Infrared sensor chip, preparation method thereof and infrared sensor

Abstract

The invention provides an infrared sensor chip, a preparation method thereof and an infrared sensor. The infrared sensor chip provided by the invention comprises the Mn-doped and modified KNN-based ceramic sensitive element, and has the advantages of small grain size and dielectric constant lt; according to the invention, the Curie temperature is higher than 428 DEG C, the optimal room temperature pyroelectric coefficient reaches 3.19 * 10 <-4 > C / m < 2 > / K, the response current of the infrared sensor reaches 0.307 nA, and the response of the infrared sensor to infrared radiation is improved; a small amount of Mn element enters a crystal lattice for substitution, crystal grain growth is promoted, polarization overturning is increased, pyroelectric performance is enhanced, the Curie temperature is high, dielectric loss is low, the temperature stability of polarization maintaining of KNN ceramic is widened by forming a Mn-related defect structure, response of an infrared sensor to infrared radiation change is improved, and the infrared sensor can be applied to infrared sensing. And the current signal is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared radiation sensors, and in particular to an infrared sensor chip and a preparation method thereof, and an infrared sensor. Background Art

[0002] In recent years, global resource consumption has continued to increase, traditional fossil fuels have become increasingly scarce, and environmental pollution has become more serious. People's demand for renewable clean energy has become more urgent. Therefore, new energy collection technologies have also become the focus of researchers, such as thermoelectric technology, photovoltaic solar cell technology, piezoelectric energy conversion technology, pyroelectric energy collection technology, etc. In terms of low-grade (25~205℃) waste heat, infrared radiation sensors using pyroelectric effect can effectively convert the heat changes of infrared radiation into electrical signals, which has good application prospects.

[0003] The key to pyroelectric infrared sensors lies in the performance of the sensitive element chip, which has the advantages of high sensitivity, wide temperature stability, low cost, small size, and no need for a refrigeration system or an external electric field.

[0004] Pyroelectric ceramics are an important class of key sensitive chip materials for infrared sensors. Currently, commercially available pyroelectric ceramics are mainly based on Pb-containing perovskite ceramics. In recent years, with the continuous development of lead-free electronic components, the development of new lead-free pyroelectric ceramics is imperative. 0.5 Na 0.5 NbO 3 (KNN) Ferroelectric ceramic systems have attracted extensive attention due to their high piezoelectric properties and high Curie temperature (~420°C), but the development of their pyroelectric properties is still immature. 0.5 Na 0.5 NbO 3 -0.03 (Bi 0.5 K 0.5 )TiO 3 The room temperature pyroelectric coefficient of ceramics is 1.01×10 - 4 C / m 2 / K, the Curie temperature is 350℃. At present, the room temperature pyroelectric performance of KNN-based ceramics is still insufficient, and its pyroelectric coefficient needs to be further improved to meet the application in infrared sensors. Therefore, the performance of sensitive element chips needs to be improved.

[0005] Based on the defects of the current KNN-based ceramic chips, it is necessary to improve them. Summary of the invention

[0006] The present invention aims at the problem that the infrared sensor adopts KNN-based ceramic sensitive element chip and has low room temperature pyroelectric performance, and provides an infrared sensor chip and its preparation method, and an infrared sensor. The infrared sensor chip of the present invention uses a method of metal manganese doping, and a small amount of Mn element enters the lattice to replace, promote grain growth, increase polarization reversal, enhance pyroelectric performance, and has a higher Curie temperature and lower dielectric loss. By forming a Mn-related defect structure, the temperature stability of KNN ceramics to maintain polarization is expanded. In this way, the response and sensitivity of the infrared sensor to infrared radiation are improved, and the current response is enhanced by more than 40%.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an infrared sensor chip, comprising: a ceramic sensitive element and metal electrodes located on the upper and lower surfaces of the ceramic sensitive element;

[0009] Wherein, the chemical formula of the ceramic sensitive element is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 -x%MnO 2 , where x% represents MnO 2 The molar number is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 The percentage of moles, 0 <x≤2。

[0010] Preferably, the material of the metal electrode includes at least one of Ag, Cu, Au and Ni;

[0011] And / or, the thickness of the ceramic sensitive element is 0.1-0.2 mm;

[0012] And / or, the thickness of the metal electrode is 5-15 μm.

[0013] In a second aspect, the present invention further provides a method for preparing the infrared sensor chip, comprising the following steps:

[0014] According to the stoichiometric ratio of each element in the chemical formula of the ceramic sensitive element, K source, Na source, Bi source, Nb source, Al source, Li source, and Mn source are weighed respectively, and mixed to obtain a mixed raw material;

[0015] After ball milling, the mixed raw materials are pre-sintered for the first time at 800-900°C;

[0016] After the powder is pre-fired for the first time, it is ball-milled and then pre-fired for the second time;

[0017] The powder after the second pre-sintering is ball-milled to obtain ceramic powder;

[0018] Adding a binder to the ceramic powder, granulating, pressing, and debinding to obtain a ceramic body;

[0019] The ceramic green body is sintered at 1100-1150°C to obtain a ceramic sintered body, which is a ceramic sensitive element;

[0020] Metal conductive paste is printed on the upper and lower surfaces of the ceramic sintered body, and sintered at 600-800°C to obtain an infrared sensor chip.

[0021] Preferably, the K source is K 2 CO 3 , the Na source is Na 2 CO 3 , the Bi source is Bi 2 O 3 , the Nb source is Nb 2 O 5 , the Al source is Al 2 O 3 , the Li source is Li 2 CO 3 , the Mn source

[0022] Including MnO 2 、MnO、MnCO 3 At least one of;

[0023] Among them, the K 2 CO 3 、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O 3 、Al 2 O 3 、MnO 2The molar ratio is (0.48×0.95×0.995~0.48×0.95×0.995×1.02):(0.52×0.95×0.995~0.52×0.95×0.995×1.02):(0.05×0.995~0.05×0.995×1.02):0.995:(0.005~0.005×1.02):0.005:(x / 50), 0 <x≤2。

[0024] Preferably, after ball milling the mixed raw material, the first pre-sintering is performed at 800-900° C., wherein the first pre-sintering time is 3-6 h;

[0025] And / or, the second pre-firing temperature is 800-900° C. and the time is 3-6 hours;

[0026] And / or, the binder is a PVA aqueous solution with a mass concentration of 3-7%;

[0027] And / or, in the step of adding a binder to the ceramic powder, the amount of the binder added does not exceed 5% of the mass of the ceramic powder.

[0028] Preferably, a binder is added to the ceramic powder, granulated, pressed into a cylinder with a diameter of 10-15 mm, and kept at 600-650° C. for 2-3 hours for debinding to obtain a ceramic green body.

[0029] Preferably, the ceramic green body is heated to 1100-1150° C. at 5-6° C. / min and kept at that temperature for 2-3 hours for sintering to obtain a ceramic sintered body;

[0030] Then, the ceramic sintered body is ground with sandpaper of 600-2000 meshes, and then polished to a thickness of 100-200 μm to obtain a ceramic sensitive element.

[0031] Preferably, the metal conductive paste is printed on the upper and lower surfaces of the ceramic sintered body, and sintered at 600-800° C. for 10-15 min to obtain the infrared sensor chip.

[0032] In a third aspect, the present invention further provides an infrared sensor, comprising the infrared sensor chip described above or the infrared sensor chip prepared by the preparation method described above.

[0033] Preferably, it also includes: a housing;

[0034] A PCB substrate is provided in the housing, the infrared sensor chip is located on the surface of the PCB substrate, and the surface of the infrared sensor chip provided with the metal electrode is perpendicular to the surface of the PCB substrate;

[0035] A first window is provided on the upper surface of the housing corresponding to the infrared sensor chip, and a refractor is provided in the first window;

[0036] Second windows are provided on both sides of the shell corresponding to the infrared sensor chip;

[0037] An infrared radiation reflector is also provided in the housing;

[0038] Among them, the infrared light enters the infrared radiation reflector after being refracted by the refractor, and is reflected onto the metal electrode of the infrared sensor chip;

[0039] The infrared light passes through the second window and irradiates the metal electrode of the infrared sensor chip.

[0040] The infrared sensor chip and its preparation method and the infrared sensor of the present invention have the following beneficial effects compared with the prior art:

[0041] 1. The infrared sensor chip of the present invention adopts a simple parallel plate capacitor structure, including upper and lower parallel symmetrical metal electrodes, between which is a Mn-doped modified KNN-based ceramic sensitive element, the chemical composition of which is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 -x%MnO 2 The high-temperature pyroelectric ceramic sensitive element prepared by the present invention has a small grain size (about 2 μm), a dielectric constant <1000, a coexistence of orthorhombic phase and tetragonal phase at room temperature, a Curie temperature greater than 428°C, and an optimal room temperature pyroelectric coefficient of 3.19×10 -4 C / m 2 / K, which is more than 40% higher than that of the undoped component. At this time, the response current of the infrared sensor measured by the direct method reaches 0.307nA, which improves the response of the infrared sensor to infrared radiation; the present invention improves the air sintering process of KNN ceramics by introducing an appropriate amount of Mn elements, does not require special equipment, has low cost, and is suitable for large-scale production; a small amount of Mn elements enter the lattice to replace, promote grain growth, increase polarization reversal, enhance pyroelectric properties, have a higher Curie temperature and lower dielectric loss, and expand the temperature stability of KNN ceramics to maintain polarization by forming Mn-related defect structures, thereby improving the response of the infrared sensor to changes in infrared radiation and enhancing the current signal;

[0042] 2. The infrared sensor of the present invention mounts the infrared sensor chip upright and vertically mounts it on a substrate such as a PCB. Through the optical path design, a window parallel to the chip is added to fully utilize the absorption of infrared radiation by the front and back surfaces of the chip, thereby improving the output electrical signal of the infrared sensor and converting more infrared radiation energy into electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 It is a structural schematic diagram of the infrared sensor chip of the present invention;

[0045] Figure 2 It is a structural schematic diagram of the infrared sensor of the present invention;

[0046] Figure 3 XRD diagrams of the ceramic sensitive elements prepared in Examples 1 to 4 and Comparative Example 1;

[0047] Figure 4 is a scanning electron microscope image of the ceramic sensitive element prepared in Example 1;

[0048] Figure 5 is a grain size distribution diagram of the ceramic sensitive element prepared in Example 1;

[0049] Figure 6 The dielectric constant of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature;

[0050] Figure 7 The dielectric loss of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature;

[0051] Figure 8 The pyroelectric coefficient of the infrared sensor chip prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature;

[0052] Fig. 9 The pyroelectric current density of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature. DETAILED DESCRIPTION

[0053] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any quoted numbers (fractions or integers) within the indicated range.

[0056] The present application embodiment provides an infrared sensor chip, such as Figure 1 As shown, it includes: a ceramic sensitive element 1 and metal electrodes 2 located on the upper and lower surfaces of the ceramic sensitive element 1;

[0057] Among them, the chemical formula of the ceramic sensitive element is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 -x%MnO 2 , where x% represents MnO 2 The molar number is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 The percentage of moles, 0 <x≤2。

[0058] In some embodiments, the material of the metal electrode includes but is not limited to at least one of Ag, Cu, Au, Ni, and Ti.

[0059] In some embodiments, the thickness of the ceramic sensitive element is 0.1 - 0.2 mm.

[0060] In some embodiments, the thickness of the metal electrode is 5 - 15 μm.

[0061] The infrared sensor chip of the present invention adopts a simple parallel - plate capacitor structure, including upper and lower parallel and symmetric metal electrodes, and a Mn - doped modified KNN - based ceramic sensitive element is between the metal electrodes; by adding MnO in the K 0.48 Na 0.52 NbO 3 -BiAlO 3 (KNN - BAO) ceramic chip, its sintering characteristics are improved, and the pyroelectric performance of the pyroelectric infrared sensor at room temperature is enhanced. The chemical composition of the ceramic sensitive element is 0.995[(K 2 Na 0.48 ) 0.52 Li 0.95 NbO 0.05 -0.005BiAlO 3 -x%MnO 3 (KNLN - BAO - x%MnO 2 ), 0 < x ≤ 2, specifically x is 0.1, 0.5, 1, 2... etc. When x = 0.1, the Curie temperature of its lead - free pyroelectric ceramic material is greater than ~428°C, the average grain size is about 2 microns, the ceramic is sintered densely, its room - temperature phase structure co - exists with orthorhombic phase and tetragonal phase, and the room - temperature pyroelectric coefficient is optimal (3.19×10 2 C / m -4 / K), which is more than 40% higher than that of the undoped component. At this time, the response current of the infrared sensor measured by the direct method reaches 0.307 nA. 2 / K), which is more than 40% higher than that of the undoped component. At this time, the response current of the infrared sensor measured by the direct method reaches 0.307 nA.

[0062] Based on the same inventive concept, the present invention also provides a preparation method of the above - mentioned infrared sensor chip, including the following steps:

[0063] S1. Weigh the K source, Na source, Bi source, Nb source, Al source, Li source, and Mn source respectively according to the stoichiometric ratio of each element in the chemical formula of the ceramic sensitive element, and mix them to obtain a mixed raw material;

[0064] S2. After ball - milling the mixed raw material, perform the first pre - sintering at 800 - 900°C;

[0065] S3, ball-milling the powder after the first pre-calcination, and then pre-calcining for the second time;

[0066] S4, ball-milling the powder after the second pre-sintering to obtain ceramic powder;

[0067] S5, adding a binder to the ceramic powder, granulating, pressing, and debinding to obtain a ceramic body;

[0068] S6, sintering the ceramic body at 1100-1150° C. to obtain a ceramic sintered body, which is a ceramic sensitive element;

[0069] S7. Printing metal conductive paste on the upper and lower surfaces of the ceramic sintered body, sintering at 600-800° C. to obtain an infrared sensor chip.

[0070] In some embodiments, the K source is K 2 CO 3 , the source of Na is Na 2 CO 3 , Bi source is Bi 2 O 3 , Nb source is Nb 2 O 5 , Al source is Al 2 O 3 , Li source is Li 2 CO 3 The Mn source includes but is not limited to MnO 2 , MnO, MnCO 3 Such manganese oxides or carbonates.

[0071] In some embodiments, K 2 CO 3 、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O 3 、Al 2 O 3 、MnO 2 The molar ratio is (0.48×0.95×0.995~0.48×0.95×0.995×1.02):(0.52×0.95×0.995~0.52×0.95×0.995×1.02):(0.05×0.995~0.05×0.995×1.02):0.995:(0.005~0.005×1.02):0.005:(x / 50), 0 <x≤2。

[0072] In the above embodiment, since K2 CO 3 、Na 2 CO 3 、Bi 2 O 3 , Li 2 CO 3 It is a volatile component. In order to compensate for its partial volatilization during the sintering process, the volatile component is excessive based on the molar ratio corresponding to its chemical formula, and the excess amount is less than or equal to 2% mol.

[0073] In some embodiments, after ball milling the mixed raw material, the first pre-sintering is performed at 800-900° C., wherein the first pre-sintering time is 3-6 h;

[0074] In some embodiments, the second pre-firing temperature is 800-900° C. and the time is 3-6 hours.

[0075] In some embodiments, a binder is added to the ceramic powder, granulated, pressed into a cylinder with a diameter of 10-15 mm, and kept at 600-650° C. for 2-3 hours to debind, thereby obtaining a ceramic green body.

[0076] In some embodiments, the binder is a PVA (polyvinyl alcohol) aqueous solution with a mass concentration of 3-7%, and the purpose of debinding is to remove the colloid (ie, PVA); in the step of adding the binder to the ceramic powder, the amount of the binder added does not exceed 5% of the mass of the ceramic powder.

[0077] In some embodiments, the ceramic body is heated to 1100-1150° C. at a rate of 5-6° C. / min and kept at that temperature for 2-3 hours for sintering to obtain a ceramic sintered body;

[0078] Then, the ceramic sintered body is ground with sandpaper of 600-2000 meshes, and then polished to a thickness of 100-200 μm to obtain a ceramic sensitive element.

[0079] In some embodiments, a metal conductive paste is printed on the upper and lower surfaces of a ceramic sintered body, and the body is sintered at 600-800° C. for 10-15 min to obtain an infrared sensor chip.

[0080] The infrared sensor chip prepared by the present invention has a small grain size (about 2 μm), a dielectric constant <1000, a coexistence of orthorhombic phase and tetragonal phase at room temperature, a Curie temperature greater than 428°C, and an optimal room temperature pyroelectric coefficient of 3.19×10 -4 C / m 2 / K, which is more than 40% higher than that of the undoped component. At this time, the response current of the infrared sensor measured by the direct method reaches 0.307nA, which improves the response of the infrared sensor to infrared radiation; the present invention improves the air sintering process of KNN ceramics by introducing an appropriate amount of Mn element, does not require special equipment, has low cost, and is suitable for large-scale production; a small amount of Mn element enters the lattice to replace, promotes grain growth, increases polarization reversal, enhances pyroelectric properties, has a higher Curie temperature and lower dielectric loss, and expands the temperature stability of KNN ceramics to maintain polarization by forming Mn-related defect structures, thereby improving the response of the infrared sensor to changes in infrared radiation and enhancing the current signal.

[0081] Based on the same inventive concept, the present invention further provides an infrared sensor, comprising the above-mentioned infrared sensor chip or the infrared sensor chip prepared by the above-mentioned preparation method.

[0082] In some embodiments, Figure 2 As shown, it also includes: a housing 4;

[0083] A PCB substrate 3 is provided in the housing, and the infrared sensor chip is located on the surface of the PCB substrate 3. The surface of the infrared sensor chip provided with the metal electrode 2 is perpendicular to the surface of the PCB substrate 3.

[0084] A first window 5 is provided on the upper surface of the housing 4 at a position corresponding to the infrared sensor chip, and a refractor is provided in the first window 5;

[0085] Second windows 6 are provided on both sides of the housing 4 corresponding to the infrared sensor chip;

[0086] An infrared radiation reflector 7 is also provided in the housing 4 .

[0087] Specifically, Figure 2 As shown, the infrared light a is incident on the refraction mirror in the first window 5 and then refracted and enters the infrared radiation reflector 7, and is reflected onto the metal electrode 2 of the infrared sensor chip; the infrared light a can pass through the second window 6 without being refracted and directly irradiate the metal electrode 2 of the infrared sensor chip.

[0088] The infrared sensor of the present invention mounts the infrared sensor chip upright and vertically mounts it on a substrate such as a PCB. Through the optical path design, a second window is added parallel to the chip direction, and the absorption of infrared radiation by the front and back surfaces of the chip is fully utilized, thereby improving the output electrical signal of the infrared sensor and converting more infrared radiation energy into electrical energy.

[0089] The infrared sensor chip and its preparation method and infrared sensor of the present application are further described below with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0090] Example 1

[0091] The embodiment of the present application provides an infrared sensor chip, comprising: a ceramic sensitive element and metal electrodes located on the upper and lower surfaces of the ceramic sensitive element;

[0092] Among them, the chemical formula of the ceramic sensitive element is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 -x%MnO 2 , where x% represents MnO 2 The molar number is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 The percentage of moles, x=0.1;

[0093] The metal electrode is a silver electrode;

[0094] The thickness of the ceramic sensitive element is 0.15 mm;

[0095] The thickness of the metal electrode is 10 μm.

[0096] The method for preparing the infrared sensor chip comprises the following steps:

[0097] S1, K 2 CO 3 、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O 3 、Al 2 O 3 、MnO 2 Mix to obtain a mixed raw material; wherein K 2 CO 3、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O 3 、Al 2 O 3 、MnO 2 The molar ratio is (0.48×0.95×0.995×1.02):(0.52×0.95×0.995×1.02):(0.05×0.995×1.02):0.995:( 0.005×1.02):0.005:(x / 50), x=0.1;

[0098] S2, after ball milling the mixed raw materials, pre-sintering for the first time at 850°C for 4 hours;

[0099] S3, after ball milling the powder after the first pre-sintering, pre-sintering for the second time at 850°C for 4 hours;

[0100] S4, ball-milling the powder after the second pre-sintering to obtain ceramic powder;

[0101] S5, adding a binder to the ceramic powder, granulating, pressing into a cylinder with a diameter of 12 mm, and keeping at 630°C for 2 hours to remove binder to obtain a ceramic body; the binder is a PVA (polyvinyl alcohol) aqueous solution with a mass concentration of 5%; the amount of the binder added is 4% of the mass of the ceramic powder;

[0102] S6, heating the ceramic body to 1120° C. at a rate of 5° C. / min and maintaining the temperature for 2 h to sinter the ceramic body to obtain a ceramic sintered body;

[0103] Then, the ceramic sintered body is ground with 1000-grit sandpaper and then polished to a thickness of 150 μm (i.e., 0.15 mm) to obtain a ceramic sensitive element;

[0104] S7. Printing metallic silver conductive paste on the upper and lower surfaces of the ceramic sensitive element, keeping the temperature at 700° C. for 10 minutes, and obtaining an infrared sensor chip.

[0105] Example 2

[0106] The infrared sensor chip and the preparation method thereof provided in the embodiment of the present application are the same as those in Embodiment 1, except that x=0.5, and the rest are the same as those in Embodiment 1.

[0107] Example 3

[0108] The infrared sensor chip and the preparation method thereof provided in the embodiment of the present application are the same as those in Embodiment 1, except that x=1, and the rest are the same as those in Embodiment 1.

[0109] Example 4

[0110] The infrared sensor chip and the preparation method thereof provided in the embodiment of the present application are the same as those in Embodiment 1, except that x=2, and the rest are the same as those in Embodiment 1.

[0111] Comparative Example 1

[0112] The infrared sensor chip provided in this comparative example is the same as that in Example 1, except that x=0, and the rest is the same as that in Example 1;

[0113] Specifically, the infrared sensor chip includes: a ceramic sensitive element and metal electrodes located on the upper and lower surfaces of the ceramic sensitive element;

[0114] Among them, the chemical formula of the ceramic sensitive element is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO 3 ]-0.005BiAlO 3 ;

[0115] The metal electrode is a silver electrode;

[0116] The thickness of the ceramic sensitive element is 0.15 mm;

[0117] The thickness of the metal electrode is 10 μm.

[0118] The method for preparing the infrared sensor chip comprises the following steps:

[0119] S1, K 2 CO 3 、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O 3 、Al 2 O 3 Mix to obtain a mixed raw material; wherein K 2 CO 3 、Na 2 CO 3 , Li 2 CO 3 , Nb 2 O 5 、Bi 2 O3 , Al 2 O 3 The molar ratio of is (0.48×0.95×0.995×1.02):(0.52×0.95×0.995×1.02):(0.05×0.995×1.02):0.995:(0.005×1.02):0.005;

[0120] S2. After ball-milling the mixed raw materials, perform the first pre-sintering at 850 °C for 4 h;

[0121] S3. After ball-milling the powder after the first pre-sintering, perform the second pre-sintering at 850 °C for 4 h;

[0122] S4. After ball-milling the powder after the second pre-sintering, obtain the ceramic powder;

[0123] S5. Add a binder to the ceramic powder, granulate, press it into a cylinder with a diameter of 12 mm, and perform debinding at 630 °C for 2 h to obtain a ceramic green body; the binder is an aqueous solution of PVA (polyvinyl alcohol) with a mass concentration of 5%; the addition amount of the binder is 4% of the mass of the ceramic powder;

[0124] S6. Heat the ceramic green body from room temperature to 1120 °C at a rate of 5 °C / min and hold for 2 h for sintering to obtain a ceramic sintered body;

[0125] Then polish the ceramic sintered body with 1000-mesh sandpaper and then polish it to a thickness of 150 μm to obtain the ceramic sensitive element;

[0126] S7. Print metal silver conductive paste on the upper and lower surfaces of the ceramic sensitive element, hold at 700 °C for 10 min to form silver electrodes, and obtain an infrared sensor chip; among them, the diameter of the silver electrode is 6 mm and the area is 28.26 mm 2 .

[0127] Performance Test

[0128] Figure 3 XRD patterns of the ceramic sensitive elements prepared in Examples 1 to 4 and Comparative Example 1; among them, x = 0.1 corresponds to Example 1, x = 0.5 corresponds to Example 2, x = 1 corresponds to Example 3, x = 2 corresponds to Example 4, and x = 0 corresponds to Comparative Example 1.

[0129] It can be seen from Figure 3 that for the ceramic sensitive element prepared by the present invention, in the range of KNLN - BAO - x%MnO 2 , where 0 < x ≤ 2, no second phase is found in its XRD results, and it is mainly composed of orthorhombic phase and tetragonal phase.

[0130] Figure 4 This is a scanning electron microscope image of the ceramic sensitive element prepared in Example 1.

[0131] from Figure 4 It can be seen that the ceramic sensitive element prepared in Example 1 has an elliptical grain shape, is densely arranged, and has good growth.

[0132] Figure 5 This is a grain size distribution diagram of the ceramic sensitive element prepared in Example 1.

[0133] from Figure 5 It can be seen from the figure that the grain size distribution of the ceramic sensitive element is concentrated around 2 μm.

[0134] The dielectric constant and dielectric loss of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 were tested using an LCR meter at a test frequency of 1 kHz and a temperature of 25 to 450°C. The pyroelectric coefficient and pyroelectric current of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 were tested; the pyroelectric coefficient and pyroelectric current were tested using the direct method (Byer-Roundy Method). The infrared sensor chip was polarized in 40°C silicone oil under a 5 kV / mm DC electric field for 15 min and short-circuited at room temperature for 12 to 24 h. The pyroelectric current performance of the chip was then tested using a picoammeter at a heating rate of 2°C / min and a test temperature range of 0 to 200°C. The pyroelectric current i was recorded and then calculated using the formula Calculate the pyroelectric coefficient, where p is the pyroelectric coefficient and A is the electrode area (the silver electrode area in this embodiment and comparative example 1 is 28.26 mm 2 ), T is the ambient temperature, t is the time.

[0135] Specifically, Figure 6 The dielectric constant (Dielectric constant) of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature; Figure 7 The figure is a graph showing the dielectric loss of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 as a function of temperature; wherein x=0.1 corresponds to Example 1, x=0.5 corresponds to Example 2, x=1 corresponds to Example 3, x=2 corresponds to Example 4, and x=0 corresponds to Comparative Example 1.

[0136] from Figure 6 It can be seen that below 350°C, the dielectric constant changes slowly with increasing temperature from room temperature, and changes dramatically around 400°C. The dielectric constant changes dramatically due to the phase transition from the orthorhombic phase to the cubic phase. The Curie temperature of the infrared sensor chip prepared by the present invention is greater than 428°C.

[0137] from Figure 7 It can be seen that the introduction of Mn elements can suppress the dielectric loss of the sensitive element chip at room temperature. Below 200°C, the dielectric loss of the sensitive element changes steadily; above 250°C, the dielectric loss of the doped sensitive element increases dramatically due to the increase in leakage conductance at high temperature.

[0138] Figure 8 The pyroelectric coefficient of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature.

[0139] Fig. 9 The pyroelectric current density of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1 varies with temperature.

[0140] in, Figures 8 and 9 0.1% corresponds to Example 1, 0.5% corresponds to Example 2, 1% corresponds to Example 3, 2% corresponds to Example 4, and 0% corresponds to Comparative 1.

[0141] from Figure 8 It can be seen that in Example 1, when x=0.1, its room temperature pyroelectric coefficient is increased by more than 40% compared with the undoped component.

[0142] Fig. 9 The current responses of the infrared sensor chips corresponding to x=0, 1, 0.5, 1, 2 at different temperatures are shown. When x=0.1, the room temperature response current of the infrared sensor chip reaches -0.307nA (where "-" indicates that its direction is opposite to that of the reference current).

[0143] Table 1 below shows the performance of the infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1.

[0144] Table 1 - Performance of infrared sensor chips prepared in Examples 1 to 4 and Comparative Example 1

[0145]

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An infrared sensor chip, characterized in that: include: A ceramic sensitive element and metal electrodes located on the upper and lower surfaces of the ceramic sensitive element; Wherein, the chemical formula of the ceramic sensitive element is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO3]-0.005BiAlO3-x%MnO2, where x% represents the molar number of MnO2 is 0.995[(K 0.48 Na 0.52 ) 0.95 Li 0.05 NbO3]-0.005BiAlO3 molar percentage, 0 <x≤2。 2. The infrared sensor chip according to claim 1, characterized in that: The material of the metal electrode includes at least one of Ag, Cu, Au, and Ni; And / or, the thickness of the ceramic sensitive element is 0.1-0.2 mm; And / or, the thickness of the metal electrode is 5-15 μm.

3. A method for preparing an infrared sensor chip according to any one of claims 1 to 2, characterized in that: The following steps are involved: According to the stoichiometric ratio of each element in the chemical formula of the ceramic sensitive element, K source, Na source, Bi source, Nb source, Al source, Li source, and Mn source are weighed respectively, and mixed to obtain a mixed raw material; After ball milling, the mixed raw materials are pre-sintered for the first time at 800-900°C; After the powder is pre-fired for the first time, it is ball-milled and then pre-fired for the second time; The powder after the second pre-sintering is ball-milled to obtain ceramic powder; Adding a binder to the ceramic powder, granulating, pressing, and debinding to obtain a ceramic body; The ceramic green body is sintered at 1100-1150°C to obtain a ceramic sintered body, which is a ceramic sensitive element; Metal conductive paste is printed on the upper and lower surfaces of the ceramic sintered body, and sintered at 600-800°C to obtain an infrared sensor chip.

4. The method for preparing the infrared sensor chip according to claim 3, characterized in that: The K source is K2CO3, the Na source is Na2CO3, the Bi source is Bi2O3, the Nb source is Nb2O5, the Al source is Al2O3, the Li source is Li2CO3, and the Mn source includes at least one of MnO2, MnO, and MnCO3; Wherein, the molar ratio of K2CO3, Na2CO3, Li2CO3, Nb2O5, Bi2O3, Al2O3 and MnO2 is (0.48×0.95×0.995~0.48×0.95×0.995×1.02):(0.52×0.95×0.995~0.52×0.95×0.995×1.02):(0.05×0.995~0.05×0.995×1.02):0.995:(0.005~0.005×1.02):0.005:(x / 50), 0 <x≤2。 5. The method for preparing the infrared sensor chip according to claim 3, characterized in that: After ball milling the mixed raw materials, the first pre-sintering is performed at 800-900°C, wherein the first pre-sintering time is 3-6 h; And / or, the second pre-firing temperature is 800-900° C. and the time is 3-6 hours; And / or, the binder is a PVA aqueous solution with a mass concentration of 3-7%; And / or, in the step of adding a binder to the ceramic powder, the amount of the binder added does not exceed 5% of the mass of the ceramic powder.

6. The method for preparing the infrared sensor chip according to claim 3, characterized in that: A binder is added to the ceramic powder, granulated, pressed into a cylinder with a diameter of 10-15 mm, and kept at 600-650°C for 2-3 hours to debind, thereby obtaining a ceramic green body.

7. The method for preparing an infrared sensor chip according to claim 3, characterized in that: The ceramic body is heated to 1100-1150°C at a rate of 5-6°C / min and kept at that temperature for 2-3 hours for sintering to obtain a ceramic sintered body; Then, the ceramic sintered body is ground with sandpaper of 600-2000 meshes, and then polished to a thickness of 100-200 μm to obtain a ceramic sensitive element.

8. The method for preparing an infrared sensor chip according to claim 3, characterized in that: The metal conductive paste is printed on the upper and lower surfaces of the ceramic sintered body, and sintered at 600-800°C for 10-15 minutes to obtain an infrared sensor chip.

9. An infrared sensor, characterized in that: It comprises the infrared sensor chip as claimed in claim 1 or 2 or the infrared sensor chip prepared by the preparation method according to any one of claims 3 to 8.

10. The infrared sensor according to claim 9, characterized in that: Also includes: case; A PCB substrate is provided in the housing, the infrared sensor chip is located on the surface of the PCB substrate, and the surface of the infrared sensor chip provided with the metal electrode is perpendicular to the surface of the PCB substrate; A first window is provided on the upper surface of the housing corresponding to the infrared sensor chip, and a refractor is provided in the first window; Second windows are provided on both sides of the shell corresponding to the infrared sensor chip; An infrared radiation reflector is also provided in the housing; Among them, the infrared light enters the infrared radiation reflector after being refracted by the refractor, and is reflected onto the metal electrode of the infrared sensor chip; The infrared light passes through the second window and irradiates the metal electrode of the infrared sensor chip.

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