High-entropy perovskite high-temperature negative temperature coefficient thermosensitive ceramic, preparation method and application

Abstract

This invention provides a high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic, its preparation method, and its application, belonging to the field of perovskite semiconductor materials. This series of high-temperature negative temperature coefficient thermistors involves mixing lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, and chromium trioxide with oxides of lanthanum oxide (La), followed by wet three-dimensional vibration ball milling, powder calcination, cold isostatic pressing, and high-temperature sintering to obtain a perovskite structure (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3 thermistor material, where A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y. The electrical performance parameters of the series of materials prepared in the examples were determined as follows: B 25℃ / 1500℃ =1625K~1742K, ρ 1500℃ =7.48×10 2 Ω·cm~7.75×10 2 The material exhibits excellent negative temperature coefficient characteristics within the temperature range of 25℃ to 1500℃ and demonstrates high-temperature aging stability. The high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic of this application has an upper limit of applicable temperature up to 1500℃, high resistance-temperature linear correlation, and good consistency, making it suitable for manufacturing high-temperature thermistor components.

Description

Technical Field

[0001] This invention relates to the field of materials, particularly to the field of perovskite semiconductor materials, specifically to a high-entropy perovskite high-temperature negative temperature coefficient thermistor ceramic, its preparation method, and its application (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3 (A = Pr, Tb, Dy, Ho, Er, Yb, Lu, Y). More specifically, it provides a high-temperature negative temperature coefficient thermistor based on high-entropy rare earth chromates, a method for preparing the ceramic, and its application as a semiconductor material. Background Technology

[0002] Sensor technology is a cutting-edge technology in modern science and technology, and one of the three pillars of modern information technology. Its level is an important indicator of a country's technological development. Sensitive components and sensors are basic products in the electronic information manufacturing industry, and are special components among the new electronic components that will be the focus of development during the "15th Five-Year Plan" and the next 12-20 years.

[0003] Temperature, as one of the most fundamental thermodynamic physical parameters, is crucial for measurement and control in scientific research, industrial production, and daily life. In recent years, with my country's rapid development and breakthroughs in various fields such as the Internet of Things, big data, cloud computing, and smart cities, the demand for sensor technology will be enormous.

[0004] In the field of semiconductor device technology, negative temperature coefficient (NTC) thermistors exhibit an exponential decrease in resistance with increasing temperature. Due to their advantages such as low cost, fast response, and high measurement accuracy, NTC thermistors are widely used in temperature measurement, temperature control, temperature compensation, and surge current suppression. The material constant B of an NTC thermistor characterizes its temperature sensitivity; a larger B value indicates a greater rate of change in resistance with temperature, and thus better temperature sensitivity. Common thermistor ceramic materials are made from various transition metal oxides such as Mn, Fe, Co, and Ni, doped with some rare earth metal oxides, using traditional semiconductor ceramic processes. By selecting different material systems, adjusting the formulation ratios, and modifying the preparation process (sintering atmosphere, pre-firing temperature, sintering temperature, holding time, etc.), NTC thermistor materials with different resistivities and B values ​​can be obtained, thus producing thermistor devices that meet various needs. With the rapid development of technology and the trend towards integration and intelligence in electronic devices, the commonly used spinel-type thermistor ceramic resistors can no longer fully meet the needs of practical applications. Therefore, there is an urgent need to develop new thermistors that are suitable for higher temperatures, higher precision, and wide temperature range applications. Perovskite-structured NTC thermistor materials have attracted considerable attention due to their adaptability at high temperatures. How to further improve the performance of perovskite-type NTC thermistors has become a hot research topic. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy perovskite-type high-temperature negative temperature coefficient thermistor, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] High-entropy perovskite-type high-temperature negative temperature coefficient thermistors, with the chemical formula (La... 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3, wherein A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y.

[0008] This negative temperature coefficient thermistor is made by mixing and firing raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, and chromium trioxide with oxides of A.

[0009] The oxide of A is an oxide of Pr, Tb, Dy, Ho, Er, Yb, Lu, or Y.

[0010] Where A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y.

[0011] The oxide of A is praseodymium trioxide, terbium trioxide, dysprosium trioxide, holmium trioxide, erbium trioxide, ytterbium trioxide, lutetium trioxide, and yttrium trioxide.

[0012] This series of negative temperature coefficient thermistors is made by mixing and firing raw materials lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, and chromium trioxide with praseodymium trioxide, terbium trioxide, dysprosium trioxide, holmium trioxide, erbium trioxide, ytterbium trioxide, lutetium trioxide, and yttrium trioxide in the molar ratio of their chemical formulas.

[0013] The electrical performance parameters of this high-entropy perovskite-type high-temperature negative temperature coefficient thermistor are as follows: B 25℃ / 1500℃ =1625K~1742K, ρ 1500℃ =7.48×10 2 Ω·cm~7.75×10 2 Ω·cm, applicable temperature range is 25℃~1500℃.

[0014] The aforementioned method for preparing high-entropy perovskite-type high-temperature negative temperature coefficient thermistors includes the following steps:

[0015] a. According to the molar ratio of La:Nd:Sm:Eu:A:Cr=1:1:1:1:1:5, weigh out the oxide powders of lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, oxide of A and chromium trioxide respectively, and mix them to obtain an initial mixture; after wet three-dimensional vibration ball milling of the initial mixture for 8 to 11 hours, dry the wet milled slurry, take it out and place it in an agate mortar and grind it manually for 1 to 5 hours to obtain the precursor powder;

[0016] b. After calcining the precursor powder obtained in step a at 1100℃ for 3 to 20 hours, it is then manually ground for 0.5 to 10 hours to obtain perovskite phase powder.

[0017] c. Press the perovskite phase powder obtained in step b into blocks using a single-axis hydraulic press to obtain a second shaped block; after cold isostatic pressing of the second shaped block, a third isostatic pressing block is obtained; sinter the third isostatic pressing block at 1600℃ for 15 to 20 hours to obtain a high-entropy rare earth chromate high-temperature negative temperature coefficient thermistor material.

[0018] In step a, the wet-milled slurry is dried at a temperature of 100℃ to 150℃. Further, the drying temperature is 100℃.

[0019] In step a, according to the molar ratio of La:Nd:Sm:Eu:A:Cr=1:1:1:1:1:5, the oxide powders of lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, oxides of A, and chromium trioxide are weighed and mixed, placed in a ball mill jar, and wet three-dimensional vibration ball milling is performed for 8 to 11 hours using agate as the ball milling medium and analytical grade anhydrous ethanol as the dispersion medium. The wet-milled slurry is dried at a temperature of 100℃ to 150℃, taken out and placed in an agate mortar for manual grinding for 2 to 5 hours to obtain the precursor powder.

[0020] In step b, the precursor powder obtained in step a is calcined at 1100°C for 5 to 10 hours, and then manually ground for 2 hours to obtain the perovskite phase (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3 (A=Pr, Tb, Dy, Ho, Er, Yb, Lu, Y) powder.

[0021] In step c, the perovskite phase powder obtained in step b is processed using a single-shaft hydraulic press at a pressure of 15–20 kg / cm³. 2 The material is pressed into blocks under pressure for 2 minutes to obtain a second block; the second block is then subjected to cold isostatic pressing at a pressure of 250MPa to 300MPa for 3 minutes to obtain a third isostatically pressed block; the third isostatically pressed block is then sintered at 1600℃ for 15 to 20 hours to obtain a high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3 (A=Pr, Tb, Dy, Ho, Er, Yb, Lu, Y).

[0022] A is one of Dy, Ho, and Er; its chemical formula is (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 CrO3 (A = Dy, Ho, Er).

[0023] The aforementioned applications of high-entropy perovskite-type high-temperature negative temperature coefficient thermistors.

[0024] This high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic is used in the field of semiconductor sensors. The chemical formula of the high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic is (La... 0.2 Nd 0.2 Sm0.2 Eu 0.2 A 0.2 )CrO3, where A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y.

[0025] This high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic was used as a high-temperature negative temperature coefficient thermistor material.

[0026] Currently, research on high-temperature NTC materials mainly focuses on chromium-based perovskites and their composite structures. While these materials have a wide operating temperature range (25℃~900℃) and tunable electrical properties, they are prone to elemental volatilization at high temperatures. This not only makes it difficult to sinter the materials into a dense, uniform structure in air, but also triggers side reactions at grain boundaries and the precipitation of second phases. This leads to the dispersion and continuous variation of the thermistor's resistance at high temperatures, thus reducing its high-temperature aging stability and the feasibility of large-scale production. Regarding perovskite composites with high-resistivity oxide phases and low-resistivity phases, although electrical theory predicts they can be used for NTC materials with a wide temperature range and a high upper temperature limit, actual research shows that two-phase percolation and ion migration at high temperatures cause changes in their internal electrical properties, resulting in unstable resistance. Therefore, traditional perovskites and their composites can no longer meet the increasingly stringent technical standards for high-temperature NTC materials.

[0027] Therefore, improving the high-temperature stability of perovskite structures has become an urgent problem to be solved. To this end, this application provides a high-entropy perovskite-type high-temperature negative temperature coefficient thermistor, its preparation method, and its application.

[0028] The chemical formula of this high-entropy perovskite-type high-temperature negative temperature coefficient thermistor is (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 CrO3, where A is one of praseodymium (Pr), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb), lutetium (Lu), and yttrium (Y). This thermistor ceramic employs a high-entropy, multi-component design, exhibiting a significant negative temperature coefficient and a wide testing temperature range. The upper limit of the detection temperature of the prepared NTC ceramic is effectively improved, and it demonstrates excellent aging stability. The high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic of this application exhibits stable electrical properties, high linear correlation, and good consistency, making it suitable for manufacturing thermistor devices.

[0029] As shown in the following example, when A = Dy, Ho, Er, the obtained (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2The electrical properties of CrO3 are as follows: B 25℃ / 1500℃ =1625K~1742K, ρ 1500℃ =7.48×10 2 Ω·cm~7.75×10 2 The thermistor material exhibits a significant negative temperature coefficient within the temperature range of 25℃ to 1500℃, with a high upper limit for temperature measurement and good consistency in electrical performance. After aging at 1500℃ for 500 hours, its resistivity drift rate is less than 5%, demonstrating stable high-temperature electrical performance and high sensitivity. Therefore, the high-entropy rare-earth chromate of this invention is suitable for manufacturing high-temperature negative temperature coefficient thermistors with excellent stability. Attached Figure Description

[0030] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0031] Figure 1 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 XRD (X-ray diffraction) pattern of CrO3 material.

[0032] Figure 2 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Ho 0.2 XRD (X-ray diffraction) pattern of CrO3 material.

[0033] Figure 3 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 XRD (X-ray diffraction) pattern of CrO3 material.

[0034] Figure 4 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 The relationship between resistivity and temperature of CrO3 material.

[0035] Figure 5 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Ho 0.2 The relationship between resistivity and temperature of CrO3 material.

[0036] Figure 6 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 The relationship between resistivity and temperature of CrO3 material.

[0037] Figure 7 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 The relationship between the resistance drift rate of CrO3 material at 1500℃ and aging time.

[0038] Figure 8 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Ho 0.2 The relationship between the resistance drift rate of CrO3 material at 1500℃ and aging time.

[0039] Figure 9 For the present invention (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 The relationship between the resistance drift rate of CrO3 material at 1500℃ and aging time. Detailed Implementation

[0040] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0041] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0042] Example 1

[0043] a. According to the molar ratio of La:Nd:Sm:Eu:Dy:Cr=1:1:1:1:1:5, weigh out the oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, dysprosium trioxide and chromium trioxide respectively and mix them to obtain an initial mixture; after wet three-dimensional vibration ball milling of the initial mixture for 8 hours, dry the wet milled slurry at 100℃, take it out and place it in an agate mortar and grind it manually for 2 hours to obtain the precursor powder.

[0044] b. After calcining the precursor powder obtained in step a at 1100℃ for 5 hours, it is then manually ground for 2 hours to obtain perovskite phase powder.

[0045] c. The perovskite phase powder obtained in step b is pressed using a single-shaft hydraulic press at 15 kg·cm³. -2 The material is pressed into blocks under pressure for 2 minutes to obtain a second block; the second block is then subjected to cold isostatic pressing at 250 MPa for 3 minutes to obtain a third isostatically pressed block; the third isostatically pressed block is then sintered at 1600℃ for 15 hours to obtain a high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 CrO3. XRD analysis was performed on the prepared ceramic sheets, and the results are as follows: Figure 1 As shown.

[0046] The obtained (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 Electrical performance tests were conducted on CrO3 negative temperature coefficient thermistor ceramic materials. The relationship between resistivity and temperature is as follows: Figure 4 The obtained electrical parameter is B. 25℃ / 1500℃ =1625K, ρ 1500℃ =7.48×10 2 Ω·cm. Meanwhile, the prepared (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Dy 0.2 The relationship between the resistivity drift rate of CrO3 material at 1500℃ and aging time was determined, and the results were obtained. Figure 7 .

[0047] Example 2

[0048] a. According to the molar ratio of La:Nd:Sm:Eu:Ho:Cr=1:1:1:1:1:5, weigh out the oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, holmium trioxide and chromium trioxide respectively and mix them to obtain an initial mixture; after wet three-dimensional vibration ball milling of the initial mixture for 9 hours, dry the wet milled slurry at 120℃, take it out and place it in an agate mortar and grind it manually for 4 hours to obtain the precursor powder.

[0049] b. After calcining the precursor powder obtained in step a at 1100℃ for 8 hours, it is then manually ground for 2 hours to obtain perovskite phase powder.

[0050] c. The perovskite phase powder obtained in step b is pressed using a single-shaft hydraulic press at 18 kg·cm³. -2 The material is pressed into blocks under pressure for 2 minutes to obtain a second block; the second block is then subjected to cold isostatic pressing at 280 MPa for 3 minutes to obtain a third isostatically pressed block; the third isostatically pressed block is then sintered at 1600℃ for 18 hours to obtain a high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Ho 0.2 CrO3. XRD analysis was performed on the prepared ceramic sheets, and the results are as follows: Figure 2 As shown.

[0051] The obtained (La) 0.2 Nd 0.2 Sm0 .2 Eu 0.2 Ho 0.2 Electrical performance tests were conducted on CrO3 negative temperature coefficient thermistor ceramic materials. The relationship between resistivity and temperature is as follows: Figure 5 The obtained electrical parameter is B. 25℃ / 1500℃ =1682K, ρ 1500℃ =7.61×10 2 Ω·cm. Meanwhile, the prepared (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Ho 0.2 The relationship between the resistivity drift rate of CrO3 material at 1500℃ and aging time was determined, and the results were obtained. Figure 8 .

[0052] Example 3

[0053] a. According to the molar ratio of La:Nd:Sm:Eu:Er:Cr=1:1:1:1:1:5, weigh out the oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, erbium trioxide and chromium trioxide respectively and mix them to obtain an initial mixture; after wet three-dimensional vibration ball milling of the initial mixture for 10 hours, dry the wet milled slurry at 140℃, take it out and place it in an agate mortar and grind it manually for 5 hours to obtain the precursor powder.

[0054] b. After calcining the precursor powder obtained in step a at 1100℃ for 10 hours, it is then manually ground for 2 hours to obtain perovskite phase powder.

[0055] c. The perovskite phase powder obtained in step b is pressed using a single-shaft hydraulic press at 20 kg·cm³. -2 The material is pressed into blocks under pressure for 2 minutes to obtain a second block; the second block is then subjected to cold isostatic pressing at 250 MPa for 3 minutes to obtain a third isostatically pressed block; the third isostatically pressed block is then sintered at 1600℃ for 20 hours to obtain a high-entropy rare-earth chromate high-temperature negative temperature coefficient thermistor (La). 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 CrO3. XRD analysis was performed on the prepared ceramic sheets, and the results are as follows: Figure 3 As shown.

[0056] The obtained (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 Electrical performance tests were conducted on CrO3 negative temperature coefficient thermistor ceramic materials. The relationship between resistivity and temperature is as follows: Figure 6 The obtained electrical parameter is B. 25℃ / 1500℃ =1719K, ρ 1500℃ =7.75×10 2 Ω·cm. Meanwhile, the prepared (La) 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Er 0.2 The relationship between the resistivity drift rate of CrO3 material at 1500℃ and aging time was determined, and the results were obtained. Figure 9 .

[0057] The thermosensitive material (La) prepared in the above embodiments 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 CrO3 (A = Dy, Ho, Er) exhibits NTC characteristics in a temperature range of 25-1500℃, with a wide test temperature range and an upper limit of 1500℃. After aging at 1500℃ for 500 hours, the resistance drift rate is less than 5%, demonstrating excellent high-temperature aging stability. This thermistor material has high resistivity in high-temperature environments, ensuring the accuracy of its measurements.

[0058] 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.

Claims

1. A high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic, characterized in that, Its chemical formula is (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3, wherein A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y; The electrical performance parameters of this high-entropy perovskite-type high-temperature negative temperature coefficient thermistor are as follows: B 25℃ / 1500℃ =1625~1742 K, ρ 1500℃ =7.48~7.75×10 2 Ω·cm, applicable temperature range is 25-1500℃; This high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic is prepared by a method including the following steps: a. Weigh out the oxide powders lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, oxide of A, and chromium trioxide according to the molar ratio of La:Nd:Sm:Eu:A:Cr=1:1:1:1:1:5 and mix them to obtain an initial mixture; after wet three-dimensional vibration ball milling the initial mixture for 8-11 hours, dry the wet-milled slurry, take it out and place it in an agate mortar and grind it manually for 1-5 hours to obtain the precursor powder; b. After calcining the precursor powder obtained in step a at 1100℃ for 3 to 20 hours, it is then manually ground for 0.5 to 10 hours to obtain perovskite phase powder. c. Press the perovskite phase powder obtained in step b into blocks using a single-shaft hydraulic press to obtain a second shaped block. After the second molding block is cold isostatically pressed, a third isostatically pressed block is obtained; the third isostatically pressed block is sintered at 1600℃ for 15~20h to obtain a high-entropy rare earth chromate high-temperature negative temperature coefficient thermistor material.

2. The high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic according to claim 1, characterized in that, In step a, according to the molar ratio of La:Nd:Sm:Eu:A:Cr=1:1:1:1:1:5, the oxide powders of lanthanum trioxide, neodymium trioxide, samarium trioxide, europium trioxide, oxides of A, and chromium trioxide are weighed and mixed, placed in a ball mill jar, and wet three-dimensional vibration ball milling is performed for 8-11 hours using agate as the ball milling medium and analytical grade anhydrous ethanol as the dispersion medium. The wet-milled slurry is dried at a temperature of 100-150℃, taken out and placed in an agate mortar for manual grinding for 2-5 hours to obtain the precursor powder.

3. The high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic according to claim 1, characterized in that, In step b, the precursor powder obtained in step a is calcined at 1100℃ for 5-10 hours, and then manually ground for 2 hours to obtain perovskite phase powder.

4. Application of the high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic described in any one of claims 1 to 3.

5. The application according to claim 4, characterized in that, This high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic is used in the field of semiconductor sensors. The chemical formula of the high-entropy perovskite-type high-temperature negative temperature coefficient thermistor ceramic is (La... 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3, where A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, and Y.

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