Preparation method of barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic

Abstract

The application discloses a preparation method of a barium strontium titanate-based solid solution system negative temperature coefficient thermosensitive ceramic, and the preparation method comprises the following steps: taking bismuth oxide, zinc oxide, titanium oxide, barium carbonate and strontium carbonate as raw materials, mixing, grinding, calcining, cold isostatic pressing, high-temperature sintering and electrode coating of the bismuth oxide, the zinc oxide, the titanium oxide, the barium carbonate and the strontium carbonate by using a traditional solid phase method to prepare xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 solid solution system negative temperature coefficient thermosensitive ceramic. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 thermosensitive material, and the electrical properties of the material can be accurately adjusted by regulating the molar ratio of the chemical formula, a novel thermosensitive material having obvious negative temperature coefficient characteristics in the range of 400-1000 DEG C is successfully synthesized, and the novel thermosensitive material can be applied to the fields of temperature measurement, temperature control and electronic component protection.

Description

Technical Field

[0001] This invention relates to a novel high-temperature thermistor material, specifically to a method for preparing a negative temperature coefficient thermistor ceramic based on a barium strontium titanate solid solution system. Background Technology

[0002] With the rapid development of high-tech fields such as automobiles, communications, and electronics, the requirements for intelligent, multifunctional, and miniaturized temperature sensors are constantly increasing. Negative temperature coefficient thermistors are materials whose resistance decreases exponentially with increasing temperature. Their excellent sensitivity allows them to detect extremely small temperature changes, making them ideal temperature sensor materials. Thermistors used at temperatures above 300℃ are generally considered high-temperature thermistors, which are ideal replacements for precious metal sensors used in industry and have broad prospects. However, traditional spinel-type transition metal oxide thermistors often exhibit severe aging when used at high temperatures, failing to achieve accurate temperature measurements. Therefore, developing new material systems has become a current research hotspot.

[0003] In recent years, perovskite (ABO3) materials have been widely used in piezoelectric, ferroelectric, and dielectric fields. Among them, barium strontium titanate is a composite perovskite material with A-site ions substituted, while zinc bismuth titanate is a composite perovskite material with B-site ions substituted. Their unique perovskite structure makes them more stable than spinel structures, with fewer voids in the crystal structure. Perovskite materials exhibit excellent performance in the high-temperature range (x≥300℃) due to their high sensitivity and good stability. Furthermore, by adding a second component to form a multi-component composite solid solution, the perovskite structure Ba... 0.5 Sr 0.5 While using TiO3, the electrical properties can also be optimized by utilizing the recombination effect, and the introduced BiZn 0.5 Ti 0.5 O3 is the second component and Ba 0.5 Sr 0.5 TiO3 was composited to prepare perovskite solid solution ceramic materials with excellent performance and stable structure. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution system.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution includes the following steps:

[0007] a. According to xBiZn 0.5 Ti 0.5O3-(1-x)Ba 0.5 Sr 0.5 The composition is TiO3, where 0.05≤x≤0.95. Bismuth oxide, zinc oxide, titanium oxide, barium carbonate, and strontium carbonate are weighed and mixed. The mixed raw materials are then ground to obtain a powder material.

[0008] b. Calcine the ground powder material to obtain xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder;

[0009] c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder is pressed into blocks to obtain bulk materials, and then the bulk materials are subjected to cold isostatic pressing.

[0010] d. The thermistor material is obtained by high-temperature sintering of bulk material;

[0011] e. Coat the front and back sides of the thermistor material with platinum paste electrodes and anneal to obtain thermistor material with a temperature range of 400-1000℃.

[0012] In step a, the mixed raw materials are ground in an agate mortar for 4-12 hours to obtain powder material.

[0013] In step b, the ground powder material is calcined at 700-1000℃ for 3-6 hours to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder.

[0014] In step c, xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder at 15-30 kg / cm³ 2 The material is pressed into blocks under pressure for 1-3 minutes to obtain a block material. The block material is then subjected to cold isostatic pressing at a pressure of 200-350MPa for 180 seconds.

[0015] In step d, the bulk material is placed in a bell furnace and sintered at a temperature of 1150-1350℃ for 2-5 hours to obtain the thermistor material.

[0016] In step e, the annealing temperature is 835℃ and the time is 30 min. The material constant of the obtained thermistor material is B. 400℃ / 800℃ =12374-13469K, resistivity ρ 800℃ It is 6290-18378 Ω·cm.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a method for preparing a negative temperature coefficient thermistor ceramic based on a barium strontium titanate solid solution system. Using bismuth oxide, zinc oxide, titanium oxide, barium carbonate, and strontium carbonate as raw materials, the method employs a traditional solid-state method to mix, grind, calcine, cold isostatically press, sinter at high temperature, and coat electrodes to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 solid solution system negative temperature coefficient thermistor ceramic, where 0.05≤x≤0.95, allows for precise adjustment of the resistivity ρ and material constant B by controlling the molar ratio of the general chemical formula. Its electrical performance parameters are: B 400℃ / 800℃ =12374-13469K, resistivity ρ 800℃ The Ω·cm value ranges from 6290 to 18378. The thermistor material obtained by this method exhibits a significant negative temperature coefficient in the temperature range of 400-1000℃, making it a novel thermistor material suitable for preparing high-temperature thermistors. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The image shows the XRD pattern of the thermistor material obtained in Example 1 of this invention.

[0020] Figure 2 This is a resistance-temperature characteristic curve of the thermistor material obtained in Example 1 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be 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 illustrative and not intended to limit the invention.

[0022] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0023] Example 1

[0024] This embodiment provides a method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution, including the following steps:

[0025] a. According to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 The composition is TiO3, where x = 0.05. Bismuth oxide, zinc oxide, titanium oxide, barium carbonate and strontium carbonate are weighed and mixed. The mixed raw materials are placed in an agate mortar and ground for 4 hours to obtain powder material.

[0026] b. Calcine the ground powder material at 1000℃ for 6 hours to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder;

[0027] c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder at 15kg / cm 2 The material is pressed into blocks under pressure for 3 minutes to obtain a block material. The block material is then subjected to cold isostatic pressing at a pressure of 350 MPa for 180 seconds.

[0028] d. Place the bulk material in a bell furnace and sinter at 1350℃ for 2 hours to obtain the thermistor material;

[0029] e. Coat both sides of the thermistor material with platinum paste electrodes, then anneal at 835℃ for 30 minutes to obtain a thermistor material with a temperature range of 400-1000℃ and a material constant of B. 400℃ / 800℃ =12374K, resistivity ρ 800℃ It is 6290 Ω·cm.

[0030] This method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution uses bismuth oxide, zinc oxide, titanium oxide, barium carbonate, and strontium carbonate as raw materials. The traditional solid-state method involves mixing, grinding, calcining, cold isostatic pressing, high-temperature sintering, and electrode coating of bismuth oxide, zinc oxide, titanium oxide, barium carbonate, and strontium carbonate to prepare xBiZn. 0.5 Ti 0.5O3-(1-x)Ba 0.5 Sr 0.5 TiO3 solid solution system negative temperature coefficient thermistor ceramic, its electrical properties were tested, combined with Figure 1 , Figure 2 As shown, the results indicate that the temperature and resistance of this material exhibit a good linear relationship in the high-temperature region of 400-1000℃, and it can be used to make high-temperature negative temperature coefficient thermistors.

[0031] Example 2

[0032] This embodiment provides a method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution, including the following steps:

[0033] a. According to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 The composition is TiO3, where x = 0.2. Bismuth oxide, zinc oxide, titanium oxide, barium carbonate and strontium carbonate are weighed and mixed. The mixed raw materials are placed in an agate mortar and ground for 6 hours to obtain powder material.

[0034] b. Calcine the ground powder material at 800℃ for 4 hours to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder;

[0035] c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder at 20 kg / cm 2 The material is pressed into blocks under pressure for 1.5 minutes to obtain a block material. The block material is then subjected to cold isostatic pressing at a pressure of 250 MPa for 180 seconds.

[0036] d. Place the bulk material in a bell furnace and sinter at 1250℃ for 3 hours to obtain the thermistor material;

[0037] e. Coat both sides of the thermistor material with platinum paste electrodes, then anneal at 835℃ for 30 minutes to obtain a thermistor material with a temperature range of 400-1000℃ and a material constant of B. 400℃ / 800℃ =12512K, resistivity ρ 800℃ It is 9491 Ω·cm.

[0038] Example 3

[0039] This embodiment provides a method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution, including the following steps:

[0040] a. According to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 The composition is TiO3, where x = 0.6. The raw materials bismuth oxide, zinc oxide, titanium oxide, barium carbonate and strontium carbonate are weighed and mixed. The mixed raw materials are placed in an agate mortar and ground for 10 hours to obtain powder material.

[0041] b. Calcine the ground powder material at 900℃ for 5 hours to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder;

[0042] c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder at 25 kg / cm 2 The material is pressed into blocks under pressure for 2.5 minutes to obtain a block material. The block material is then subjected to cold isostatic pressing at a pressure of 300 MPa for 180 seconds.

[0043] d. Place the bulk material in a bell furnace and sinter at 1300℃ for 4 hours to obtain the thermistor material;

[0044] e. Coat both sides of the thermistor material with platinum paste electrodes, then anneal at 835℃ for 30 minutes to obtain a thermistor material with a temperature range of 400-1000℃ and a material constant of B. 400℃ / 800℃ =13028K, resistivity ρ 800℃ It is 15344 Ω·cm.

[0045] Example 4

[0046] This embodiment provides a method for preparing negative temperature coefficient thermistor ceramics based on barium strontium titanate solid solution, including the following steps:

[0047] a. According to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5The composition is TiO3, where x = 0.95. Bismuth oxide, zinc oxide, titanium oxide, barium carbonate and strontium carbonate are weighed and mixed. The mixed raw materials are placed in an agate mortar and ground for 12 hours to obtain powder material.

[0048] b. Calcine the ground powder material at 700℃ for 3 hours to obtain xBiZn. 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder;

[0049] c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder at 30 kg / cm 2 The material is pressed into blocks under pressure for 1 minute to obtain a block material. The block material is then subjected to cold isostatic pressing at a pressure of 200 MPa for 180 seconds.

[0050] d. Place the bulk material in a bell furnace and sinter at 1150℃ for 5 hours to obtain the thermistor material;

[0051] e. Coat both sides of the thermistor material with platinum paste electrodes, then anneal at 835℃ for 30 minutes to obtain a thermistor material with a temperature range of 400-1000℃ and a material constant of B. 400℃ / 800℃ =13469K, resistivity ρ 800℃ It is 18378 Ω·cm.

[0052] In summary, this invention relates to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 Starting from the semiconducting properties of TiO3 thermistor, the electrical properties of the material can be precisely adjusted by controlling the chemical formula molar ratio. A novel thermistor material with a significant negative temperature coefficient in the range of 400-1000℃ has been successfully synthesized, which can be applied to temperature measurement, temperature control and electronic component protection.

[0053] The above are merely preferred embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A method for preparing a barium strontium titanate-based solid solution system negative temperature coefficient thermosensitive ceramic, characterized in that, The method comprises the following steps: a, according to xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 composition, wherein 0.05≤x≤0.95, respectively, the raw material bismuth oxide, zinc oxide, titanium oxide, barium carbonate, strontium carbonate mixed, the mixed raw material grinding, get powder material; b. calcining the ground powder material to obtain xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder; c. xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder compacting to obtain bulk material, and then cold isostatic pressing the bulk material; d. sintering the bulk material at high temperature to obtain a thermistor material; e. coating the thermistor material with platinum paste electrodes on both sides, and annealing to obtain a thermistor material with a temperature range of 400-1000℃.

2. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, In step a, the mixed raw materials are ground in an agate mortar for 4-12h to obtain a powder material.

3. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, In step b, the ground powder material is calcined at a temperature of 700-1000°C for 3-6h to obtain xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3powder.

4. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, In step c, xBiZn 0.5 Ti 0.5 O3-(1-x)Ba 0.5 Sr 0.5 TiO3 powder is briquetted at a pressure of 15-30 kg / cm 2 for 1-3 min to obtain a block material, and the block material is cold isostatic pressed at a pressure of 200-350 MPa for 180 s.

5. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, In step d, the bulk material is sintered in a bell jar furnace at a temperature of 1150-1350℃ for 2-5h to obtain the thermistor material.

6. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, In step e, the annealing temperature is 835℃, and the time is 30min.

7. The method for preparing a barium strontium titanate-based solid solution negative temperature coefficient thermosensitive ceramic according to claim 1, characterized in that, The material constant of the obtained thermistor material in step e is B 400℃ / 800℃ = 12374 - 13469 K, and the resistivity p 800℃ is 6290 - 18378 Ω-cm.

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