A high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material, a preparation method and application thereof

Abstract

The application discloses a high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material, a preparation method and application thereof, and belongs to the field of high-temperature thermosensitive sensors, and aims to solve the stability problem of a chromium-based perovskite in long-term use at high temperature, in particular the problem of electrical property decrease caused by Cr element volatilization. The negative temperature coefficient thermosensitive ceramic material is prepared by mixing raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide and chromium trioxide respectively with dysprosium trioxide, holmium trioxide, yttrium trioxide and erbium trioxide according to a stoichiometric ratio, and then performing wet ball milling, drying, powder calcination, cold isostatic pressing and high-temperature sintering, so that a perovskite structure (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3 thermosensitive ceramic material is obtained, wherein M is Dy, Ho, Y or Er. The electrical performance parameters of the thermosensitive ceramic material are as follows: B 25℃ / 1500℃ =1927~2011 K, ρ 1500℃ =1.29×10 2 ~1.60×10 2 Ω·cm, and the thermosensitive ceramic material exhibits good high-temperature aging stability at high temperature (after aging for 500 hours at 1500 DEG C, the resistance drift rates are all less than 4.6%).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-temperature thermal sensors, in particular to a high-entropy rare earth chromate negative temperature coefficient thermal sensitive ceramic material, a preparation method and application thereof. BACKGROUND

[0002] In recent years, the demand for miniaturization and economy of temperature sensors in various fields has been driven by national industrial adjustment and technological upgrading. Compared with expensive noble metal thermocouples, negative temperature coefficient (NTC) thermistors have attracted widespread attention in temperature detection and circuit protection applications, and the corresponding demand has also increased. At the same time, with the continuous progress of technology in the fields of aerospace, national defense science and technology, etc., the high-temperature performance requirements of equipment are also increasing. This requires NTC thermistors to meet higher upper temperature limits while maintaining excellent high-temperature aging stability.

[0003] Currently, common NTC materials (such as spinel oxides) have poor phase stability and sensitivity at high temperatures above 300℃, limiting their application range. Currently, the research focus of NTC materials has shifted to chromium-based perovskites and their composite materials. Chromium-based perovskite ceramics are suitable for a wide temperature range (25℃~900℃) and have adjustable electrical properties, but at high temperatures, element volatilization easily occurs, making it difficult to form a dense microstructure during sintering and causing continuous resistance changes, thereby affecting high-temperature reliability and production feasibility. Although composite ceramics of high-resistance phase oxides and low-resistance phase perovskites can theoretically be used for high-temperature NTC materials, the two-phase interpenetration problem in actual applications causes large resistance drift at high temperatures.

[0004] Therefore, there is an urgent need to develop new NTC materials to meet the increasingly high performance standards at high temperatures. SUMMARY

[0005] The purpose of the present application is to provide a high-entropy rare earth chromate negative temperature coefficient thermal sensitive ceramic material, a preparation method and application thereof, to solve the stability problems of chromium-based perovskite and its composite thermal sensitive ceramics during long-term use at high temperatures, especially the problem of electrical property degradation caused by Cr element volatilization. The high-entropy rare earth chromate negative temperature coefficient thermal sensitive ceramic material of the present application has an ultra-wide temperature range suitable for 25~1500℃, and exhibits excellent aging stability at the upper limit temperature of 1500℃.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A high-entropy rare earth chromate negative temperature coefficient thermal sensitive ceramic material, whose chemical formula is (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6Gd1 / 6 M 1 / 6 )CrO3, wherein M is Dy, Ho, Y or Er.

[0008] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has a negative temperature coefficient characteristic in the range of 25 DEG C to 1500 DEG C.

[0009] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has a temperature range of 25 DEG C to 1500 DEG C.

[0010] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has the following electrical performance parameters: B 25℃ / 1500℃ =1927-2011 K, p 1500℃ =1.29*10 2 ~1.60*10 2 Ω*cm.

[0011] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has a resistance drift rate of less than 4.6% after aging at 1500 DEG C for 500 hours.

[0012] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is prepared by mixing and sintering raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, chromium trioxide and M oxide according to the molar ratio of the chemical formula; the M oxide is dysprosium trioxide, holmium trioxide, yttrium trioxide or erbium trioxide.

[0013] The preparation method of the aforementioned high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is prepared by mixing and sintering raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, chromium trioxide and M oxide according to the molar ratio of the chemical formula; the M oxide is dysprosium trioxide, holmium trioxide, yttrium trioxide or erbium trioxide.

[0014] Comprising the following steps:

[0015] a. According to the substance amount ratio of La:Nd:Sm:Eu:Gd:M:Cr=1:1:1:1:1:1:6, lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, M oxide and chromium trioxide are respectively taken and mixed to obtain an initial mixture; the initial mixture is ground to obtain a precursor powder; wherein M is Dy, Ho, Y or Er, and the M oxide is dysprosium trioxide, holmium trioxide, yttrium trioxide or erbium trioxide;

[0016] b. The precursor powder obtained in step a is calcined and ground to obtain a chromate powder;

[0017] c. dry-pressing the chromate salt powder obtained in step b to obtain a dry-pressed block; cold isostatic pressing the dry-pressed block to obtain a cold isostatic pressed block; sintering the cold isostatic pressed block to obtain the high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material.

[0018] In step a, the process of grinding the initial mixture is as follows: wet ball milling the initial mixture, then drying, and then grinding to obtain the precursor powder.

[0019] In step a, the liquid phase dispersant for wet ball milling is deionized water, and the grinding medium is agate ball.

[0020] In step a, the process of grinding the initial mixture is as follows: wet ball milling the initial mixture, drying the slurry after wet ball milling, and then grinding the dried material to obtain the precursor powder.

[0021] In step a, the initial mixture is wet ball milled for 8-10 hours using liquid phase assisted three-dimensional vibration ball milling; the drying temperature is 80-120°C; and the dried material is manually ground in an agate mortar for 1-3 hours.

[0022] In step b, the calcination temperature is 900-1300°C, and the calcination time is 2-5 hours; after calcination, the material is ground into powder to obtain the chromate salt powder.

[0023] In step b, the precursor powder obtained in step a is placed in a corundum crucible for calcination.

[0024] In step b, the material is manually ground for 1-5 hours after calcination to obtain the chromate salt powder (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6Gd 1 / 6 M 1 / 6 )CrO3, wherein M is Dy, Ho, Y, or Er.

[0025] In step c, the pressure for dry pressing is 15-18 kg / cm 2 .

[0026] In step c, the chromate salt powder obtained in step b is dry-pressed using a single-shaft oil press at a pressure of 15-18 kg / cm 2 to obtain a dry-pressed block.

[0027] In step c, the dry pressing time is 0.5-10 minutes.

[0028] In step c, the dry-pressed block is cold isostatic pressed at a pressure of 270-300 MPa to obtain a cold isostatic pressed block.

[0029] In step c, the pressure holding time of the cold isostatic pressing is 3-20 minutes.

[0030] In step c, the dry-pressed block is cold isostatic pressed at a pressure of 270-300 MPa for 3-20 minutes to obtain a cold isostatic pressed block.

[0031] In step c, the sintering temperature is 1500-1600℃, and the sintering time is 10-12 hours.

[0032] A high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material, whose chemical formula is (La 1 / 6 Nd 1 / 6Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3, wherein M is Dy, Ho, Y or Er.

[0033] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is used to prepare a high-temperature thermosensitive sensor.

[0034] The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is used to prepare a negative temperature coefficient thermosensitive sensor.

[0035] As described above, in order to improve the stability and reliability of the chromium-based perovskite and the composite thermosensitive ceramic in a high-temperature environment, the present application provides a new high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material, a preparation method and application thereof. The chemical formula of the rare earth chromate negative temperature coefficient thermosensitive ceramic material is (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3 (M=Dy, Ho, Y or Er), which has a negative temperature coefficient characteristic at 25-1500℃ and is a high-entropy rare earth chromate high-temperature negative temperature coefficient thermosensitive ceramic material, i.e., a new high-temperature thermosensitive ceramic with a 25-1500℃ ultra-wide working temperature range and excellent aging stability. The series of negative temperature coefficient thermosensitive materials are prepared by mixing and sintering raw materials chromium sesquioxide, lanthanum sesquioxide, neodymium sesquioxide, samarium sesquioxide, europium sesquioxide, gadolinium sesquioxide, chromium sesquioxide and oxides of M according to the molar ratio of the chemical formula (the oxides of M are dysprosium sesquioxide, holmium sesquioxide, yttrium sesquioxide and erbium sesquioxide).

[0036] The inventors have found that a high-entropy rare earth chromate (La1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 CrO3 (M=Dy, Ho, Y, or Er) exhibits a significant negative temperature coefficient characteristic within a temperature range of 25℃ to 1500℃. This type of high-entropy material displays an ultra-wide testing temperature range, with the highest temperature limit reaching 1500℃. Simultaneously, due to its entropy-stable structure, it exhibits excellent high-temperature aging stability. The resistance drift rate of the prepared ceramic material at 1500℃ was measured in relation to aging time. The experimental results show that the resistance drift rate is less than 4.6% after 500 hours of aging, making it suitable for manufacturing long-life, high-temperature negative temperature coefficient thermistors. The high-entropy rare-earth chromate of this application forms a high-entropy effect through the synergistic effect of multiple principal elements, thermodynamically improving the stability of the high-temperature phase and structure. Severe lattice distortion reduces thermal conductivity and the material constant B value, thereby expanding the application temperature range. Simultaneously, the hysteresis diffusion effect of the high-entropy ceramic brings excellent oxidation resistance, making it suitable for different oxygen atmospheres. This material exhibits stable high-temperature electrical properties and high linear correlation, making it suitable for manufacturing thermistor devices in high-temperature environments.

[0037] In summary, this application provides a series of novel high-entropy rare-earth chromate negative temperature coefficient thermistor ceramic materials with an ultra-wide operating temperature range of 25℃ to 1500℃ and excellent aging stability, their preparation methods, and their applications in the field of semiconductor sensors. The high-entropy rare-earth chromate negative temperature coefficient thermistor ceramic materials of this application are prepared by mixing lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, oxides of M, and chromium trioxide in a stoichiometric ratio, followed by wet ball milling, drying, powder calcination, dry pressing, cold isostatic pressing, and high-temperature sintering to obtain a perovskite structure (La... 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 CrO3 thermistor ceramic material, where M is Dy, Ho, Y, or Er. Its electrical performance parameters are: B 25℃ / 1500℃ =1927~2011 K, ρ 1500℃ =1.29×10 2 ~1.60×10 2 The resistivity (Ω·cm) exhibits excellent high-temperature aging stability (resistivity drift rate is less than 4.6% after aging at 1500℃ for 500 hours). Therefore, the high-entropy rare-earth chromate of this invention is a high-temperature negative temperature coefficient thermistor ceramic material with a high upper limit of operating temperature, an ultra-wide applicable temperature range, and excellent aging stability.

[0038] Due to the adoption of the above technical solutions, the application has the following beneficial effects:

[0039] (1) The thermosensitive material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3 (M = Dy, Ho, Y or Er) has NTC characteristics in the temperature range of 25-1500 ℃, has a wide test temperature range and a high upper limit of working temperature.

[0040] (2) The thermosensitive material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3 (M = Dy, Ho, Y or Er) has a resistance drift rate of less than 4.6% after aging for 500 hours at 1500 ℃, and exhibits excellent high-temperature aging stability.

[0041] (3) The thermosensitive material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3 (M = Dy, Ho, Y or Er) has a high resistivity in a high-temperature environment, which ensures the accuracy of measurement. BRIEF DESCRIPTION OF DRAWINGS

[0042] The application will be described by way of example and with reference to the accompanying drawings, in which:

[0043] Figure 1 is a graph of the relationship between the resistivity of the (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 )CrO3 ceramic material and temperature.

[0044] Figure 2 is a graph of the relationship between the resistivity of the (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 )CrO3 ceramic material and temperature.

[0045] Figure 3 is a graph of the relationship between the resistivity of the (La 1 / 6 Nd1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 Resistivity vs. temperature of CrO3 ceramic material.

[0046] Figure 4 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Er 1 / 6 Resistivity vs. temperature of CrO3 ceramic material.

[0047] Figure 5 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 Resistivity drift vs. aging time at 1500°C of CrO3 ceramic material.

[0048] Figure 6 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 Resistivity drift vs. aging time at 1500°C of CrO3 ceramic material.

[0049] Figure 7 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 Resistivity drift vs. aging time at 1500°C of CrO3 ceramic material.

[0050] Figure 8 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Er 1 / 6 Resistivity drift vs. aging time at 1500°C of CrO3 ceramic material.

[0051] Figure 9 (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd1 / 6 Dy 1 / 6 )CrO3, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 )CrO3, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 )CrO3, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Er 1 / 6 The resistivity-temperature relationship summary chart of the ceramic material of (La DETAILED DESCRIPTION

[0052] All features disclosed in this specification, and / or all steps of any methods or processes disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0053] Any feature disclosed in this specification, unless stated otherwise, can be replaced by any equivalent or similar feature.

[0054] Example 1

[0055] In this embodiment, the preparation process of the high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 )CrO3 is as follows.

[0056] a. According to the molar ratio of La:Nd:Sm:Eu:Gd:Dy:Cr = 1:1:1:1:1:1:6, the oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, dysprosium trioxide and chromium trioxide were weighed and mixed to obtain an initial mixture. The initial mixture was placed in a ball mill tank, agate was used as the ball milling medium, and deionized water was used as the dispersion medium. The liquid phase assisted three-dimensional vibration wet ball milling was carried out for 8 hours. Then, the slurry after wet milling was dried at a temperature of 80℃. After that, it was taken out and placed in an agate mortar, and manually ground for 1 hour to obtain a precursor powder.

[0057] b. The precursor powder obtained in step a is calcined at 900°C for 2 hours, and then manually ground for 1 hour to obtain a chromate powder.

[0058] c. The chromate powder obtained in step b is dry-pressed into a block using a single-shaft oil press at a pressure of 15 kg / cm 2 for 0.5 minutes, and then cold isostatic pressed at a pressure of 270 MPa for 3 minutes to obtain a cold isostatic pressed block. The cold isostatic pressed block is sintered at a temperature of 1500°C for 10 hours to obtain a high-entropy rare earth chromate high-temperature negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 )CrO3.

[0059] The high-entropy rare earth chromate high-temperature negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6Gd 1 / 6 Dy 1 / 6 )CrO3obtained is subjected to electrical performance testing, and the relationship between resistivity and temperature is shown in Figure 1 . The electrical parameters of the material are B 25℃ / 1500℃ = 1927 K, and p 1500℃ = 1.29 x 10 2 Ω·cm. At the same time, the relationship between the resistance drift rate and aging time of the prepared (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 )CrO3ceramic material at 1500°C is determined, and the test results are shown in Figure 5 .

[0060] Example 2

[0061] In this example, the preparation process of the high-entropy rare earth chromate high-temperature negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 )CrO3is as follows.

[0062] a. Lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, holmium trioxide, and chromium trioxide powders were weighed and mixed according to the molar ratio La:Nd:Sm:Eu:Gd:Ho:Cr=1:1:1:1:1:1:6 to obtain an initial mixture. The initial mixture was placed in a ball mill jar, using agate as the milling medium and deionized water as the dispersion medium, and subjected to liquid-phase assisted three-dimensional vibration wet ball milling for 8.5 hours. The wet-milled slurry was then dried at 95℃; subsequently, it was removed, placed in an agate mortar, and manually ground for 1.5 hours to obtain the precursor powder.

[0063] b. After calcining the precursor powder obtained in step a at 1100℃ for 3 hours, it is then manually ground for 2 hours to obtain chromate powder.

[0064] c. The chromate powder obtained in step b is pressed using a single-shaft hydraulic press at 16 kg / cm³. 2 Dry pressing was performed under pressure for 4 minutes to obtain a dry-pressed block. The dry-pressed block was then subjected to cold isostatic pressing at 280 MPa for 10 minutes to obtain a cold isostatically pressed block. The cold isostatically pressed block was then sintered at 1550℃ for 10.5 hours to obtain a high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor ceramic material (La). 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 CrO3.

[0065] The obtained high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor ceramic material (La) 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6Gd 1 / 6 Ho 1 / 6 The electrical properties of CrO3 were tested, and the relationship between resistivity and temperature was as follows: Figure 2 As shown, the electrical parameters of this material are B. 25℃ / 1500℃ =1950 K, ρ 1500℃ =1.44×10 2 Ω·cm. Meanwhile, the prepared (La) 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Ho 1 / 6 The relationship between the resistivity drift rate of CrO3 ceramic material at 1500 ℃ and aging time was determined, and the test results are as follows: Figure 6 As shown.

[0066] Example 3

[0067] In this embodiment, the preparation process of high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6Eu 1 / 6 Gd 1 / 6 Y 1 / 6 )CrO3 is as follows.

[0068] a. According to the molar ratio of La:Nd:Sm:Eu:Gd:Y:Cr=1:1:1:1:1:1:6, oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, yttrium trioxide and chromium trioxide are respectively weighed and mixed to obtain an initial mixture. The initial mixture is placed in a ball mill tank, agate is used as the ball milling medium, and deionized water is used as the dispersion medium. After liquid phase assisted three-dimensional vibration wet ball milling for 9 hours, the wet milled slurry is dried at a temperature of 100℃. Then, it is taken out and placed in an agate mortar for manual grinding for 1.5 hours to obtain a precursor powder.

[0069] b. The precursor powder obtained in step a is calcined at 1200℃ for 4 hours, and then manually ground for 4 hours to obtain a chromate powder.

[0070] c. The chromate powder obtained in step b is dry-pressed into a block by a single-shaft oil press under a pressure of 17 kg / cm 2 for 7 minutes to obtain a dry-pressed block. The dry-pressed block is cold isostatic pressed at a pressure of 290 MPa for 15 minutes to obtain a cold isostatic pressed block. The cold isostatic pressed block is sintered at a temperature of 1580℃ for 11 hours to obtain a high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 )CrO3.

[0071] The obtained high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6Gd 1 / 6 Y 1 / 6 )CrO3 is subjected to electrical performance test. The relationship between resistivity and temperature is shown in Figure 3 . The electrical parameters of the material are B 25℃ / 1500℃ =1969 K, and p 1500℃ =1.51×10 2 Ω·cm. At the same time, the prepared (La1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 The resistance drift rate of the CrO3 ceramic material at 1500℃ and the aging time were determined, and the test results are shown in Table 1. Figure 7

[0072] Example 4

[0073] In this embodiment, the preparation process of the high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6Eu 1 / 6 Gd 1 / 6 Er 1 / 6 )CrO3 is as follows.

[0074] a. According to the molar ratio of La:Nd:Sm:Eu:Gd:Er:Cr=1:1:1:1:1:1:6, oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, erbium trioxide and chromium trioxide were respectively weighed and mixed to obtain an initial mixture. The initial mixture was placed in a ball mill tank, agate was used as the ball milling medium, and deionized water was used as the dispersion medium. Liquid phase assisted three-dimensional vibration wet ball milling was carried out for 10 hours. Then, the wet milled slurry was dried at a temperature of 120℃. After that, it was taken out and placed in an agate mortar for manual grinding for 3 hours to obtain a precursor powder.

[0075] b. The precursor powder obtained in step a was calcined at 1300℃ for 5 hours, and then manually ground for 5 hours to obtain a chromate powder.

[0076] c. The chromate powder obtained in step b was dry-pressed into a block by a single-shaft oil press at a pressure of 18kg / cm 2 for 10 minutes to obtain a dry-pressed block. The dry-pressed block was cold isostatic pressed at a pressure of 300MPa for 20 minutes to obtain a cold isostatic pressed block. The cold isostatic pressed block was sintered at a temperature of 1600℃ for 12 hours to obtain the high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Er 1 / 6 )CrO3.

[0077] The obtained high-entropy rare earth chromate high-temperature type negative temperature coefficient thermosensitive ceramic material (La 1 / 6 Nd 1 / 6 Sm​1 / 6 Eu 1 / 6Gd 1 / 6 Er 1 / 6 The electrical properties of CrO3 were tested, and the relationship between resistivity and temperature was as follows: Figure 4 As shown, the electrical parameters of this material are B. 25℃ / 1500℃ =2011 K, ρ 1500℃ =1.60×10 2 Ω·cm. Meanwhile, the prepared (La) 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Er 1 / 6 The relationship between the resistivity drift rate of CrO3 ceramic material at 1500 ℃ and aging time was determined, and the test results are as follows: Figure 8 As shown.

[0078] Figure 9 For (La) 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 CrO3 ceramic materials, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6Ho 1 / 6 CrO3 ceramic materials, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 Y 1 / 6 CrO3 ceramic materials, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6Er 1 / 6 A summary graph of the resistivity versus temperature relationship of CrO3 ceramic materials.

[0079] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

[0080] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0081] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0082] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although some inventive embodiments that are currently considered useful have been discussed by way of various examples in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

[0083] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0084] For each patent, patent application, patent application publication, and other material such as articles, books, specifications, publications, and documents referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0085] Finally, it should be understood that the embodiments described herein are only given by way of example and that other modifications can occur to persons skilled in the art. Therefore, the scope of the present description is not intended to be limited to the embodiments described herein but is only limited by the claims that follow.

Claims

1. A high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material, characterized in that, (La 1 / 6 Nd 1 / 6Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3, where M is Dy, Ho, Y or Er; The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has a negative temperature coefficient characteristic in a range of 25-1500 DEG C. The electrical performance parameters of the high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material are as follows: B 25℃ / 1500℃ =1927~2011K, p 1500℃ =1.29×10 2 ~1.60×10 2 Ω·cm; The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material has an electrical resistance drift rate of less than 4.6% after aging for 500 hours at 1500 DEG C.

2. The preparation method of the high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material according to claim 1, characterized in that, The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is prepared by mixing and sintering raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, chromium trioxide and an oxide of M in a molar ratio according to a chemical formula; in the oxide of M, M is Dy, Ho, Y or Er.

3. The production method according to claim 1 or 2, characterized by, The method comprises the following steps: a. According to a substance amount ratio of La:Nd:Sm:Eu:Gd:M:Cr=1:1:1:1:1:1:6, lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, gadolinium trioxide, an oxide of M and chromium trioxide are respectively taken and mixed to obtain an initial mixture; the initial mixture is ground to obtain a precursor powder; M is Dy, Ho, Y or Er, and the oxide of M is dysprosium trioxide, holmium trioxide, yttrium trioxide or erbium trioxide; b. The precursor powder obtained in step a is calcined and ground to obtain a chromate powder; c. The chromate powder obtained in step b is dry-pressed to obtain a dry-pressed block; the dry-pressed block is cold isostatic pressed to obtain a cold isostatic pressed block; and the cold isostatic pressed block is sintered to obtain the high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material.

4. The production method according to claim 3, characterized by, In step a, the initial mixture is wet ball-milled, dried, and then ground to obtain the precursor powder.

5. The preparation method according to claim 3, characterized in that, In step b, the calcination temperature is 900 DEG C.-1300 DEG C., and the calcination time is 2-5 hours; after calcination, the powder is ground to obtain the chromate powder.

6. The preparation method according to claim 3, characterized in that, In step c, the sintering temperature is 1500 DEG C.-1600 DEG C., and the sintering time is 10-12 hours.

7. The use of the high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material prepared by the method according to any one of claims 1-6, characterized in that, (La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 Gd 1 / 6 M 1 / 6 )CrO3, where M is Dy, Ho, Y or Er.

8. Use according to claim 7, characterized in that, The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is used to prepare a high-temperature thermosensitive sensor.

9. Use according to claim 7, characterized in that, The high-entropy rare earth chromate negative temperature coefficient thermosensitive ceramic material is used to prepare a negative temperature coefficient thermosensitive sensor.

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