Heat-sensitive material with high lift-drag ratio and preparation method of heat-sensitive material

Abstract

The invention relates to a heat-sensitive material with a high lift-to-drag ratio and a preparation method thereof, and belongs to the technical field of preparation of electronic ceramic elements. The preparation method comprises the following steps: mixing nano barium titanate powder and donor-doped barium titanate powder, molding, and sintering to obtain the barium titanate-based thermal sensitive ceramic, the nano barium titanate powder is acceptor doped nano barium titanate powder or undoped nano barium titanate powder; the sintering is carried out under the condition of 1000 to 1500 DEG C for 0.5 to 10 hours. According to the invention, high density and low room temperature resistance are realized, effective oxidation of ceramic grain boundaries can be realized, acceptor doping is realized at the grain boundaries, and the thermal sensitive ceramic has obviously improved thermal sensitive performance. The two-step sintering method preferably adopted by the invention can effectively improve the density of the sintered ceramic and reduce the grain size, is beneficial to improving the performance stability of the thermal sensitive ceramic, and is beneficial to miniaturization of a thermistor with a multi-layer chip structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic ceramic component preparation, and more specifically, relates to a high lift-to-drag ratio thermosensitive material and a preparation method thereof. Background Art

[0002] To produce high-performance barium titanate-based PTC thermistors, a dense ceramic matrix composed of highly semiconducting grains is required to achieve low room-temperature resistance. Furthermore, effective grain-boundary barriers must be formed at the semiconducting grain boundaries to impart thermal sensitivity. These barriers typically arise from the recombination of oxygen vacancies and oxygen adsorption to form grain-boundary acceptor states, often formed during grain-boundary reoxidation. Therefore, to promote grain-boundary oxidation and enhance the PTC effect, the porosity of the ceramic matrix must be controlled. Consequently, the typical preparation of barium titanate-based PTC thermistors requires addressing the trade-off between room-temperature resistance and thermal sensitivity. In addition to forming through recombination of oxygen vacancies and oxygen adsorption, these barriers can also be formed through the doping of grain-boundary acceptor elements such as Mn, Fe, and Na. Furthermore, since these non-oxygen acceptor elements do not volatilize or desorb during long-term use in reducing atmospheres, they exhibit improved reduction resistance. In traditional processes, the above-mentioned acceptor elements are added by directly mixing them with the raw material powders, and it is difficult to control their distribution in the ceramic matrix. Therefore, it is necessary to precisely control the doping content of the acceptor elements to avoid a large amount of carriers in the semiconductor ceramic being recombinated by the acceptors, which leads to a rapid increase in room temperature resistivity.

[0003] In existing processes, while donor element doping is an important means of making PTC thermistor materials semiconductive, literature indicates that the incorporation of the donor La3+ significantly reduces the diffusion rate of oxygen in barium titanate ceramics, thereby inhibiting the recombination of grain boundary oxygen vacancies and the formation of adsorbed oxygen at grain boundaries. Furthermore, literature has shown, through secondary mass spectrometry analysis, that the incorporation of Mn acceptors near grain boundaries can promote the diffusion of grain boundary oxygen. Therefore, it is believed that the improved PTC performance of acceptor-doped thermistors stems from the dual effects of grain boundary reoxidation and the grain boundary acceptor elements. The reduction-reoxidation method, a preparation method that achieves co-firing of ceramics and metal electrodes, is commonly used in the preparation of multilayer chip thermistors. However, in a reducing atmosphere, Mn is easily reduced to a lower valence state, allowing it to enter the grain interior in large quantities. Therefore, the addition of Mn to enhance the PTC effect in the reduction-reoxidation process of barium titanate-based thermistors is rarely used. Summary of the Invention

[0004] In view of the defect that it is difficult to achieve both low room temperature resistance and high lift-to-resistance ratio in the existing barium titanate-based PTC thermistor material process, the present invention provides a preparation method of composite acceptor-doped nano-barium titanate, which can promote the grain boundary oxidation of high-density barium titanate-based thermistor ceramics to form grain boundary barriers, thereby improving the PTC effect.

[0005] According to a first aspect of the present invention, a method for preparing a barium titanate-based thermosensitive ceramic is provided, wherein nano-barium titanate powder and donor-doped submicron barium titanate powder are mixed, molded, and then sintered to obtain a barium titanate-based thermosensitive ceramic; the nano-barium titanate powder is acceptor-doped nano-barium titanate powder or undoped nano-barium titanate powder;

[0006] The sintering is carried out at 1000° C.-1500° C. for 0.5 h-10 h.

[0007] Preferably, the acceptor element in the acceptor-doped nano-barium titanate powder is manganese or iron;

[0008] Preferably, the amount of the acceptor element in the acceptor-doped nano-barium titanate powder accounts for 0.03%-1%.

[0009] Preferably, the particle size of the acceptor-doped nano-barium titanate powder is 10 nm-80 nm.

[0010] Preferably, the mass of the nano-barium titanate powder accounts for 2%-15% of the sum of the mass of the nano-barium titanate powder and the donor-doped submicron barium titanate powder.

[0011] Preferably, the sintering is a two-step sintering, specifically: first sintering at 1225° C.-1425° C. for 2-10 minutes, and then sintering at 1050° C.-1200° C. for 2-10 hours.

[0012] Preferably, the preparation method of the acceptor-doped nano-barium titanate powder is as follows:

[0013] A compound containing an acceptor element and a barium salt are dissolved in water to obtain a first solution; a titanium salt is added to a mixed solvent of ethanol and acetic acid to obtain a second solution; the first solution is added dropwise to the second solution to obtain a mixed solution; the mixed solution is allowed to stand to obtain a mixture gel; the mixture is freeze-dried to obtain a xerogel; the xerogel is ground and calcined to obtain acceptor-doped nano-barium titanate powder;

[0014] Alternatively, a compound containing an acceptor element and a barium salt are dissolved in water to obtain a first solution; the titanium salt is added to a mixed solvent of ethanol and acetic acid to obtain a second solution; the first solution is added dropwise to the second solution to obtain a mixed solution; and the mixed solution is subjected to a hydrothermal reaction to obtain acceptor-doped nano-barium titanate powder;

[0015] Preferably, when the acceptor element is manganese, the compound containing the acceptor element is manganese nitrate; when the acceptor element is iron, the compound containing the acceptor element is ferric chloride or ferric nitrate.

[0016] Preferably, the dry gel is ground and calcined at 600-800° C. for 2-5 hours; the temperature of the hydrothermal reaction is 160-220° C., and the time is 4-20 hours.

[0017] Preferably, the preparation method of the donor-doped submicron barium titanate powder is as follows: barium carbonate, titanium dioxide and donor oxide are ball-milled and then calcined at 1000°C-1200°C for 2-3 hours to obtain donor-doped submicron barium titanate powder with a size of 0.1μm-1μm.

[0018] Preferably, the donor oxide is an oxide formed of La, Y or Sm; or the donor oxide is an oxide formed of Nb or Ta;

[0019] Preferably, in the donor-doped barium titanate powder, the amount of the donor element accounts for 0.2%-0.8%.

[0020] According to another aspect of the present invention, a prepared barium titanate-based thermosensitive ceramic is provided.

[0021] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0022] (1) The present invention proposes a preparation method using donor-doped barium titanate powder as the main material and composite acceptor-doped nano-barium titanate to prepare PTC thermistor ceramics with high density and lift-to-resistance ratio; and while achieving high density and low room temperature resistance, it can achieve effective oxidation of ceramic grain boundaries, so that the thermistor ceramics have significantly improved thermal sensitivity.

[0023] (2) The two-step sintering method preferably adopted in the present invention can effectively improve the density of the fired ceramic and reduce the grain size, which is beneficial to improving the performance stability of the thermistor ceramic and facilitating the miniaturization of the multi-layer chip structure thermistor.

[0024] (3) The method of combining acceptor-doped nano-barium titanate powder with donor-doped barium titanate powder preferably adopted in the present invention can not only be used for air-sintered PTC thermistor ceramics, but also because the grain growth process is mainly achieved in the form of solid-phase grain merging nano-powders, smaller nano-powders are coated on the surface of larger solid-phase powders, and accordingly the acceptor elements therein are mainly distributed on the grain surface to form an acceptor state, which can avoid the increase of room temperature resistance.

[0025] (4) The present invention preferably adopts a method of compounding acceptor-doped nano-barium titanate powder with donor-doped barium titanate powder, wherein the compounding amount of acceptor-doped nano-barium titanate is relatively small, preferably 2wt%-15wt%, which can effectively control the cost of the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention relates to a preparation process of the high lift-to-drag ratio barium titanate-based PTC thermistor material.

[0027] Figure 2 a is the SEM image of the acceptor-doped nano-barium titanate powder prepared in Example 1. Figure 2 b is the SEM image of the thermosensitive ceramic prepared in Comparative Example 1. Figure 2 Figures c and d are SEM images of the thermosensitive ceramics of sample No. 2 and sample No. 3 in Example 1, respectively.

[0028] Figure 3 The resistance-temperature curves of the samples in Comparative Example 1 and Example 1. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0030] A method for preparing a barium titanate-based thermosensitive ceramic comprises mixing nano-barium titanate powder and donor-doped submicron barium titanate powder, forming the mixture, and then sintering the mixture to obtain the barium titanate-based thermosensitive ceramic; the nano-barium titanate powder is acceptor-doped nano-barium titanate powder or undoped nano-barium titanate powder;

[0031] The sintering is carried out at 1000° C. to 1500° C. for 0.5 to 10 hours.

[0032] In some embodiments, the present invention provides a method for preparing a high lift-to-drag ratio barium titanate-based PTC thermistor material, comprising the following steps:

[0033] (1) Preparation of acceptor-doped nano-barium titanate powder: Acceptor-doped nano-barium titanate was prepared by chemical method. Solution 1: Dissolve manganese nitrate and barium acetate in an appropriate amount of deionized water and stir until the solution is clear. Solution 2: Add tetrabutyl titanate to a mixed solution of ethanol and acetic acid and stir until the solution is clear. Solution 1 was slowly added dropwise to solution 2 and stirred continuously until the mixed solution was clear. The mixed solution was allowed to stand at 70°C for 6 hours to obtain a mixture gel, which was freeze-dried to obtain a dry gel. After grinding and calcining at 600°C-800°C for 3 hours, acceptor (manganese element)-doped nano-barium titanate powder was obtained.

[0034] Preparation of donor-doped barium titanate powder by solid-phase method: Barium carbonate, titanium dioxide, donor elements, etc. are mixed by ball milling, dried, sieved, and pre-calcined to obtain donor (such as La, Y, Sm, Nb, Ta)-doped barium titanate powder.

[0035] (2) Preparation of barium titanate-based PTC thermistor ceramics: The two barium titanate powders prepared in step (1) are mixed in an appropriate proportion by ball milling, dried, granulated, and tableted, and then sintered using a two-step method, specifically: first sintering at a high temperature of 1225°C-1425°C for 2-10 minutes, and then sintering at a low temperature of 1050°C-1200°C for 2-10 hours to obtain barium titanate-based PTC thermistor ceramics.

[0036] Preferably, the concentration of manganese nitrate in step (1) is such that manganese accounts for 0.03%-1% of the content of the prepared acceptor-doped nano-barium titanate, the concentration of barium acetate is 0.2-2 mol / L, the concentration of tetrabutyl titanate is 0.2-2 mol / L, the gelation conditions are room temperature-80°C standing for 36h-5h, the drying method is drying at 80-150°C or freeze drying, among which freeze drying is preferred, and the calcination conditions are calcination at 600°C-800°C for 2h-5h. The particle size of the prepared acceptor-doped nano-barium titanate is 10nm-80nm.

[0037] Preferably, in the donor-doped barium titanate powder, the amount of the donor element accounts for 0.2%-0.8%.

[0038] Preferably, the mixing ratio of the nanopowder in step (3) is 2wt%-15wt% of the total mass.

[0039] The following are specific embodiments

[0040] Example 1

[0041] (1) Preparation of Nano-barium Titanate Powder: Nano-barium titanate powder for composite preparation was prepared by the sol-gel method. First, manganese nitrate and barium acetate were dissolved in an appropriate amount of deionized water as solution 1, wherein the manganese ion content was 0.06 mol%, 0.2 mol%, and 0.6 mol% of the barium ion. Tetrabutyl titanate was dissolved in a 1:1 mixed solution of alcohol and acetic acid as solution 2. Solution 1 was slowly added dropwise to solution 2 while stirring. After the addition was completed, the mixed solution was placed at 70°C for 6 hours to obtain a mixture gel. After freeze-drying, a dry gel was obtained, which was crushed and calcined at 650°C to obtain acceptor-doped nano-barium titanate powder.

[0042] (2) Preparation of donor-doped barium titanate powder by solid-phase method: Barium carbonate, titanium dioxide and niobium pentoxide were mixed by ball milling with the donor content controlled to be 0.35 mol%, dried and passed through a 120 mesh sieve, and pre-calcined at 1150°C for 3 hours to obtain donor-doped barium titanate powder.

[0043] (3) Preparation of barium titanate-based PTC thermistor ceramics: 5 wt% of the acceptor-doped nanobarium titanate prepared in step (1) with 0.06 mol% Mn, 0.2 mol% Mn, and 0.6 mol% Mn was mixed with the solid-phase powder prepared in step (2) by ball milling. The mixture was then dried, sieved, granulated, tableted, and debinded. The mixture was then sintered in a mixture of N2 / H2 = 98:2 using a two-step process of holding at 1275°C for 2 minutes and at 1125°C for 4 hours. The mixture was then reoxidized at 800°C to obtain a PTC thermistor. This method achieves the purpose of doping the acceptor element to enhance the PTC effect during the reduction-reoxidation process for preparing barium titanate-based thermistor ceramics.

[0044] Figure 1 The present invention relates to a preparation process of the high lift-to-drag ratio barium titanate-based PTC thermistor material.

[0045] Comparative Example 1 (donor-doped barium titanate powder only)

[0046] (1) Preparation of donor-doped barium titanate powder by solid-phase method: Barium carbonate, titanium dioxide and niobium pentoxide were mixed by ball milling with the donor content controlled to be 0.35 mol%, dried and passed through a 120 mesh sieve, and pre-calcined at 1150°C for 3 hours to obtain donor-doped barium titanate powder.

[0047] (2) Preparation of Barium Titanate-Based PTC Thermistor Ceramics: The donor-doped powder synthesized by the solid-phase method was ball-milled, dried, sieved, granulated, pressed, and debinded. It was then sintered in a mixture of N2 / H2 = 98:2 in a two-step process of holding at 1275°C for 2 minutes and at 1125°C for 4 hours. The powder was then reoxidized at 800°C to obtain a PTC thermistor. This method achieves the purpose of enhancing the PTC effect by doping acceptor elements in the reduction-reoxidation process for preparing barium titanate-based thermistor ceramics.

[0048] Figure 2 Reference a is a SEM image of the acceptor-doped nano-barium titanate powder prepared in Example 1. It can be seen that the particle size of the prepared acceptor-doped nano-barium titanate is about 30 nm-50 nm, which meets the requirements. Figure 2 b is the SEM image of the thermosensitive ceramic prepared in Comparative Example 1. Figure 2 The SEM images of the thermosensitive ceramics of sample No. 2 and sample No. 3 in Example 1 are shown in Figures c and d, respectively. Figure 2 It can be seen that with the addition of acceptor-doped nano-barium titanate, the ceramic grains did not show abnormal growth, the microscopic porosity of the ceramic was reduced, and the density was increased.

[0049] Figure 3 The resistance-temperature curves of the samples in Comparative Example 1 and Example 1.

[0050] Table 1 below shows the temperature resistance properties of the thermosensitive ceramics prepared in Example 1 and Comparative Example 1.

[0051] Table 1

[0052]

[0053] from Figure 3 As can be seen from Table 1, the sample in Comparative Example 1 exhibits a lower room temperature resistance, which is due to the two-step sintering process that makes the sample have a higher density and a higher degree of semiconductivity. However, due to the high density, the reoxidation of the sample is difficult, so its R max With the addition of acceptor-doped nano-barium titanate, the room temperature resistance R min The change is small, while the reoxidation process is significantly improved. max The increase is more than two orders of magnitude, accompanied by a significant increase in the lift-to-drag ratio. As the Mn content in the acceptor-doped nano-barium titanate gradually increases, the room temperature resistance R min Still low, while R max When the Mn content increases to about 0.6 mol%, the room temperature resistance increases significantly. max The lift-to-drag ratio is improved, but the lift-to-drag ratio is reduced.

[0054] Example 2

[0055] The overall steps are the same as those in Example 1, except that the sintering method used in step (3) is changed to air sintering. The two-step sintering method is a high-temperature 1325°C holding time of 2 minutes and a low-temperature 1175°C holding time of 4 hours, and no reoxidation in air is required. The temperature resistance properties of the prepared thermistor ceramic are shown in Table 2 below:

[0056] Table 2

[0057]

[0058] As can be seen in Table 2, the room temperature resistance of the air-sintered thermosensitive ceramics begins to slowly increase with the incorporation of acceptor-doped nanobarium titanate, reaching a significant increase at a manganese content of 0.6 mol%. This gradual increase in the lift-to-resistance ratio indicates that the preparation method of composite acceptor-doped nanobarium titanate, using solid-phase synthesis powder as the main raw material, is also suitable for air sintering.

[0059] Example 3

[0060] The overall steps are the same as those in Example 1, except that the 0.06 mol% Mn acceptor-doped nano-barium titanate is added in step (3) in an amount of 10 wt% and 15 wt%. The temperature resistance properties of the prepared thermosensitive ceramics are shown in Table 3 below:

[0061] Table 3

[0062] Sample number sample <![CDATA[R min / Oh]]> <![CDATA[R max / Oh]]> lift-to-drag ratio 9 10wt% nano-barium titanate 12.76 <![CDATA[3.26×10 6 ]]> <![CDATA[2.56×10 5 ]]> 10 15wt% nano-barium titanate 48.04 <![CDATA[2.25×10 7 ]]> <![CDATA[4.68×10 5 ]]>

[0063] From Table 3, we can see that as the amount of nano-barium titanate added increases, its room temperature resistance also increases significantly, and its maximum resistance R max The increase is faster, accompanied by a further increase in the lift-to-drag ratio.

[0064] Example 4

[0065] The overall steps are the same as those in Example 1, except that the acceptor doping in step (1) is changed to ferric nitrate, with the contents being 0.06 mol% Fe, 0.2 mol% Fe, and 0.6 mol% Fe. The temperature resistance properties of the prepared thermistor ceramics are shown in Table 4 below:

[0066] Table 4

[0067] Sample number sample <![CDATA[R min / Oh]]> <![CDATA[R max / Oh]]> lift-to-drag ratio 11 0.06mol%Fe 12.50 <![CDATA[1.6×10 6 ]]> <![CDATA[1.28×10 5 ]]> 12 0.2 mol% Fe 60.42 <![CDATA[1.1×10 7 ]]> <![CDATA[1.8×10 5 ]]> 13 0.6 mol% Fe 225.3 <![CDATA[1.3×10 7 ]]> <![CDATA[5.8×10 4 ]]>

[0068] As can be seen from Table 4, when Fe element is added to nano-barium titanate as an acceptor and then mixed with donor-doped barium titanate to prepare PTC ceramics, its room temperature resistance increases, and its lift-to-resistance ratio is also significantly improved compared with Comparative Example 1 in Example 1, indicating an enhancement of the PTC effect.

[0069] Example 5

[0070] (1) Preparation of nano-barium titanate powder: Nano-barium titanate powder for composite is prepared by hydrothermal method. First, manganese nitrate and barium acetate are dissolved in an appropriate amount of deionized water as solution 1, wherein the manganese ion content is 0.06 mol%, 0.2 mol%, and 0.6 mol% of the barium ion; tetrabutyl titanate is dissolved in an alcohol solution as solution 2. During the stirring process, solution 1 is slowly added dropwise to solution 2, and ammonia water is added dropwise to make the pH value of the solution higher than 10 to obtain a mixed solution. The mixture is placed in a high-pressure hydrothermal autoclave for hydrothermal reaction at a temperature of 180°C and a time of 12 hours.

[0071] The obtained powder is then repeatedly washed with deionized water and / or ethanol and dried to obtain acceptor-doped nano-barium titanate powder.

[0072] (2) Barium carbonate, titanium dioxide and niobium pentoxide were mixed by ball milling using a solid phase method, with the donor content controlled to be 0.35 mol%, dried and passed through a 120 mesh sieve, and pre-calcined at 1150° C. for 3 hours to obtain donor-doped barium titanate powder.

[0073] (3) Preparation of barium titanate-based PTC thermistor ceramics: 5 wt% of the acceptor-doped nanobarium titanate prepared in step (1) with 0.06 mol% Mn, 0.2 mol% Mn, and 0.6 mol% Mn was mixed with the solid-phase powder prepared in step (2) by ball milling. The mixture was then dried, sieved, granulated, tableted, and debinded. The mixture was then sintered in a mixture of N2 / H2 = 98:2 using a two-step process of holding at 1275°C for 2 minutes and at 1125°C for 4 hours. The mixture was then reoxidized at 800°C to obtain a PTC thermistor. This method achieves the purpose of doping the acceptor element to enhance the PTC effect during the reduction-reoxidation process for preparing barium titanate-based thermistor ceramics.

[0074] Table 5 below shows the temperature resistance properties of the prepared thermistor ceramics:

[0075] Table 5

[0076]

[0077] As can be seen from Table 5, the PTC thermistor ceramics prepared by using a hydrothermal method instead of a sol-gel method to prepare acceptor-doped nano-barium titanate and mixing it with donor-doped barium titanate also maintain a low room temperature resistance compared to Comparative Example 1 in Example 1, and the lift-to-drag ratio also shows a significant improvement.

[0078] Example 6

[0079] (1) Preparation of Nano-barium Titanate Powder: Nano-barium titanate powder for composite preparation was prepared by the sol-gel method. First, barium acetate was dissolved in an appropriate amount of deionized water as solution 1; tetrabutyl titanate was dissolved in a 1:1 mixture of alcohol and acetic acid as solution 2. Solution 1 was slowly added dropwise to solution 2 while stirring. After the addition was complete, the mixture was placed at 70°C for 6 hours to obtain a mixture gel. After freeze-drying, the dry gel was obtained, which was crushed and calcined at 650°C to obtain acceptor-doped nano-barium titanate powder.

[0080] (2) Preparation of donor-doped barium titanate powder by solid-phase method: Barium carbonate, titanium dioxide and niobium pentoxide were mixed by ball milling with the donor content controlled to be 0.35 mol%, dried and passed through a 120 mesh sieve, and pre-calcined at 1150°C for 3 hours to obtain donor-doped barium titanate powder.

[0081] (3) Preparation of barium titanate-based PTC thermistor ceramics: The nano-barium titanate prepared in step (1) was mixed with the solid-phase powder prepared in step (2) by ball milling at 5 wt%, dried, sieved, granulated, tableted, and debinded. The mixture was then sintered in a mixture of N2 / H2 = 98:2 using a two-step method of holding at 1275°C for 2 minutes and at 1125°C for 4 hours. The mixture was then reoxidized at 800°C to obtain a PTC thermistor. This method achieves the purpose of doping acceptor elements to enhance the PTC effect during the reduction-reoxidation process for preparing barium titanate-based thermistor ceramics.

[0082] Table 6

[0083] Sample number sample <![CDATA[R min / Oh]]> <![CDATA[R max / Oh]]> lift-to-drag ratio 14 Nano-barium titanate 6.13 <![CDATA[2.47×10 5 ]]> <![CDATA[4.02×10 4 ]]>

[0084] As can be seen from Table 6, the PTC thermistor ceramic prepared by adding undoped nano-barium titanate to the barium titanate powder prepared by the solid-phase method also shows a significant improvement in lift-to-drag ratio compared to Comparative Example 1 in Example 1. The undoped nano-barium titanate promotes grain boundary oxidation of the barium titanate ceramic and enhances the PTC thermistor effect.

[0085] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing barium titanate-based thermal ceramics, characterized in that: The nano-barium titanate powder and the donor-doped submicron barium titanate powder are mixed and formed, and then sintered to obtain the barium titanate-based thermosensitive ceramic; the nano-barium titanate powder is acceptor-doped nano-barium titanate powder or undoped nano-barium titanate powder; The sintering is carried out at 1000° C.-1500° C. for 0.5 h-10 h.

2. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The acceptor element in the acceptor-doped nano-barium titanate powder is manganese or iron; Preferably, the amount of the acceptor element in the acceptor-doped nano-barium titanate powder accounts for 0.03%-1%.

3. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The particle size of the acceptor-doped nano-barium titanate powder is 10nm-80nm.

4. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The mass of the nano-barium titanate powder accounts for 2%-15% of the sum of the mass of the nano-barium titanate powder and the donor-doped submicron barium titanate powder.

5. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The sintering is a two-step sintering process, specifically: first sintering at 1225° C.-1425° C. for 2-10 minutes, and then sintering at 1050° C.-1200° C. for 2-10 hours.

6. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The preparation method of the acceptor-doped nano-barium titanate powder is specifically as follows: A compound containing an acceptor element and a barium salt are dissolved in water to obtain a first solution; a titanium salt is added to a mixed solvent of ethanol and acetic acid to obtain a second solution; the first solution is added dropwise to the second solution to obtain a mixed solution; the mixed solution is allowed to stand to obtain a mixture gel; the mixture is freeze-dried to obtain a xerogel; the xerogel is ground and calcined to obtain acceptor-doped nano-barium titanate powder; Alternatively, a compound containing an acceptor element and a barium salt are dissolved in water to obtain a first solution, and the titanium salt is added to a mixed solvent of ethanol and acetic acid to obtain a second solution; adding the first solution dropwise to the second solution to obtain a mixed solution; subjecting the mixed solution to a hydrothermal reaction to obtain acceptor-doped nano-barium titanate powder; Preferably, when the acceptor element is manganese, the compound containing the acceptor element is manganese nitrate; when the acceptor element is iron, the compound containing the acceptor element is ferric chloride or ferric nitrate.

7. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 6, wherein: The dry gel is ground and calcined at 600-800° C. for 2-5 hours; the temperature of the hydrothermal reaction is 160-220° C., and the time is 4-20 hours.

8. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 1, wherein: The preparation method of the donor-doped submicron barium titanate powder is specifically as follows: barium carbonate, titanium dioxide and donor oxide are ball-milled and mixed, and then calcined at 1000-1200°C for 2-3 hours to obtain donor-doped submicron barium titanate powder with a size of 0.1 μm-1 μm.

9. The method for preparing the barium titanate-based thermosensitive ceramic according to claim 8, wherein: The donor oxide is an oxide formed by La, Y or Sm; or the donor oxide is an oxide formed by Nb or Ta; Preferably, in the donor-doped barium titanate powder, the amount of the donor element accounts for 0.2%-0.8%.

10. The barium titanate-based thermal-sensitive ceramic prepared by the method according to any one of claims 1 to 9.

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