Nd-doped non-cooled infrared detector and preparation method of magneto-sensitive nickelate ceramic

Abstract

The application discloses a preparation method of a Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity, and relates to the technical field of functional ceramic preparation.The application comprises the following stages: solution preparation, wet gel process, dry gel process, calcination process, powder pressing process and secondary calcination process.The application uses a sol-gel method to prepare a series of nickelate ceramic target materials with high density, good crystallization quality, short preparation period and excellent performance, and the nickelate ceramic target materials have the application conditions of uncooled and low noise, the characteristics of high sensitivity and low room temperature resistivity without toxicity and pollution, and can be used as candidate materials of uncooled infrared detectors and magnetic sensitive devices with higher possibility of military and high-end devices.

Description

Technical Field

[0001] This invention relates to an Nd-doped uncooled infrared detector and a method for preparing nickelate ceramics for magnetic sensitivity, belonging to the field of functional ceramics preparation technology. Background Technology

[0002] With the continuous development of science and technology, the research and development of new materials has become one of the hot topics in the field of materials science. Infrared detection technology has important application value in military, security, and medical fields. However, traditional cooled infrared detection technology suffers from problems such as high cost, high energy consumption, and bulky size, which limits its promotion in practical applications. Uncooled technology can reduce costs and improve portability, bringing new opportunities and challenges to the application of infrared detection technology. Therefore, the development of uncooled infrared detection thermistor materials is one of the key factors driving the continuous progress and application expansion of infrared detection technology. From VO x From traditional materials such as amorphous silicon (a-Si) to novel materials such as carbon nanotubes (CNTs) and a few metal oxides, researchers have paid particular attention to their sensitivity, response speed, and performance parameters. However, the selection of such materials is mainly based on factors such as temperature coefficient of resistance (TCR), resistance value, and noise characteristics. Currently available uncooled infrared detectors struggle to maintain high sensitivity under extreme temperature and room temperature conditions, which significantly limits their applications. Therefore, designing and fabricating a thermistor material with low resistivity and high TCR over a wide temperature range is urgently needed to address these issues.

[0003] Nickels with the general formula A2BO4 and a K2NiF4-type structure exhibit very attractive and versatile physical properties, such as superconductivity, magnetoresistance, mixed ionic and electronic conductivity, giant dielectric, low-loss microwave dielectric, and thermoelectricity, showing great promise for applications in many energy and electronic device fields. Possible reasons for these various properties include coordination polyhedral distortion, charge polarization, and polaron conductivity mechanisms. Since most of these oxides contain many variable-valence elements and possess high conductivity, their transport properties have been extensively studied. Currently, common methods for preparing nickelates include solid-state reaction, sol-gel, and co-precipitation methods. The sol-gel method is a relatively mature method for preparing ceramic targets, producing samples with high purity and uniform dispersion, low preparation cost, and short preparation cycle, suitable for mass production. Therefore, this invention addresses the above-mentioned problems by proposing the use of the sol-gel method to prepare an Nd-doped Pr2NiO4 ceramic target, obtaining a non-toxic, pollution-free, high-density, low-resistivity, and wide-temperature-range high-TCR sensitive uncooled detector storage material. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing Nd-doped uncooled infrared detectors and nickelate ceramics for magnetic sensitivity. The method produces ceramic targets with excellent comprehensive performance, including low resistivity, high sensitivity, and room temperature range, which can be used as candidate materials for uncooled infrared detectors.

[0005] The method for preparing the Nd-doped uncooled infrared detector and the magnetically sensitive nickelate ceramic of the present invention is characterized by the following steps:

[0006] (1) Solution preparation: Weigh all raw materials, including praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid, according to the stoichiometric ratio. Use aqueous solution as a carrier for the mixed raw materials, citric acid as a chelating agent, and an appropriate amount of ethylene glycol as a dispersant.

[0007] (2) Wet gelation process: The mixed solution in step (1) is stirred and reacted in a constant temperature magnetic stirrer, and the temperature is set to about 95°C;

[0008] (3) Dry gel process: The wet gel obtained in step (2) is placed in an oven to continue foaming. After the foaming is complete, it is dried to finally obtain a dry gel without precipitation.

[0009] (4) Calcination process: The dry gel obtained in step (3) is ground into fine and uniform powder in an agate mortar for about 0.5 hours, and then calcined in air atmosphere.

[0010] (5) Powder pressing process: After the powder from step (4) is fully ground again, it is pressed into blocks by an automatic tablet press;

[0011] (6) Secondary calcination process: calcining the block material obtained in step (5) in an air atmosphere.

[0012] Furthermore, in step (1), the measurement error is controlled within ±0.0005g, all raw materials have a purity of AR, and the chemical formula of the prepared compound is Pr. 2-x Nd x NiO4, where 0 ≤ x ≤ 0.4.

[0013] Furthermore, the gelation time in step (2) is about 1 hour. No precipitate is formed after gelation. The stirring speed is slowed down during the process of the mixed solution changing from a clear blue state to a foamy, yellow-smoking wet gel until it becomes a foamy wet gel state.

[0014] Further, in step (3), the oven temperature is set to 140℃, and the drying time is 8-12 hours under normal pressure and air atmosphere.

[0015] Furthermore, the grinding time in step (4) is about 0.5 hours, and the calcination is carried out in an air atmosphere at a temperature of 400-800℃ with a heating rate of 1-5℃ / min.

[0016] Furthermore, in step (5), the precursor powder grinding time after one calcination is about 0.5h, the mold size is 20mm, the automatic tablet press is set to 5-6Mpa, and the time is about 20min.

[0017] Furthermore, the secondary calcination temperature in step (6) is 1200-1500℃.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The Pr prepared by the sol-gel method in this invention 2-x Nd x NiO4 ceramic targets have high density, uniform composition and particle size distribution, stable preparation process and performance, and are non-toxic, non-polluting, easy to repeat, and have a short preparation cycle, making them suitable for mass production.

[0020] (2) The ceramic samples of this invention exhibit low resistivity (<100 Ω·cm) in the temperature range of 150-350 K, displaying typical characteristics of an insulator and a negative temperature coefficient thermistor. The optimal room temperature resistivity reaches 0.06 Ω·cm. The highest room temperature TCR reaches -4.43 %·K. -1 It can maintain -4% K under ambient conditions at room temperature and near room temperature. -1 Compared with other NTC materials, it has a relative performance advantage. Attached Figure Description

[0021] Figure 1 The XRD diffraction pattern of the Nd-doped uncooled infrared detector and the nickelate ceramic for magnetic sensitivity described in this invention;

[0022] Figure 2 The image shows the SEM image of the Pr2NiO4 ceramic target obtained in Example 1 of this invention.

[0023] Figure 3 The resistance-temperature measurement curve of the Pr2NiO4 ceramic target obtained in Example 1 of this invention;

[0024] Figure 4 The TCR-T measurement curve of the Pr2NiO4 ceramic target obtained in Example 1 of this invention;

[0025] Figure 5 The Pr obtained in Embodiment 2 of the present invention 1.9 Ni 0.1 Resistance-temperature measurement curve of O4 ceramic target;

[0026] Figure 6 The Pr obtained in Embodiment 2 of the present invention 1.9 Ni 0.1 TCR-T measurement curve of O4 ceramic target;

[0027] Figure 7 The Pr obtained in Embodiment 3 of the present invention 1.8 Ni 0.2 Resistance-temperature measurement curve of O4 ceramic target;

[0028] Figure 8 The Pr obtained in Embodiment 3 of the present invention 1.8 Ni 0.2 TCR-T measurement curve of O4 ceramic target;

[0029] Figure 9 The Pr obtained in Example 4 of this invention 1.7 Ni 0.3 Resistance-temperature measurement curve of O4 ceramic target;

[0030] Figure 10 The Pr obtained in Example 4 of this invention 1.7 Ni 0.3 TCR-T measurement curve of O4 ceramic target;

[0031] Figure 11 The Pr obtained in Embodiment 5 of the present invention 1.6 Ni 0.4 SEM images of O4 ceramic target material;

[0032] Figure 12 The Pr obtained in Embodiment 5 of the present invention 1.6 Ni 0.4 Resistance-temperature measurement curve of O4 ceramic target;

[0033] Figure 13 The Pr obtained in Embodiment 5 of the present invention 1.6 Ni 0.4 TCR-T measurement curve of O4 ceramic target; Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Example 1

[0036] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0037] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, the weighing error of raw materials is controlled within ±0.0005g, aqueous solution is used as carrier of mixed raw materials, citric acid is used as chelating agent, and appropriate amount of ethylene glycol is used as dispersant.

[0038] (2) Wet gel process: Place the mixed solution of step (1) in a 95℃ constant temperature magnetic stirrer and stir for 1 hour. During the process of the mixed solution changing from a blue transparent state to a foaming and yellow smoke wet gel, the stirring speed is slowed down until it becomes a foaming wet gel state.

[0039] (3) Dry gel process: The wet gel obtained in step (2) is placed in a constant temperature oven for continued foaming. The drying temperature is 140℃ and the time is 8-12h. After the foaming is complete, it is fully dried to finally obtain a dry gel without precipitation.

[0040] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar for about 0.5 hours. Then, it is calcined once in an air atmosphere for 8 hours at a calcination temperature of 600℃ (400-800℃).

[0041] (5) Powder pressing process: After grinding the powder from step (4) again for 0.5h, press it into a block shape under an automatic tablet press. The mold size is 20mm, the automatic tablet press is set to 5-6MPa, and the time is 20min.

[0042] (6) Secondary calcination process: The blocks obtained in step (5) are calcined in air for 12 hours at a temperature of 1350℃ (1200-1500℃).

[0043] The Nd-doped uncooled infrared detector and the magnetically sensitive nickelate ceramic obtained in Example 1 are, through... Figure 2 SEM images showed good crystal quality and a dense surface. The room temperature resistivity was 0.13 Ω·cm, and the room temperature TCR reached -3.4%·K. -1 .

[0044] Example 2

[0045] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0046] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0.1) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, use aqueous solution as carrier of mixed raw materials, use citric acid as chelating agent, and use appropriate amount of ethylene glycol as dispersant;

[0047] (2) Wet gel process: The mixed solution in step (1) is stirred and reacted at 95°C in a constant temperature magnetic stirrer. The mixed solution changes from a clear blue state to a foaming wet gel that emits yellow smoke.

[0048] (3) Dry gel process: The wet gel obtained in step (2) is placed in an oven to continue foaming. After the foaming is complete, it is dried to obtain a loose dry gel without precipitation.

[0049] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar for 0.5 hours, and then calcined in air.

[0050] (5) Powder pressing process: After the powder from step (4) is fully ground again, it is pressed into blocks by an automatic tablet press;

[0051] (6) Secondary calcination process: The block material obtained in step (5) is calcined for a second time in air atmosphere. The calcination holding time is 12h and the calcination temperature is 1350℃.

[0052] The Nd-doped uncooled infrared detector and Pr magnetic sensitizer obtained in Example 2 1.9 Nd 0.1 NiO4 nickelate ceramics, through Figure 5 and 6 The room temperature resistivity shows an increasing trend, reaching 0.42 Ω·cm, and the room temperature TCR reaches -4.43%·K. -1 .

[0053] Example 3

[0054] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0055] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0.2) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, use aqueous solution as solvent, and use citric acid and ethylene glycol as chelating agent and dispersant respectively in the preparation;

[0056] (2) Wet gel process: The mixed solution in step (1) is stirred and reacted thoroughly in a magnetic stirrer. The mixed solution changes from a clear blue state to a foaming wet gel that emits yellow smoke.

[0057] (3) Dry gel process: The wet gel obtained in step (2) is placed in a 140℃ oven for rapid foaming. After complete foaming, it is dried for 8-12 hours to finally obtain a loose dry gel without precipitation.

[0058] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar for 0.5 hours, and then calcined in air.

[0059] (5) Powder pressing process: After the powder from step (4) is fully ground again, it is pressed into blocks by an automatic tablet press;

[0060] (6) Secondary calcination process: The block material obtained in step (5) is calcined for a second time in air atmosphere. The calcination holding time is 12h and the calcination temperature is 1350℃.

[0061] The Nd-doped uncooled infrared detector and Pr magnetic sensitizer obtained in Example 3 of this embodiment 1.8 Nd 0.2 NiO4 nickelate ceramics, through Figure 7 and 8 The resistivity at 300K is 0.13 Ω·cm, and the TCR is -3.44%·K. -1 Within the tested temperature range, the TCR reached a maximum of -7.13% K. -1 The corresponding temperature is 337.5K, which provides good applicable conditions for the sensitivity and response speed of uncooled infrared detectors.

[0062] Example 4

[0063] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0064] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0.3) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, use aqueous solution as solvent, and use citric acid and ethylene glycol as chelating agent and dispersant respectively in preparation;

[0065] (2) Wet gel process: The mixed solution in step (1) is stirred and reacted thoroughly in a magnetic stirrer. The mixed solution changes from a clear blue state to a foaming wet gel that emits yellow smoke.

[0066] (3) Dry gel process: The wet gel obtained in step (2) is placed in a constant temperature oven at 140℃ for rapid foaming. After complete foaming, it is dried for 8-12 hours to finally obtain a loose dry gel without precipitation.

[0067] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar and then calcined in an air atmosphere.

[0068] (5) Powder pressing process: After the powder from step (4) is fully ground again, it is pressed into blocks by an automatic tablet press;

[0069] (6) Secondary calcination process: The block material obtained in step (5) is calcined a second time in an air atmosphere.

[0070] The Nd-doped uncooled infrared detector and Pr magnetic sensitizer obtained in Example 4 of this embodiment 1.7 Nd 0.3 NiO4 nickelate ceramics, through Figure 9 and 10 The resistivity at 300K is 0.17 Ω·cm, and the TCR is -4.29%·K. -1 .

[0071] Example 5

[0072] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0073] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0.4) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, use aqueous solution as solvent, and use citric acid and ethylene glycol as chelating agent and dispersant respectively in the preparation;

[0074] (2) Wet gel process: The mixed solution in step (1) is placed in a 95℃ constant temperature magnetic stirrer and stirred for 1 hour. The mixed solution changes from a clear blue state to a foaming wet gel with yellow smoke.

[0075] (3) Dry gel process: The wet gel obtained in step (2) is placed in a constant temperature oven at 140℃ for rapid foaming. After complete foaming, it is dried for 8 hours to finally obtain a loose dry gel without precipitation.

[0076] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar for about 0.5 hours. Then, it is calcined once in an air atmosphere for 8 hours at a calcination temperature of 400℃.

[0077] (5) Powder pressing process: After grinding the powder from step (4) again for 0.5 hours, press it into a block shape using an automatic tablet press. The mold size is 20 mm, the automatic tablet press is set to 5 MPa, and the pressing time is about 20 minutes.

[0078] (6) Secondary calcination process: The block material obtained in step (5) is calcined a second time in air atmosphere at a calcination temperature of 1200℃.

[0079] The Nd-doped uncooled infrared detector and Pr magnetic sensitizer obtained in Example 5 of this embodiment 1.6 Nd 0.4 NiO4 nickelate ceramics, as analyzed by SEM spectroscopy Figure 11 It can be seen that there is a precipitated phase Pr6O. 11 The addition of Nd increases the average grain size, leading to lattice distortion. Specifically, the room temperature resistivity reaches a minimum of 0.06 Ω·cm, and the TCR is -3.25%·K. -1 .

[0080] Example 6

[0081] The method for preparing an Nd-doped uncooled infrared detector and a magnetically sensitive nickelate ceramic as described in this embodiment includes the following steps.

[0082] (1) Solution preparation: Pr was prepared by sol-gel method. 2-x Nd x NiO4 ( x =0.4) Ceramic target material, weigh all raw materials of praseodymium nitrate, neodymium nitrate, nickel nitrate and citric acid according to the stoichiometric ratio, the weighing error of raw materials is controlled within ±0.0005g, aqueous solution is used as carrier of mixed raw materials, citric acid is used as chelating agent, and appropriate amount of ethylene glycol is used as dispersant.

[0083] (2) Wet gel process: Place the mixed solution of step (1) in a 95℃ constant temperature magnetic stirrer and stir for 1 hour. During the process of the mixed solution changing from a blue transparent state to a foaming and yellow smoke wet gel, the stirring speed is slowed down until it becomes a foaming wet gel state.

[0084] (3) Dry gel process: The wet gel obtained in step (2) is placed in a constant temperature oven for continued foaming. The drying temperature is 140℃ and the time is 12h. After the foaming is complete, it is fully dried to obtain a dry gel without precipitation.

[0085] (4) Calcination process: The dry gel from step (3) is ground into a fine and uniform precursor powder in an agate mortar for about 0.5 hours. Then, it is calcined once in an air atmosphere for 8 hours at a calcination temperature of 800℃.

[0086] (5) Powder pressing process: After grinding the powder from step (4) for 0.5 hours, press it into a block shape under an automatic tablet press. The mold size is 20 mm, the automatic tablet press is set to 6 MPa, and the time is 20 minutes.

[0087] (6) Secondary calcination process: The block material obtained in step (5) is calcined in air atmosphere for 12 hours at a calcination temperature of 1500℃.

[0088] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity, characterized in that, Specifically, the following steps are included: (1) Solution preparation: Weigh praseodymium nitrate, neodymium nitrate, nickel nitrate, and citric acid according to the required stoichiometric ratio and dissolve them in an aqueous solution. Add an appropriate amount of ethylene glycol as a dispersant to obtain a uniformly mixed solution; the chemical formula of the nickelate ceramic is Pr 2- x Nd x NiO4, where x = 0.4; (2) Wet gelation process: The homogeneous solution obtained in step (1) is placed on a 95℃ constant temperature magnetic stirrer and stirred and heated for 1 hour. (3) Dry gel process: The wet gel obtained in step (2) is subjected to a short-term rapid foaming reaction in a constant temperature oven at 140℃, and then dried in normal pressure and air atmosphere for 8-12 hours to obtain dry gel; (4) Calcination process: The dry gel formed in step (3) is ground into fine and uniform powder, and calcined at 400-800℃ in air atmosphere to obtain precursor powder; (5) Powder pressing process: The powder formed in step (4) is ground again and then pressed into blocks by an automatic tablet press with a pressing pressure of 5-6 MPa. (6) Secondary calcination process: The block material obtained by pressing in step (5) is calcined again at 1200-1500℃ in air atmosphere to obtain the nickelate ceramic.

2. The method for preparing an Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity as described in claim 1, characterized in that: In step (1), the weighing error of all raw materials is controlled within ±0.0005g.

3. The method for preparing an Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity as described in claim 1, characterized in that: In step (2), the stirring speed is slowed down as the mixed solution changes from a clear blue state to a foamy, yellow-smoking wet gel, until it becomes a foamy wet gel.

4. The method for preparing an Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity as described in claim 1, characterized in that: The grinding time in step (4) is 0.5 hours.

5. The method for preparing an Nd-doped uncooled infrared detector and a nickelate ceramic for magnetic sensitivity as described in claim 1, characterized in that: In step (5), the powder grinding time is 0.5h, the mold size is 20mm, and the pressing time is 20min.

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