Multi-element high-entropy oxide thermal sensitive ceramic, thermistor and preparation method and application of multi-element high-entropy oxide thermal sensitive ceramic

Abstract

The invention relates to a multi-element high-entropy oxide thermal sensitive ceramic, a thermistor and a preparation method and application of the multi-element high-entropy oxide thermal sensitive ceramic, oxides with different valence states are used as initial raw materials, a binary spinel phase powder material is synthesized in advance, and then ball-milling mixing, grinding, calcining, cold isostatic pressing forming and sintering are performed to obtain the high-entropy oxide thermal sensitive ceramic. The thermistor is obtained through the thermal sensitive ceramic, the thermistor has obvious NTC (Negative Temperature Coefficient) characteristics at-75 DEG C to 75 DEG C, and the electrical property parameters of the thermistor are as follows: B25 / 50 is equal to 3600K to 4900K, rho25 is equal to 1.95 * 10 < 4 > omega.cm to 6.13 * 10 < 6 > omega.cm, and the aging drift rate is less than or equal to 0.05% when the thermistor is aged at 125 DEG C for 500h. The thermal sensitive ceramic and the thermistor are stable in performance and good in consistency, the electrical performance parameters of the thermal sensitive ceramic and the thermistor can be regulated and controlled by adjusting the type of the binary spinel phase powder material, and the thermal sensitive ceramic and the thermistor are suitable for manufacturing the thermistor for ocean temperature measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of thermistor materials, and in particular to a multi-element high entropy oxide thermistor ceramic, a thermistor, and a preparation method and application thereof. Background Art

[0002] Negative Temperature Coefficient (NTC) thermistor material is a material whose resistance decreases exponentially with increasing temperature. The way it conducts electricity is completely similar to semiconductor materials such as germanium and silicon. When the temperature is low, the number of carriers (electrons and holes) in the material is small, making the thermistor resistance higher; as the temperature rises, the number of carriers increases, making the thermistor resistance decrease. This type of material is usually made of two or more oxides of transition metal elements such as Mn, Co, Ni, Cu, Zn, Cr and Fe, and is prepared by traditional semiconductor ceramic technology. Thermistors made of this type of NTC material have high sensitivity and stability, good reliability, and low price. They are widely used in temperature measurement and control, temperature compensation, and surge current suppression. With the development of science and technology, the requirements for temperature measurement in various fields have increased, which requires NTC thermistors to be able to respond to temperature changes faster, have a higher tolerance to the environment, and have a longer service life. In practical applications, the electrical properties and stability of thermistors determine the use environment of NTC thermistors, and the main factors affecting the electrical properties of spinel NTC thermistors are the distribution and microstructure of cations. Therefore, under the condition of ensuring that the thermistor has a suitable resistivity and material constant B value, designing a thermistor with a stable structure is the key to preparing a highly stable thermistor.

[0003] With the continuous deepening of high entropy alloy research, the concept of high entropy has gradually expanded to other materials, such as high entropy metallic glass, high entropy ceramics, high entropy thermoelectric materials, high entropy polymers, etc. Compared with traditional ceramic materials, high entropy ceramic materials show better mechanical properties, high temperature stability, catalytic properties, electrical properties, lithium ion storage performance, etc. due to the high entropy effect in thermodynamics, the hysteresis diffusion effect in kinetics, the lattice distortion effect in structure, and the "cocktail" mixed effect in performance, which has attracted extensive research by scientific researchers. If the NTC thermistor is designed as a high entropy ceramic, the diffusion rate of its cations will be reduced, the distribution of cations will be difficult to change, and the stability of the high entropy NTC thermistor will be greatly improved. The current high entropy oxide thermistor material has unstable performance and poor consistency. Therefore, a high entropy oxide thermistor material with stable performance is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-element high entropy oxide thermistor and a preparation method and application thereof. The thermistor uses oxides of cobalt, manganese, iron, zinc, nickel, chromium, magnesium and aluminum in different valence states as initial raw materials, synthesizes binary spinel phase powder materials in advance, and then undergoes ball milling, grinding, calcination, cold isostatic pressing and sintering to obtain a high entropy oxide thermistor. The high entropy oxide thermistor described in the present invention has obvious NTC characteristics within -75°C to 75°C, and its electrical performance parameters are: B 25 / 50 =3598K-4900K,ρ 25 =1.95×10 4 Ω·cm-6.13×10 6 Ω·cm, aged at 125°C for 500h, aging drift rate ≤0.05%. The high entropy oxide thermistor of the present invention has stable performance and good consistency. The electrical performance parameters can be adjusted by adjusting the type of binary spinel phase powder material, and is suitable for manufacturing thermistors for ocean temperature measurement or manufacturing temperature sensors using thermistors.

[0005] The present invention provides a method for preparing a multi-element high entropy oxide thermosensitive ceramic, comprising the following steps:

[0006] 1) Using a plurality of oxides as raw materials, weighing three or more groups of oxides respectively according to the stoichiometric ratio of AB2O4, mixing each group of oxides separately, and adding a solvent to each group of oxides respectively to obtain three or more groups of mixtures; wherein each group of oxides is composed of oxides of two different metal element types;

[0007] 2) drying and calcining each group of mixtures in step 1) respectively to obtain three or more binary spinel phase powders;

[0008] 3) Mix the three or more binary spinel phase powders obtained in step 2), dry, shape and sinter to obtain a multinary high entropy oxide thermistor ceramic, wherein the multinary high entropy oxide is a high entropy oxide of five or more elements.

[0009] Preferably, in step 1), the oxide comprises manganese oxide, cobalt oxide, nickel oxide, iron oxide, zinc oxide, magnesium oxide, chromium oxide and / or aluminum oxide;

[0010] Wherein, the manganese oxide includes one or more of manganese dioxide, manganese trioxide and manganese tetraoxide; the cobalt oxide includes cobalt trioxide and / or cobalt tetraoxide; the nickel oxide includes nickel oxide and / or nickel trioxide; the iron oxide includes ferric oxide and / or ferroferric oxide; and / or,

[0011] The binary spinel phase powder in step 2) includes NiFe2O4, NiMn2O4, MgAl2O4, CoMn2O4, ZnMn2O4, NiAl2O4, MnFe2O4, ZnCo2O4, CoCr2O4 and / or MgMn2O4.

[0012] Preferably, the solvent in step 1) is a mixture of water and ethanol, or water and methanol, the volume ratio of water to ethanol is 1:0.5-1.2, or the volume ratio of water to methanol is 1:0.5-1.2.

[0013] Preferably, in step 2), the drying temperature of each group of mixtures is 75-95° C., the calcination temperature is 850° C.-1500° C., and the calcination time is 2 h to 12 h.

[0014] Preferably, in step 3), after the powder is ground, the 2 The pre-pressing is performed at a pressure of 10-15s, the formed block is cold isostatically pressed, the pressure is maintained at 200-380MPa for 1-4min, and then the block is sintered at 1125-1600℃ for 3h to 12h.

[0015] The invention provides a multi-component high-entropy oxide thermosensitive ceramic, which is prepared by the preparation method.

[0016] The invention provides a thermistor, wherein the thermistor comprises the multi-element high entropy oxide thermistor ceramic.

[0017] Preferably, the method for preparing the thermistor comprises the following steps:

[0018] The surface of the multi-element high entropy oxide thermistor ceramic is coated with silver paste and the electrode is sintered to obtain the high entropy oxide thermistor material.

[0019] Preferably, the temperature range of the multi-element high entropy oxide thermistor is -75°C to 75°C, and the electrical performance parameters are: B 25 / 50 =3600K~4900K,ρ 25 =1.95×10 4 Ω·cm~6.13×10 6 Ω·cm.

[0020] The present invention provides an application of the multi-element high entropy oxide thermistor ceramic in manufacturing a marine temperature measuring resistor or a temperature sensor;

[0021] The invention provides an application of the thermistor in manufacturing a marine temperature measuring resistor or a temperature sensor.

[0022] More specifically, the present invention provides a multinary high-entropy oxide thermistor, a thermistor, and a preparation method and application thereof, wherein oxides of different valence states are used as initial raw materials, a binary spinel phase powder material is pre-synthesized, and then ball milling, grinding, calcining, cold isostatic pressing, and sintering are performed to obtain a high-entropy oxide thermistor.

[0023] The thermal sensitive ceramic is mainly prepared with manganese dioxide or manganese trioxide or manganese tetraoxide, cobalt trioxide or cobalt tetraoxide, nickel oxide or nickel trioxide, iron trioxide or iron tetraoxide, zinc oxide, magnesium oxide, chromium trioxide and aluminum trioxide as raw materials; the mixed oxide containing cobalt, manganese, iron, zinc, nickel, chromium, magnesium and aluminum is composed of five or more oxides.

[0024] The thermistor ceramic uses oxides of different valence states as initial raw materials, and according to the AB2O4 stoichiometric ratio, pre-designs and synthesizes several binary spinel phase powder materials, such as NiFe2O4, NiMn2O4, MgAl2O4, CoMn2O4, ZnMn2O4, NiAl2O4, MnFe2O4, ZnCo2O4, CoCr2O4, MgMn2O4, etc.

[0025] The thermosensitive ceramic is composed of a mixture of three or more binary spinel phase powder materials.

[0026] More specifically, the present invention provides a method for preparing a multi-element high entropy oxide thermistor, comprising the following steps:

[0027] a. Select five or more oxides as raw materials: manganese dioxide or dimanganese trioxide or trimanganese tetraoxide, cobalt trioxide or tricobalt tetraoxide, nickel oxide or dinickel trioxide, ferric oxide or ferric oxide, zinc oxide, magnesium oxide, chromium trioxide and aluminum trioxide. According to the stoichiometric ratio of AB2O4, weigh two different types of the above oxides, put them into a ball mill, add deionized water and anhydrous ethanol in a solvent volume ratio of 1:1, place the ball mill in a planetary ball mill, and grind for 10 hours to obtain an oxide mixture;

[0028] b. Dry the mixture in step a in an oven at 85° C., grind it, and then calcine it at 850-1500° C. for 2 h to 12 h to melt it into a high-entropy oxide powder material with a single spinel structure, and obtain a variety of binary spinel phase oxides, such as NiFe2O4, NiMn2O4, MgAl2O4, CoMn2O4, ZnMn2O4, NiAl2O4, MnFe2O4, ZnCo2O4, CoCr2O4, MgMn2O4, etc.;

[0029] c. The high entropy oxide powder material obtained in step b, three or more spinel phase powder materials are subjected to secondary ball milling in a planetary ball mill for 10 hours, dried, and ground to obtain uniformly dispersed powders;

[0030] d. The powder obtained in step c is heated to 15-20 kg / cm 2 The pre-pressing is performed at a pressure of 10-15s, the formed block is cold isostatically pressed, the pressure is maintained at 300MPa for 3min, and then the block is sintered at 1125-1600℃ for 3h~12h to obtain high entropy oxide thermistor ceramics.

[0031] e. Apply silver paste to the upper and lower surfaces of the high entropy oxide ceramic sintered in step d, and sinter and infiltrate electrodes at 850° C. to obtain a high entropy oxide thermistor. The thickness of the electrode is 10-20 μm.

[0032] The temperature range of the thermistor prepared by the present invention is -75℃~75℃, and the electrical performance parameters are: 25 / 50 =3600K~4900K,ρ 25 =1.95×10 4 Ω·cm~6.13×10 6 Ω·cm.

[0033] The present invention studies the influence of oxide raw materials with different valence states on the microstructure and performance of a high entropy oxide negative temperature coefficient thermistor, and suitable raw materials can be selected according to the resistivity of the target material and the material constant B value.

[0034] The present invention can adjust the type of pre-synthesized binary spinel phase powder material, increase the configuration entropy of the high entropy system, and regulate its electrical performance parameters, and is suitable for manufacturing thermistors for ocean temperature measurement.

[0035] The beneficial effects of the present invention are:

[0036] The high entropy oxide thermistor and thermistor described in the present invention have stable performance and good consistency. The electrical performance parameters can be regulated by adjusting the type of binary spinel phase powder material. They are suitable for manufacturing thermistors and thermistors for ocean temperature measurement, or for manufacturing temperature sensors using thermistors and thermistors. DETAILED DESCRIPTION

[0037] The present invention is further illustrated by the following examples, but the scope of the present invention is not limited thereto.

[0038] Example 1

[0039] a. According to the stoichiometric ratio of metal elements of 1:2, cobalt trioxide and manganese trioxide, nickel oxide and ferrous oxide, zinc oxide and cobalt oxide were weighed and placed in a ball mill respectively. Deionized water and anhydrous ethanol were added in a solvent volume ratio of 1:1. The ball mill was placed in a planetary ball mill and ground for 10 hours to obtain a mixture of the three oxides.

[0040] b. The three mixtures in step a were dried in an oven at 85° C., ground, and then calcined at 1100° C., 1000° C., and 850° C. for 2 h, respectively, to synthesize three binary spinel phase powder materials;

[0041] c. Place the binary spinel powder material obtained in step b in a planetary ball mill for secondary ball milling for 10 hours, dry, and grind to obtain a uniformly dispersed powder;

[0042] d. The powder obtained in step c was heated to 20 kg / cm 2 The pre-pressing was performed at a pressure of 15 s, the formed block was cold isostatically pressed at a pressure of 300 MPa for 3 min, and then the block was sintered at 1200°C for 3 h to obtain high entropy oxide thermistors.

[0043] e. Apply silver paste to the upper and lower surfaces of the high entropy oxide ceramic sintered in step d, and sinter the electrodes at 850° C. to obtain a high entropy oxide thermistor material.

[0044] The obtained high entropy oxide negative temperature coefficient thermistor material was subjected to electrical performance testing, and the obtained electrical parameters were B 25 / 50 =4008K,ρ 25 =1.95×10 4 Ω·cm, aged at 125℃ for 500h, the aging drift rate is 0.78%. The resistor has excellent aging stability and can be used in seawater temperature measurement and control.

[0045] Example 2

[0046] a. Cobalt trioxide and manganese oxide (including equimolar amounts of manganese tetraoxide and manganese dioxide), nickel oxide and ferric oxide, zinc oxide and cobalt trioxide are weighed respectively according to the stoichiometric ratio of metal elements of 1:2, and the above oxides are weighed and put into a ball mill, and deionized water and anhydrous ethanol are added in a solvent volume ratio of 1:1, and the ball mill is placed in a planetary ball mill and ground for 10 hours to obtain a mixture of the three oxides;

[0047] b. The three mixtures in step a were dried in an oven at 80° C., ground, and then calcined at 1100° C., 1000° C., and 950° C. for 4 h, respectively, to synthesize three binary spinel phase powder materials;

[0048] c. All the spinel phase powder materials in step b are subjected to secondary ball milling for 10 hours in a planetary ball mill, dried, and ground to obtain uniformly dispersed powders;

[0049] d. The powder obtained in step c was heated to 18 kg / cm 2 The pre-pressing was performed at a pressure of 15 s, the formed block was cold isostatically pressed at a pressure of 320 MPa for 4 min, and then the block was sintered at 1300 ° C for 6 h to obtain high entropy oxide thermistor ceramics.

[0050] e. Apply silver paste to the upper and lower surfaces of the high entropy oxide ceramic sintered in step d, and sinter the electrodes at 850° C. to obtain a high entropy oxide thermistor material.

[0051] The obtained high entropy oxide negative temperature coefficient thermistor material was subjected to electrical performance testing, and the obtained electrical parameters were B 25 / 50 =4260K,ρ 25 =7.88×10 4 Ω·cm, aged at 125℃ for 500h, the aging drift rate is 0.43%. The resistor has excellent aging stability and can be used in seawater temperature measurement and control.

[0052] Example 3

[0053] a. Magnesium oxide and manganese oxide (equal molar amounts of manganese tetraoxide and manganese dioxide), nickel oxide and iron oxide (equal molar amounts of ferric tetroxide and ferric oxide), zinc oxide and cobalt trioxide are weighed according to the stoichiometric ratio of metal elements of 1:2, and the above oxides are weighed and put into a ball mill, and deionized water and anhydrous ethanol are added in a solvent volume ratio of 1:1. The ball mill is placed in a planetary ball mill and ground for 10 hours to obtain a mixture of the three oxides;

[0054] b. The three mixtures in step a are dried in an oven at 85° C., ground, and then calcined at 1200° C., 1000° C. and 950° C. for 8 h, respectively, to synthesize three binary spinel phase powder materials;

[0055] c. The powder material obtained in step b is placed in a planetary ball mill for secondary ball milling for 10 hours, dried, and ground to obtain a uniformly dispersed powder;

[0056] d. The powder obtained in step c is 20Kg / cm 2 The pre-pressing was performed at a pressure of 20 s, the formed block was cold isostatically pressed at a pressure of 280 MPa for 3 min, and then the block was sintered at 1350°C for 8 h to obtain high entropy oxide thermistors.

[0057] e. Apply silver paste to the upper and lower surfaces of the high entropy oxide ceramic sintered in step d, and sinter the electrodes at 850° C. to obtain a high entropy oxide thermistor material.

[0058] The electrical performance of the obtained high entropy oxide negative temperature coefficient thermistor material was tested, and the electrical parameters obtained were B 25 / 50 =4191K,ρ 25 =1.17×10 5 Ω·cm, aged at 125℃ for 500h, the aging drift rate is 0.31%. This resistor has excellent aging stability and can be used in seawater temperature measurement and control.

[0059] Example 4

[0060] a. According to the stoichiometric ratio of metal elements of 1:2, weigh the oxides of magnesium oxide and manganese (equal molar amounts of manganese tetraoxide and manganese dioxide), nickel oxide and iron oxide (equal molar amounts of ferric iron oxide and ferric oxide), magnesium oxide and aluminum oxide, zinc oxide and manganese oxide, chromium oxide and cobalt trioxide, weigh the above oxides, put them into a ball mill, add deionized water and anhydrous ethanol in a solvent volume ratio of 1:1.2, place the ball mill in a planetary ball mill, grind for 10 hours, and obtain a mixture of five oxides;

[0061] b. The five mixtures in step a were dried in an oven at 85° C., ground, and then calcined at 1200° C., 1000° C., 1500° C., 1200° C. and 1300° C. for 6 h, respectively, to synthesize five binary spinel phase powder materials;

[0062] c. Place the powder material obtained in step b in a planetary ball mill for secondary ball milling for 10 hours, dry, and grind to obtain a uniformly dispersed powder;

[0063] d. The powder obtained in step c was heated to 20 kg / cm 2 The pre-pressing was performed at a pressure of 15 s, the formed block was cold isostatically pressed at a pressure of 300 MPa for 3 min, and then the block was sintered at 1400°C for 5 h to obtain high entropy oxide thermistors.

[0064] e. Apply silver paste to the upper and lower surfaces of the high entropy oxide ceramic sintered in step d, and sinter the electrodes at 850° C. to obtain a high entropy oxide thermistor material.

[0065] The obtained high entropy oxide negative temperature coefficient thermistor material was subjected to electrical performance testing, and the obtained electrical parameters were B 25 / 50 =4900K,ρ 25 =1.3×10 6Ω·cm. After aging for 500h at 125℃, the aging drift rate is 0.05%. The resistor has excellent aging stability and can be used for seawater temperature measurement and control.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a multi-element high entropy oxide thermal-sensitive ceramic, comprising the following steps: 1) Using multiple oxides as raw materials, weighing three or more groups of oxides according to the stoichiometric ratio of AB2O4, mixing each group of oxides separately, and adding solvent to each group of oxides to obtain three or more mixtures; wherein each group of oxides is composed of oxides of two different metals; 2) drying and calcining each group of mixtures in step 1) respectively to obtain three or more binary spinel phase powders; 3) Mix the three or more binary spinel phase powders obtained in step 2), dry, shape and sinter to obtain a multinary high entropy oxide thermistor ceramic, wherein the multinary high entropy oxide is a high entropy oxide of five or more elements.

2. The preparation method according to claim 1, characterized in that: In step 1), the oxide includes manganese oxide, cobalt oxide, nickel oxide, iron oxide, zinc oxide, magnesium oxide, chromium oxide and / or aluminum oxide; Wherein, the manganese oxide includes one or more of manganese dioxide, manganese trioxide and manganese tetraoxide; the cobalt oxide includes cobalt trioxide and / or cobalt tetraoxide; the nickel oxide includes nickel oxide and / or nickel trioxide; the iron oxide includes ferric oxide and / or ferroferric oxide; and / or, The binary spinel phase powder in step 2) includes NiFe2O4, NiMn2O4, MgAl2O4, CoMn2O4, ZnMn2O4, NiAl2O4, MnFe2O4, ZnCo2O4, CoCr2O4 and / or MgMn2O4.

3. The preparation method according to claim 1, characterized in that: In step 1), the solvent is a mixture of water and ethanol, or water and methanol, the volume ratio of water to ethanol is 1:0.5-1.2, or the volume ratio of water to methanol is 1:0.5-1.

2.

4. The preparation method according to claim 1, characterized in that: In step 2), the drying temperature of each mixture is 75-95° C., the calcination temperature is 850° C.-1500° C., and the calcination time is 2 h to 12 h.

5. The preparation method according to claim 1, characterized in that: In step 3), the powder is ground at 15-20 kg / cm 2 The pre-pressing is performed at a pressure of 10-15s, the formed block is cold isostatically pressed, the pressure is maintained at 200-380MPa for 1-4min, and then the block is sintered at 1125-1600℃ for 3h to 12h.

6. A multi-element high entropy oxide thermistor ceramic, characterized in that: The multi-element high entropy oxide thermistor ceramic is prepared by the preparation method described in any one of claims 1-5.

7. A thermistor, characterized in that: The thermistor comprises the multi-component high entropy oxide thermistor ceramic according to claim 6.

8. The thermistor according to claim 7, characterized in that: The temperature range of the multi-element high entropy oxide thermistor is -75°C to 75°C, and the electrical performance parameters are: B 25 / 50 =3600K~4900K,ρ 25 =1.95×10 4 Ω·cm~6.13×10 6 Ω·cm.

9. Use of the multi-element high entropy oxide thermistor ceramic according to claim 6 in manufacturing a marine temperature measuring resistor or a temperature sensor.

10. Use of the thermistor according to claim 7 or 8 in manufacturing a marine temperature measuring resistor or a temperature sensor.