 that the prepared (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material has the same orthorhombic perovskite structure as GdMnO3 and no second phase is generated, indicating that the pure-phase high-entropy manganite multiferroic ceramic material can be obtained by using the method of the present invention; compared with GdMnO3, (Gd 0.2 Sm 0.2 Eu 0.2 Tb0.2 Dy 0.2 The diffraction peaks of (Gd

[0071] To study the magnetic properties of the high-entropy manganite multiferroic ceramic materials prepared by the method of the present invention, the magnetic temperature curve and the hysteresis loop of the samples of Examples 1-4 were measured by using the PPMS comprehensive physical property test system of Quantum Design Corporation, and the results are shown in Figure 2 and Figure 3 as shown. It can be seen from Figure 2 that GdMnO3 shows a weak ferromagnetic transition at ~23 K and the magnetic order of Gd appears at ~7 K; (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite ceramic shows an antiferromagnetic transition at ~36.0 K, and the subsequent magnetization curve shows that the sample has a ferrimagnetic structure; when the temperature increases from 1350 °C to 1420 °C, the transition temperature of the sample increases from 36.0 K to 45.6 K, and when the temperature increases from 1420 °C to 1500 °C, the magnetic transition temperature of the sample decreases from 45.6 K to 42.1 K. Thus, compared with the GdMnO3 sample, the magnetic transition temperature of (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 is greatly improved. It can be seen from Figure 3 that all GdMnO3 shows antiferromagnetism at 30 K, and (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite ceramics show the characteristics of a typical hysteresis loop and are ferromagnetic. The main reasons for the enhanced magnetism are as follows:

[0072] (1) High entropy leads to the coexistence of ions with different radii in the lattice, causing severe lattice distortion. This distortion not only increases the disorder degree of the material but also forms a local stress field, affecting the electron spin arrangement;

[0073] (2) The high-entropy effect can also make the electronic structure of the material more complex and diverse, change the electron cloud distribution, lead to the change of the state of spin electrons, and thus generate a net magnetic moment, which macroscopically shows enhanced magnetism;

[0074] (3) The magnetic contributions of different elements are superimposed or coupled with each other to form an overall enhanced magnetic effect.

[0075] When the temperature increases from 1350 °C to 1420 °C, the magnetization intensity of the sample increases. When the temperature increases from 1420 °C to 1500 °C, the magnetization intensity of the sample slightly decreases. It can be seen from the above that high entropy can increase the magnetic transition temperature, magnetization type and magnetization intensity of manganates, and an appropriate sintering temperature also helps to improve the magnetism of the material.

[0076] In order to study the dielectric properties of the high-entropy manganate multiferroic ceramic materials prepared by the method of the present invention, an Agilent 4294A precision impedance analyzer was used to measure the dielectric properties of the samples of Examples 1-4. The results are shown in Figure 4 shown. As can be seen from Figure 4 (a), the GdMnO3 sample has good dielectric frequency stability, and high entropy significantly increases the dielectric constant of manganates; at a test frequency of 1 MHz, the dielectric constant of the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 sample prepared at 1500 °C is 183.3, which is 3.77 times that of the undoped GdMnO3 dielectric constant (48.6). The reasons are as follows: (1) High entropy leads to serious lattice distortion in manganates, destroys the lattice symmetry, increases the inhomogeneity of the local electric field, and thus enhances the polarization ability of the material; (2) The local stress field generated by lattice distortion will change the ionic displacement polarization and electron cloud distribution, thereby improving the dielectric response; (3) The introduction of multiple metal elements increases the charge disorder degree, resulting in changes in the local electron state density, and thus enhances the dielectric response. In addition, as shown in Figure 4 (b), the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganate ceramic has a slightly higher dielectric loss than the undoped GdMnO3 at high frequencies, and there is no significant increase. The experimental results show that high entropy can improve the dielectric properties of manganates in the high-frequency region at room temperature.

[0077] In order to study the magnetodielectric properties of the high-entropy manganate multiferroic ceramic materials prepared by the method of the present invention, a precision impedance analyzer produced by Agilent connected to the PPMS of Quatum Design Company was used to measure the magnetodielectric properties of the samples of Examples 1 and 3. The results are shown in Figure 5 shown. As can be seen from Figure 5It can be seen that all samples have the magnetodielectric effect, and the magnetodielectric coefficient (MD = (ε(0) - ε(H)) / ε(0), where ε(H) is the dielectric constant under an applied magnetic field and ε(0) is the dielectric constant in zero field) increases with the increase of the applied magnetic field. (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite ceramics have a significantly higher magnetodielectric coefficient than GdMnO3 samples, which is related to the lattice distortion and high ion disorder caused by high-entropy alloying. They jointly lead to an increase in the magnetoelectric coupling effect of (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy samples. The experimental results show that high-entropy alloying enhances the magnetodielectric effect of manganites.

[0078] In summary, the (Gd 0.2 Sm 0.2 Eu 0.2 Tb 0.2 Dy 0.2 )MnO3 high-entropy manganite multiferroic ceramic material provided by the present invention can well optimize the magnetic, dielectric and magnetodielectric properties of manganite ceramic materials through the lattice distortion and high ion disorder effects caused by high-entropy alloying, and is a new type of multiferroic material that is expected to be further studied and explored.

Claims

1. A high-entropy manganate multiferroic ceramic material, characterized in that, Its chemical formula is: (Gd x Sm x Eu x Tb x Dy x )MnO3, where x is 0.

2.

2. A preparation method of a high-entropy manganate multiferroic ceramic material, characterized in that Including: (1) Take gadolinium oxide Gd2O3, samarium oxide Sm2O3, europium oxide Eu2O3, terbium oxide Tb2O3, dysprosium oxide Dy2O3 and manganese tetroxide Mn3O4 according to the molar ratio of metal ions Gd, Sm, Eu, Tb, Dy, Mn of 0.2:0.2:0.2:0.2:0.2:1 for batching; (2) Add the obtained batch to an organic solvent as a medium and grind and mix evenly, and then carry out the first pre-sintering at 950 - 1050 °C; (3) Carry out the first ball milling on the product of the first pre-sintering, and then carry out the second pre-sintering at 1200 - 1300 °C; (4) Carry out the second ball milling on the product of the second pre-sintering to obtain a powder with refined grains; (5) Carry out ultrasonic dispersion on the powder with refined grains, and then carry out drying and tabletting; (6) Sinter the tablet at 1300 - 1500 °C to prepare a high-entropy manganate multiferroic ceramic material.

3. The preparation method of the high-entropy manganite multiferroic ceramic material according to claim 2, characterized in that, In step (1), the weighed gadolinium oxide Gd2O3, samarium oxide Sm2O3, europium oxide Eu2O3, terbium oxide Tb2O3, dysprosium oxide Dy2O3 and manganese tetroxide Mn3O4 are vacuum dried at 110 - 150 °C, and then batching is carried out.

4. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 5, characterized in that, In step (2), the organic solvent is anhydrous ethanol.

5. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 2, characterized in that, In step (2), the first pre-sintering time is 20 - 28 h.

6. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 2, characterized in that, In step (3), the second pre-sintering time is 20 - 28 h.

7. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 2, characterized in that, In step (6), the sintering time is 20 - 28 h.

8. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 2, characterized in that, In step (2), the grinding speed is 100 - 200 rpm, and the grinding time is 20 - 28 h; In step (3), the first ball milling speed is 100 - 200 rpm, and the first ball milling time is 1 - 3 h; In step (4), the second ball milling speed is 300 - 500 rpm, and the second ball milling time is 1 - 3 h.

9. The preparation method of the high-entropy manganate multiferroic ceramic material according to claim 2, characterized in that, In step (5), the ultrasonic dispersion frequency is 30 - 60 kHz, the power is 100 - 200 W, and the time is 15 - 30 min; the tabletting pressure is 7 - 12 Mpa.

10. Application of the high-entropy manganate multiferroic ceramic material according to claim 1 in magnetoelectric sensors, information storage, capacitors and energy converters.

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