Perovskite thermistor material, preparation method and application thereof

Abstract

The application discloses a perovskite thermistor material, a preparation method and application thereof. The perovskite thermistor material is prepared from barium carbonate, bismuth oxide, lead oxide, sodium carbonate and potassium carbonate as raw materials by a solid phase reaction method, and has a chemical formula of (Ba 1‑y Re y )(Bi 1‑x R x )O3. In the formula, Re=Pb, 0≤y≤0.1; R=Na, K, 0≤x≤0.15. The perovskite thermistor material has a single perovskite structure. The material can be sintered into a porcelain at a low temperature, and the oxygen vacancies can be effectively adjusted under different sintering atmospheres, so that the material constant and the resistivity of the thermistor ceramic can be significantly reduced, and the perovskite thermistor material can be used for measurement and control in a temperature range of 40-160K at a low temperature.

Description

Technical Field

[0001] This invention belongs to the field of thermistor materials, and relates to a perovskite thermistor material, its preparation method and its application, especially a perovskite phase negative temperature coefficient thermistor material suitable for low temperature, its preparation method and its application. Background Technology

[0002] The development of cryogenic physics and space technology has placed higher demands on the temperature monitoring and control of negative temperature coefficient (NTC) thermistors in extremely low-temperature environments. For environments requiring cryogenic temperature detection, the resistance value of NTC thermistors cannot exceed a certain allowable value. As the temperature decreases, materials with a lower thermistor constant (B) must be selected. To reduce the B value, spinel Mn-Co-Ni-O thermistors often incorporate elements with good electrical conductivity, such as Cu, but this leads to severe aging phenomena.

[0003] Researchers developed SrCo 1-x Ni x O 3-δ and perovskite La 1-x Ce x BaCo2O5 low-temperature materials are controversial due to their resistivity shift at low temperatures, with the core challenge being the resistivity drift caused by oxygen vacancy accumulation at grain boundaries. Recently, perovskite high-temperature superconducting materials such as BaPbBiO3 (T...) have also gained attention. c ~12 K) and BaKBiO3(T c The cryogenic potential of ~34 K (BBO) has been explored. The substitution of B sites by low-valence elements creates oxygen vacancies. However, the oxygen vacancy control caused by doping is insufficient, and resistance drift is also a challenge for thermosensitive materials.

[0004] Based on the above analysis, oxygen vacancies are highly flexible and can be used to control the influence of oxygen ions on surrounding ions, thereby achieving the goal of extremely low temperatures. Doping with ions of different radii and valence states can adjust the room temperature resistivity and material constant of the material. First, adjusting the sintering atmosphere, sintering under high-purity argon gas increases the number of oxygen vacancies, causing the temperature measurement range to shift towards extremely low temperatures. Second, Na / K doping can control the radius and valence state at the B site: Na + / K + Compare 3+ Due to significant differences in valence states, doping introduces donor levels, increases carrier concentration, and reduces the jumping energy barrier, thereby optimizing electrical properties across different temperature ranges. Pb exhibits Ba... 2+ The same valence state (Pb) 2+ Furthermore, the ionic radii are similar, and Ba at the A site is substituted. 2+ This can improve the stability of the material. Finally, the introduction of sodium, potassium, and lead oxides can significantly reduce the sintering temperature, acting as sintering aids, saving energy and improving sintering efficiency.

[0005] Therefore, there is an urgent need to develop a thermistor material with low resistivity at low temperatures, whose abundant oxygen vacancies provide conductive channels, thereby further reducing resistivity. Modification by doping with different elements can optimize the material's resistivity and improve the stability of the thermistor, thus achieving a synergistic improvement in both resistivity and stability. Summary of the Invention

[0006] In view of this, the present invention provides a perovskite (chemical formula ABO3) thermistor material with a negative temperature coefficient, its preparation method, and its application. It provides a method that can effectively regulate oxygen vacancy concentration while reducing the resistivity and aging mobility of the thermistor material at extremely low temperatures. The present invention controls the oxygen vacancy concentration by changing the sintering atmosphere, featuring an adjustable preparation process; it introduces a B-site variable valence charge element to effectively regulate carrier concentration and potential barrier, thereby controlling resistivity. The introduction of an A-site element improves stability. Furthermore, the introduced element can act as a sintering aid, significantly reducing the sintering temperature. This material is a low thermistor constant material, suitable for extremely low temperature measurement and control and alarm, and possesses excellent stability, overcoming the core problems of existing thermistor elements such as high resistance and poor controllability at extremely low temperatures.

[0007] To achieve the above objectives, the present invention mainly provides the following technical solutions: This invention provides a perovskite thermistor material, which is a perovskite phase ceramic material with the chemical formula (Ba). 1-y Re y (Bi) 1-x R x O3; x is 0 or y is 0; When x is 0, Re is Pb, and 0 ≤ y ≤ 0.1; When y is 0, R is Na or K, and 0 ≤ x ≤ 0.15.

[0008] In some preferred embodiments, the above-mentioned perovskite thermistor material is prepared by the following steps: 1) Weigh the raw materials according to the proportions. The molar ratio of each raw material, calculated by metal element, is as follows: When x is 0, the molar ratio of barium carbonate, lead oxide, and bismuth oxide is 0.9-1 : 0.0-0.1 : 1. When y is 0, the molar ratio of barium carbonate, bismuth oxide, sodium carbonate, or potassium carbonate is 1 : 0.85-1 : 0-0.15; 2) Add barium carbonate, bismuth oxide, and one of lead oxide, sodium carbonate, and potassium carbonate in sequence, and mix for 1-3 hours; 3) Place the mixture obtained in step 2) into a polytetrafluoroethylene container, add agate balls, dispersant and binder, and ball mill to obtain a mixed powder; 4) The mixed powder was calcined in air to obtain (Ba 1-y Re y (Bi) 1-x R x O3 calcined materials; 5) The calcined (Ba) 1-y Re y (Bi) 1-x R x The calcined material was added to an agate mortar and ground to obtain (Ba 1-y Re y (Bi) 1-x R x O3 powder; then (Ba 1-y Re y (Bi) 1-x R x O3 powder briquettes; 6) After pressing (Ba) 1-y Re y (Bi) 1-x R x O3 blocks were placed in buried sintering powder and sintered under an atmosphere to obtain the chemical formula (Ba). 1-y Re y (Bi) 1-x R x The perovskite thermistor material of O3.

[0009] The final chemical formula obtained is (Ba 1-y Re y (Bi) 1-x R x The negative temperature coefficient thermistor material of O3 is a ceramic material with a single perovskite structure. By adjusting the sintering atmosphere or doping with other elements, the material constant, resistivity, and anti-aging properties of the thermistor ceramic can be significantly adjusted.

[0010] Preferably, the mass ratio of the mixture, agate balls, and dispersant is 1:1:4; the mass of the binder is 3%-5% of the mass of the mixture; and the ball milling time is 18-20 hours. The binder is PVB.

[0011] Preferably, the dispersant is a mixture of anhydrous ethanol and glycerol; wherein the volume ratio of anhydrous ethanol to glycerol is (1~9):(1~9).

[0012] Preferably, the calcination temperature in step 4) is 650-750℃ and the calcination time is 2-6h.

[0013] Preferably, the pressing block in step 5) includes the following steps: The (Ba)1-y Re y (Bi) 1-x R x O3 powder is uniaxially compressed into blocks at a pressure of 2-4 MPa for 30-90 seconds.

[0014] Preferably, the pressing block in step 5) further includes cold isostatic pressing at a pressure of 280MPa for 350-380s to obtain a Ф25×1.8mm block.

[0015] Preferably, the sintering temperature in step 6) is 700℃-850℃, the sintering time is 3-5h, and the sintering atmosphere is high-purity argon.

[0016] Preferably, the calcined powder in step 6) is zirconium oxide powder.

[0017] In another aspect, the present invention also provides the application of any of the above-mentioned perovskite thermistor materials for temperature measurement and control, particularly for temperature measurement and control at extremely low temperatures of 40-160K.

[0018] Compared with the prior art, the present invention has the following technical effects: 1. The present invention (Ba 1-y Re y (Bi) 1-x R x In O3 materials, adjusting the sintering atmosphere and sintering under high-purity argon increases the number of oxygen vacancies, causing the temperature measurement range to shift to extremely low temperatures.

[0019] 2. The present invention (Ba 1-y Re y (Bi) 1-x R x In O3 materials, Pb at the A site 2+ relatively 2+ The valence state and ionic radius are similar, which enhances the stability of the structure and improves the anti-aging properties of the material.

[0020] 3. The present invention (Ba 1-y Re y (Bi) 1-x R x In O3 materials, the B site contains Na + / K + Compare 3+Due to significant differences in valence states, doping introduces donor levels, increases carrier concentration, and reduces jumping energy barriers, thereby optimizing electrical characteristics in different temperature ranges. The zirconia powder used in this invention has a melting point of approximately 2500℃. This powder does not exhibit volatility at sintering temperatures of 750℃-900℃, and it also possesses a low coefficient of thermal expansion and high thermal conductivity, enabling the NTC thermistor material to be uniformly heated within the powder.

[0021] 4. Thermistors can be used to measure and control temperature ranges from 40 to 160 K. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation process of Example 1 of the present invention; Figure 2 A (Ba) provided in Embodiment 1 of the present invention 1-y Re y (Bi) 1-x R x X-ray diffraction pattern of O3 negative temperature coefficient thermistor material; Figure 3 A (Ba) provided in Embodiment 1 of the present invention 1-y Re y (Bi) 1-x R x Scanning electron microscope image of O3 negative temperature coefficient thermistor ceramic; Figure 4 A (Ba) provided in Embodiment 1 of the present invention 1-y Re y (Bi) 1-x R x X-ray diffraction pattern of O3 negative temperature coefficient thermistor ceramic; Figure 5 The embodiments and comparative examples provided by this invention yielded (Ba) 1-y Re y (Bi) 1-x R x Aging resistance deviation rate diagram of O3 negative temperature coefficient thermistor ceramic; Figure 6 The embodiments and comparative examples provided by this invention yielded (Ba) 1-y Re y (Bi) 1-x R x O3 negative temperature coefficient thermistor ceramics A graph showing the relationship between 1 / T; Figure 7 The (Ba) prepared for Comparative Example 2 provided by the present invention 1-y Re y (Bi) 1-x R xX-ray diffraction pattern of O3 ultra-low temperature thermistor ceramic. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] On one hand, embodiments of the present invention provide a thermistor material, which is a perovskite-phase ceramic material with the chemical formula (Ba). 1-y Re y (Bi) 1-x R x O3; x is 0 or y is 0; When x is 0, Re is Pb, and 0 ≤ y ≤ 0.1; When y is 0, R is Na or K, and 0 ≤ x ≤ 0.15.

[0025] The molar ratio of each raw material, calculated by metallic element, is as follows: When x is 0, the molar ratio of barium carbonate, lead oxide, and bismuth oxide is 0.9-1 : 0.0-0.1 : 1. When y is 0, the molar ratio of barium carbonate, bismuth oxide, sodium carbonate, or potassium carbonate is 1 : 0.85-1 : 0-0.15; The present invention (Ba 1-y Re y (Bi) 1-x R x In O3 negative temperature coefficient thermistor materials (BBPO / BBNO / BBKO for short), adjusting the sintering atmosphere and sintering under high-purity argon increases the number of oxygen vacancies, causing the temperature measurement range to shift to extremely low temperatures. A-site Pb 2+ relatively 2+ The similarity between valence state and ionic radius enhances structural stability and improves the material's anti-aging properties. Na + / K + Compare 3+ Due to the significant difference in valence states, doping introduces donor levels, increases carrier concentration, and reduces the jumping energy barrier, thereby optimizing the electrical characteristics in different temperature ranges.

[0026] On the other hand, embodiments of the present invention also provide a method for preparing a thermistor material, comprising the following steps: To prepare mixtures of various oxides; The mixture was placed in a polytetrafluoroethylene container, and agate balls and dispersant were added for ball milling to obtain a mixed powder. The mixed powder was calcined in air to obtain (Ba 1-y Re y (Bi) 1-x R x O3 calcined materials; calcined (Ba 1-y Re y (Bi) 1-x R x The calcined material was added to an agate mortar and ground to obtain (Ba 1- y Re y (Bi) 1-x R x )O3 powder.

[0027] Finally, for (Ba) 1-y Re y (Bi) 1-x R x The negative temperature coefficient thermistor material of the present invention is obtained by pressing and sintering O3 powder into blocks. Example 1

[0028] 101. Add 16.13g of bismuth oxide and 13.09739g of barium carbonate in sequence, mix for 1 hour, and then add 0.77261g of lead oxide for mixing. The molar ratio of Ba, Pb and Bi elements at this time is calculated to be 0.95 : 0.05 : 1.

[0029] 102. Place the obtained mixture in a polytetrafluoroethylene container, add agate balls, dispersant, and binder (PVB) and ball mill (the mass ratio of the mixture, agate balls, and dispersant is 1:1:4, and the volume ratio of anhydrous ethanol to glycerol in the dispersant is 1:9). The mass of the binder is 3% of the mass of the mixture. Ball mill for 18 hours to obtain the mixed powder.

[0030] 103. The mixed powder was calcined in air at 700°C for 2 hours to obtain Ba. 0.95 Pb 0.05 BiO3 calcined materials.

[0031] 104. General 0.95 Pb 0.05 BiO3 calcined material was ground in an agate mortar to obtain Ba. 0.95 Pb 0.05 BiO3 powder was uniaxially compressed at a pressure of 2 MPa for 30 seconds, and then further cold isostatically pressed at 280 MPa for 350 seconds to obtain a Ф25×1.8mm block.

[0032] 105. The molded block is placed in calcined zirconium oxide powder and sintered at 800℃ for 3 hours in a high-purity argon atmosphere to obtain a negative temperature coefficient thermistor material with the chemical formula Ba. 0.95 Pb 0.05 BiO3.

[0033] 106. The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were fired at 700℃ for 30 minutes to achieve conductivity. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, it was placed in an ultra-low temperature control device, and resistance-temperature measurements were performed between 40-160K. The thermistor element was aged in liquid nitrogen (77K) for 800 hours, and the aging resistance deviation rate was obtained. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively.

[0034] The negative temperature coefficient thermistor material prepared in Example 1 uses Ba 0.95 Pb 0.05 BiO3 indicates that its preparation process is as follows: Figure 1 As shown, the X-ray diffraction pattern of the material is shown in the figure. Figure 2 The diffraction peaks located at 29.0°, 41.4°, 46.6°, 51.3°, 60.1°, 68.0°, 75.6° and 82.8° correspond to the characteristic peaks of perovskite BaBiO3 (Powder Diffraction Card Standard Library PDF#38-1150).

[0035] like Figure 3 As shown, by Figure 3 Ba can be seen 0.95 Pb 0.05 BiO3 consists of uniform grains and grain boundaries. The surface morphology shows no obvious cracks or pores, indicating that Example 1 prepared a relatively dense ceramic body. The overall grain size distribution ranges from 1.8 to 2.1 μm and follows a normal distribution.

[0036] In this embodiment, a uniaxial pressing method is used to press the powder into shape, perform cold isostatic pressing, and sinter to form Ba. 0.95 Pb 0.05 BiO3 thermistor material, with stable properties of Ba 0.95 Pb 0.05 BiO3 is used as the material for thermistors, and is sintered under a specific atmosphere. 0.95 Pb 0.05 Pb at site A in BiO3 2+ relatively 2+ The similarity between valence state and ionic radius enhances structural stability and improves the material's anti-aging properties. Na + / K + Compare 3+ Due to the significant difference in valence states, doping introduces donor levels, increases carrier concentration, and reduces the jumping energy barrier, thereby optimizing the electrical characteristics in different temperature ranges. Example 2

[0037] This invention provides a second method for preparing a thermistor material, comprising the following steps: 201. Add 16.10764g of bismuth oxide and 12.73505g of barium carbonate in sequence, mix for 1 hour, and then add 1.15731g of lead oxide for mixing. The molar ratio of Ba, Pb and Bi elements at this time is calculated to be 0.925 : 0.075 : 1.

[0038] 202. Place the obtained mixture in a polytetrafluoroethylene container, add agate balls, dispersant, and binder (PVB) and ball mill (the mass ratio of the mixture, agate balls, and dispersant is 1:1:4, the volume ratio of anhydrous ethanol to glycerol in the dispersant is 3:7, and the mass of the binder is 3.5% of the mass of the mixture, and ball mill for 18 hours to obtain a mixed powder).

[0039] 203. The mixed powder was calcined in air at 725°C for 2.5 h to obtain Ba. 0.925 Pb 0.075 BiO3 calcined materials.

[0040] 204. General 0.925 Pb 0.075 The calcined BiO3 material was ground in an agate mortar to obtain Ba. 0.925 Pb 0.075 BiO3 powder was uniaxially compressed at a pressure of 2.5 MPa for 70 s, and then further cold isostatically pressed at 280 MPa for 360 s to obtain a Ф25×1.8 mm block.

[0041] 205. The molded block is placed in calcined zirconium oxide powder and sintered at 825℃ for 4 hours in a high-purity argon atmosphere to obtain the negative temperature coefficient thermistor material Ba. 0.925 Pb 0.075 BiO3.

[0042] 206. The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were fired at 700℃ for 30 minutes to achieve conductivity. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, it was placed in an ultra-low temperature measuring device, and its resistance-temperature was measured between 40-160K. 0.925 Pb 0.075 BiO3 thermistor elements were aged in liquid nitrogen (77K) for 800 hours to obtain the aged resistance deflection rate. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively. Example 3

[0043] This invention provides a third method for preparing a thermistor material, comprising the following steps: 301. Add 16.08535g of bismuth oxide and 12.37371g of barium carbonate in sequence, mix for 1 hour, and then add 1.54094g of lead oxide for mixing. The molar ratio of Ba, Pb and Bi elements at this time is calculated to be 0.9 : 0.1 : 1.

[0044] 302. Place the obtained mixture in a polytetrafluoroethylene container, add agate balls, dispersant, and binder (PVB) and ball mill (the mass ratio of the mixture, agate balls, and dispersant is 1:1:4, the volume ratio of anhydrous ethanol to glycerol in the dispersant is 3:7, and the mass of the binder is 3.5% of the mass of the mixture, and ball mill for 19 hours to obtain a mixed powder).

[0045] 303. The mixed powder was calcined in air at 750°C for 2.5 h to obtain Ba. 0.9 Pb 0.1 BiO3 calcined materials.

[0046] 304. General 0.9 Pb 0.1 The calcined BiO3 material was ground in an agate mortar to obtain Ba. 0.9 Pb 0.1 BiO3 powder was uniaxially compressed at a pressure of 3 MPa for 70 s, and then further cold isostatically pressed at 280 MPa for 360 s to obtain a Ф25×1.8 mm block.

[0047] 305. The molded block is placed in calcined zirconium oxide powder and sintered at 850℃ for 4 hours in a high-purity argon atmosphere to obtain the negative temperature coefficient thermistor material Ba. 0.9 Pb 0.1 BiO3.

[0048] 306. The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were fired at 700℃ for 30 minutes to achieve conductivity. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, it was placed in an ultra-low temperature measuring device, and its resistance-temperature was measured between 40-160K. 0.9 Pb 0.1 BiO3 thermistor elements were aged in liquid nitrogen (77K) for 800 hours to obtain the aged resistance deflection rate. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively. Example 4

[0049] This invention provides a fourth method for preparing a thermistor material, comprising the following steps: 401. Add 16.67139g of bismuth oxide and 12.82452g of barium carbonate in sequence, mix for 1 hour, and then add 0.50408g of potassium carbonate for further mixing. The molar ratio of Ba, Bi and K at this time is calculated to be 1:0.9:0.1.

[0050] 402. Place the obtained mixture in a polytetrafluoroethylene container, add agate balls, dispersant, and binder (PVB) and ball mill (the mass ratio of the three is 1:1:4, the volume ratio of anhydrous ethanol to glycerol in the dispersant is 7:3, the mass of the binder is 4% of the mass of the mixture, and ball mill for 19 hours to obtain a mixed powder).

[0051] 403. The mixed powder was calcined in air at 650°C for 3 hours to obtain BaBi. 0.9 K 0.1 O3 calcined materials.

[0052] 404. BaBi 0.9 K 0.1 The calcined material was ground in an agate mortar and pestle to obtain BaBi. 0.9 K 0.1 O3 powder was uniaxially compressed at a pressure of 3.5 MPa for 70 seconds, and then further cold isostatically pressed at 280 MPa for 370 seconds to obtain a Ф25×1.8 mm block.

[0053] 405. The molded block is placed in calcined zirconium oxide powder and sintered at 750℃ for 5 hours in a high-purity argon atmosphere to obtain the negative temperature coefficient thermistor material BaBi. 0.9 K 0.1 O3.

[0054] 406. The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were fired at 700℃ for 30 minutes to perform conductivity conversion. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, it was placed in an ultra-low temperature measuring device, and resistance-temperature measurements were performed between 40-160K. The thermistor element was aged in liquid nitrogen (77K) for 800 hours, and the aging resistance deviation rate was obtained. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively.

[0055] The negative temperature coefficient thermistor material prepared in Example 4 uses BaBi 0.9 K 0.1 O3 indicates that the X-ray diffraction pattern is as follows: Figure 4As shown, the diffraction peaks at 20.5°, 29.0°, 41.4°, 46.6°, 51.3°, 60.1°, 64.4°, 68.0°, 75.6°, and 82.8° correspond to the characteristic peaks of perovskite BaBiO3 (PDF#38-1150). Simultaneously, the diffraction peaks shift generally to lower angles; according to Bragg's diffraction law, this is due to the larger ionic radius of element K. + (1.38 Å) Partially replaces Bi, an element with a smaller ionic radius. 3+ This is caused by (1.03 Å). Example 5

[0056] This invention provides a fifth method for preparing a thermistor material, comprising the following steps: 501. Add 16.74022g of bismuth oxide and 12.87747g of barium carbonate in sequence, mix for 1 hour, and then add 0.38231g of sodium carbonate for mixing. The molar ratio of Ba, Bi and Na elements at this time is calculated to be 1: 0.9: 0.1.

[0057] 502. Place the obtained mixture in a polytetrafluoroethylene container, add agate balls, dispersant, and binder (PVB) and ball mill (the mass ratio of the three is 1:1:4, the volume ratio of anhydrous ethanol to glycerol in the dispersant is 9:1, the mass of the binder is 5% of the mass of the mixture, and ball mill for 20 hours to obtain a mixed powder).

[0058] 503. The mixed powder was calcined in air at 700°C for 4 hours to obtain BaBi. 0.9 Na 0.1 O3 calcined materials.

[0059] 504. BaBi 0.9 Na 0.1 The calcined material was ground in an agate mortar and pestle to obtain BaBi. 0.9 Na 0.1 O3 powder was uniaxially compressed at a pressure of 4 MPa for 90 seconds, and then further cold isostatically pressed at 280 MPa for 380 seconds to obtain a Ф25×1.8mm block.

[0060] 505. The molded block is placed in calcined zirconium oxide powder and sintered at 800℃ for 5 hours in a high-purity argon atmosphere to obtain the negative temperature coefficient thermistor material BaBi. 0.9 Na 0.1 O3.

[0061] 506. The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were fired at 700℃ for 30 minutes to perform conductivity conversion. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, it was placed in an ultra-low temperature measuring device, and resistance-temperature measurements were performed between 40-160K. The thermistor element was aged in liquid nitrogen (77K) for 800 hours, and the aging resistance deviation rate was obtained. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively.

[0062] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that 16.04095g of bismuth oxide and 11.65402g of barium carbonate were mixed for 1 hour, and then 2.30503g of lead oxide was added and mixed again. The chemical formula of the obtained thermistor material is Ba. 0.85 Pb 0.15 BiO3.

[0063] The ceramic block was sliced, and silver-palladium paste was screen-printed. Electrodes were then calcined at 835℃ for 30 minutes to achieve conductivity. After dicing, a 1.0mm × 1.0mm × 0.35mm thermistor chip was obtained. After soldering leads, the chip was placed in a cryogenic measuring device, and resistance-temperature measurements were performed between 40 and 160 K. The thermistor element was then aged in liquid nitrogen (77K) for 800 hours, and the aging resistance shift rate was obtained. R1 and R0 are the resistance values ​​of the component before and after aging at 77K, respectively.

[0064] Comparative Example 2 The only difference between Comparative Example 2 and Example 4 is that 16.93125g of bismuth oxide and 11.57726g of barium carbonate were mixed for 1 hour, and then 0.76791g of potassium carbonate was added for further mixing. The resulting thermistor material has the chemical formula BaBi. 0.8 K 0.2 O3.

[0065] The ceramic block was sliced, and silver-palladium paste was screen-printed. The electrodes were then calcined at 700℃ for 30 minutes to conduct conductivity. After dicing, a 1.0mm×1.0mm×0.35mm thermistor chip was obtained. After soldering the leads, it was placed in an ultra-low temperature measuring device, and the resistance-temperature was measured at 40-160 K.

[0066] Comparative Example 3 The only difference between Comparative Example 3 and Example 4 is that 16.1749g of bismuth oxide and 13.8251g of barium carbonate were used to obtain a thermistor material with the chemical formula BaBiO3.

[0067] The ceramic block was sliced, and silver-palladium paste was screen-printed. The electrodes were then calcined at 700℃ for 30 minutes to conduct conductivity. After dicing, a 1.0mm×1.0mm×0.35mm thermistor chip was obtained. After soldering the leads, it was placed in an ultra-low temperature measuring device, and the resistance-temperature was measured at 40-160 K.

[0068] Comparative Example 4 The difference between Comparative Example 4 and Example 5 is that the thermosensitive material was sintered in air, and the resulting thermosensitive material has the chemical formula BaBi. 0.9 Na 0.1 O3.

[0069] The ceramic block was sliced, and silver-palladium paste was screen-printed. The electrodes were then calcined at 700℃ for 30 minutes to conduct conductivity. After dicing, a 1.0mm×1.0mm×0.35mm thermistor chip was obtained. After soldering the leads, it was placed in an ultra-low temperature measuring device, and the resistance-temperature was measured at 40-160 K.

[0070] Example 4 BaBi was prepared by sintering in high-purity argon gas. 0.9 K 0.1 O3, Example 5 BaBi 0.9 Na 0.1 The resistivity of O3 and these two types of thermistors and B 40 / 160K The range of values ​​is: 2.3 × 10 5 ~3.0×10 6 Ω·cm and 368~434K. Among them, BaBi... 0.9 Na 0.1 O3 has the lowest resistivity, at 2.3 × 10⁻⁶. 5 The material constant is minimal, with a Ω·cm, and a minimum material constant of 368 K. This is the BaBi sintered in air as a comparative example 4. 0.9 Na 0.1 O3, its resistivity 1.5×10 6 Ω·cm, material constant B 40 / 160K It is 773K. BaBi 0.9 Na 0.1 resistivity of O3 The resistivity exhibits a curved relationship with temperature T, and rises rapidly with increasing temperature, demonstrating the characteristics of a negative temperature coefficient. Figure 5 As shown. Ba in Examples 1 and 3 0.95 Pb 0.05 BiO3 and Ba 0.9 Pb 0.1 BiO3, its resistivity They are 1.6×10 6and 5.4×10 6 Ω·cm, material constant B 40 / 160K The values ​​are 597K and 634K. Therefore, compared to other thermistors, BBNO / BBKO are particularly suitable for measurement and control at extremely low temperatures, as well as for stable measurements.

[0071] like Figure 6 As shown, Ba was prepared from Examples 2-3 and Comparative Example 3. 0.925 Pb 0.075 BiO3, Ba 0.9 Pb 0.1 The aging resistance shift rate diagrams of BiO3 and BaBiO3 ultra-low temperature thermistor ceramics show that Ba 0.9 Pb 0.1 The resistivity aging shift rate of the BiO3 sample was 1.7%, and that of BaBiO3 was 7.9%. This shows that appropriate lead ion doping can improve the anti-aging performance of the material.

[0072] like Figure 7 The figure shown is Ba obtained from Comparative Example 1. 0.85 Pb 0.15 XRD patterns of BiO3 materials. (Example: ...) Figure 7 As shown, the diffraction peaks at 29.0°, 41.4°, 46.6°, 51.3°, 60.1°, 68.0°, 75.6°, and 82.8° correspond to the characteristic peaks of perovskite BaBiO3 (PDF#38-1150). The peaks at 24.1°, 25.9°, 27.7°, and 33.4° are impurity peaks of the second phase, indicating the presence of a second phase. This suggests that when the lead content is 0.15, the material has a two-phase structure. The two-phase structure undergoes a phase transition at high temperatures, leading to a decrease in material stability.

[0073] The resistivity, material constant K, and offset of each material are shown in Table 1. From Examples 1 to 5 and Comparative Examples 1 to 4 above, it can be seen that in Example 5, BaBi... 0.9 Na 0.1 O3 has the lowest resistivity, at 2.3 × 10⁻⁶. 5 Ω·cm, the material constant is the smallest, at 368 K. For Ba 0.9 Pb 0.1 BiO3, with a high-temperature aging resistance shift rate of 1.7%, is a thermistor material formed by mixing multiple oxides using a solid-phase mixing method and reacting under high-purity argon gas. 0.9 Pb 0.1 Pb at site A in BiO3 2+ relatively 2+ Similar to, it enhances the stability of the structure and improves the anti-aging properties of the material. BaBi0.9 Na 0.1 Na at site B in O3 + Compare 3+ Due to the significant difference in valence states, doping introduces donor levels, increases carrier concentration, and reduces the jumping energy barrier, thereby optimizing the electrical characteristics in different temperature ranges.

[0074] Table 1 On the other hand, embodiments of the present invention also provide an application of BBPO / BBNO / BBKO thermistor materials, which are used for temperature environment, especially temperature measurement and control at extremely low temperatures.

[0075] The BBPO / BBNO / BBKO thermistor material prepared by this invention can be used as a thermistor element material with low material constant, low resistivity and small aging resistance offset rate.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A perovskite thermistor material, characterized in that, It is a perovskite phase ceramic material with the chemical formula (Ba). 1-y Re y (Bi) 1-x R x O3; x is 0 or y is 0; When x is 0, Re is Pb, and 0 ≤ y ≤ 0.1; When y is 0, R is Na or K, and 0 ≤ x ≤ 0.

15.

2. A perovskite thermistor material according to claim 1, characterized in that, Prepared by the following steps: 1) Weigh the raw materials according to the proportions. The molar ratio of each raw material, calculated by metal element, is as follows: When x is 0, the molar ratio of barium carbonate, lead oxide, and bismuth oxide is 0.9-1 : 0.0-0.1 :

1. When y is 0, the molar ratio of barium carbonate, bismuth oxide, sodium carbonate, or potassium carbonate is 1 : 0.85-1 : 0-0.

15. 2) Add barium carbonate, bismuth oxide, and one of lead oxide, sodium carbonate, and potassium carbonate in sequence, and mix for 1-3 hours; 3) Place the mixture obtained in step 2) into a polytetrafluoroethylene container, add agate balls, dispersant and binder, and ball mill to obtain a mixed powder; 4) The mixed powder was calcined in air to obtain (Ba 1-y Re y (Bi) 1-x R x O3 calcined materials; 5) The calcined (Ba) 1-y Re y (Bi) 1-x R x The calcined material was added to an agate mortar and ground to obtain (Ba 1-y Re y (Bi) 1-x R x O3 powder; then (Ba 1-y Re y (Bi) 1-x R x O3 powder briquettes; 6) After pressing (Ba) 1-y Re y (Bi) 1-x R x O3 blocks were placed in buried sintering powder and sintered under an atmosphere to obtain the chemical formula (Ba). 1-y Re y (Bi) 1-x R x The perovskite thermistor material of O3.

3. The perovskite thermistor material according to claim 2, characterized in that, In step 3), the mass ratio of the mixture, agate balls, and dispersant is 1:1:4; the mass of the binder is 3%-5% of the mass of the mixture; and the ball milling time is 18-20 hours.

4. The perovskite thermistor material according to claim 3, characterized in that, The dispersant is a mixture of anhydrous ethanol and glycerol; wherein the volume ratio of anhydrous ethanol to glycerol is (1~9):(1~9).

5. The perovskite thermistor material according to claim 2, characterized in that, The calcination temperature in step 4) is 650-750℃, and the calcination time is 2-6h.

6. The perovskite thermistor material according to claim 2, characterized in that, The pressing block in step 5) includes the following steps: The (Ba) 1-y Re y (Bi) 1-x R x O3 powder is uniaxially compressed into blocks at a pressure of 2-4 MPa for 30-90 seconds.

7. The perovskite thermistor material according to claim 6, characterized in that, The pressing block in step 5) further includes cold isostatic pressing at a pressure of 280MPa for 350-380s to obtain a Ф25×1.8mm block.

8. The perovskite thermistor material according to claim 2, characterized in that, The sintering temperature in step 6) is 700℃-850℃, the sintering time is 3-5h, and the sintering atmosphere is high-purity argon.

9. The perovskite thermistor material according to claim 2, characterized in that, The calcined powder in step 6) is zirconium oxide powder.

10. An application of the perovskite thermistor material according to any one of claims 1-9, characterized in that, It is used for temperature measurement and control, especially for temperature measurement and control at extremely low temperatures of 40-160K.

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