A wireless passive temperature sensor ceramic material and a method of manufacturing the same

Abstract

This invention relates to the field of dielectric ceramic materials, and discloses a ceramic material for a wireless passive temperature sensor and its preparation method. The chemical composition of the ceramic is (Pb) 1‑x A x )[(Yb 1‑y B y ) 0.5 Nb 0.5 O3, where A is one of Ca and Sr, B is one of In and Lu, 0≤x≤0.06, 0≤y≤0.01; the ceramic is a lead ytterbium niobate-based dielectric ceramic with a Curie temperature of 300 ℃. The wireless passive temperature sensor made of this ceramic has an operating temperature of 20~200 ℃, a nonlinearity error of 5~5.5%, and a sensitivity of 0.22~0.23% / ℃. It also has a wide operating temperature, high sensitivity, and high linearity. The dielectric constant of this ceramic remains stable in the frequency range of 20~200 ℃ and 1~100 kHz, and the dielectric loss is less than 0.04.

Description

Technical Field

[0001] This invention relates to the field of dielectric ceramic materials, and in particular to a ceramic material for a wireless passive temperature sensor and its preparation method. Background Technology

[0002] The permittivity (also known as dielectric constant) of dielectric materials changes with temperature, causing the capacitance of capacitors using dielectric materials as the dielectric to change with temperature, and consequently altering the resonant frequency of the resonant circuit using that capacitor. Therefore, dielectric materials are commonly used in temperature sensors that directly measure capacitance or in wireless passive temperature sensors that measure the resonant frequency of a resonant cavity.

[0003] Traditional wireless passive temperature sensors use linear dielectric materials, such as alumina, for their resonant cavity. However, alumina has a capacitance change rate of approximately 0.01% / ℃, which is low. The rate of capacitance change with temperature determines the sensitivity of the temperature sensor, leading to low sensitivity in temperature sensors made with traditional linear dielectrics. For example, CN118145996A discloses a low-dielectric microwave dielectric ceramic material for wireless passive temperature sensors and its preparation method. Most ferroelectric and antiferroelectric materials generally exhibit multiple structural phase transitions, thus possessing higher capacitance change rates (far exceeding 1% / ℃ near the phase transition temperature range), resulting in higher sensitivity. However, they exhibit nonlinearity or a narrow linear temperature range. Currently known dielectric materials for temperature sensors generally suffer from low sensitivity, low operating temperature, or narrow operating range, preventing their application in high-temperature, high-sensitivity, and high-linearity environments. Therefore, to address these issues, a dielectric material for temperature sensors that simultaneously possesses a wide operating temperature range, high sensitivity, and high linearity is needed. Summary of the Invention

[0004] This invention provides a ceramic material for a wireless passive temperature sensor and its preparation method. The ceramic is an antiferroelectric material with a perovskite structure and a Curie temperature of approximately 300 °C. It has a wide operating temperature range. The ceramic exhibits a nonlinearity error of 5.2% in the permittivity range of 20–200 °C and a sensitivity of 0.22% / °C, demonstrating high linearity and high sensitivity.

[0005] The specific technical solution of this invention is as follows: A wireless passive temperature sensor ceramic material with the chemical composition (Pb) 1-x A x )[(Yb 1-y B y ) 0.5 Nb 0.5 O3, where A is one of Ca and Sr, B is one of In and Lu, 0≤x≤0.06, 0≤y≤0.01.

[0006] This invention provides a ceramic material for a wireless passive temperature sensor. This ceramic is a perovskite-structured antiferroelectric material, and its low-temperature ion displacements differ from the parallel arrangement of ferroelectric materials, exhibiting an antiparallel arrangement. Its B-sites contain trivalent and pentavalent cations with significant differences in half-length and valence, enabling the formation of a highly stable antiparallel antiferroelectric structure. Only one structural phase transition, antiferroelectric = paraelectric, exists, and the phase transition temperature is high, reaching a Curie temperature of 300 °C. This ceramic maintains a stable dielectric constant (dielectric constant variation of 80–200) within the frequency range of 20–200 °C and 1–100 kHz, with a dielectric loss below 0.04.

[0007] A method for preparing the above-mentioned ceramic material for a wireless passive temperature sensor includes the following steps: (1) Yb2O3 and Nb2O5 were ball-milled to form a slurry, and the slurry was dried and calcined to form a YbNbO4 precursor; (2) YbNbO4 precursor, Pb3O4 and other oxide raw materials are ball-milled to prepare precursor slurry, and the precursor slurry is dried, sieved and pre-calcined to prepare pre-calcined material; (3) The pre-fired material is ball-milled to make a pre-fired slurry, and the pre-fired slurry is dried to make a powder. (4) Press the powder into a blank and sinter the blank to make a wireless passive temperature sensor ceramic material.

[0008] Preferably, the calcination temperature is 1200~1300 ℃.

[0009] Preferably, the calcination time is 4-5 hours.

[0010] Preferably, the pre-firing temperature is 830~850 ℃.

[0011] Preferably, the preheating time is 3-4 hours.

[0012] Preferably, the ball milling process uses a zirconia ball mill and anhydrous ethanol.

[0013] Preferably, the ratio of powder, milling ball, and anhydrous ethanol during ball milling is 1:2:4.

[0014] Preferably, the other oxide raw materials are one or more of strontium carbonate, lutetium oxide, calcium oxide, and indium oxide.

[0015] Preferably, the sintering temperature is 900~1100 ℃.

[0016] Preferably, the sintering time is 2 to 4 hours.

[0017] Preferably, cold isostatic pressing is used, with a pressure of 200~220 MPa and a time of 5~8 min.

[0018] This invention also provides a method for preparing the aforementioned wireless passive temperature sensor ceramic material. This method uses Yb₂O₃ and Nb₂O₅ to prepare a YbNbO₄ precursor. The wireless passive temperature sensor ceramic material is then prepared using the YbNbO₄ precursor along with other oxide raw materials and Pb₃O₄. This method avoids the problem of pyrochlore impurities easily generated during one-step synthesis. Furthermore, this invention also found that PbO volatilizes at high temperatures; therefore, Pb₃O₄ raw material needs to be prepared in excess, requiring an increase of 2 wt% Pb₃O₄ above the conventional ratio. The excess Pb₃O₄ ensures that the PbO content remains consistent with the set ratio after high-temperature preparation.

[0019] The application of the aforementioned wireless passive temperature sensor ceramic material in the manufacture of a wireless passive temperature sensor includes the following steps: forming the wireless passive temperature sensor ceramic material into a ceramic disc, and setting electrode layers on both sides of the ceramic disc to form a temperature sensor element.

[0020] Preferably, the electrode layer is made of either silver or platinum.

[0021] Compared with the prior art, this application has the following technical effects: (1) The chemical formula of the dielectric ceramic provided by this invention is (Pb 1-x A x )[(Yb 1-y B y ) 0.5 Nb 0.5 O3, this ceramic is a ceramic material for wireless passive temperature sensors, and the Curie temperature of this ceramic is 300 ℃; (2) The temperature sensor made of ceramic material provided by the present invention has a working temperature of 20~200 ℃, a nonlinear error of 5~5.5% at 20~200 ℃, and a sensitivity of 0.22~0.23% / ℃. It also has a wide working temperature, high sensitivity and high linearity. The dielectric constant of the ceramic remains stable in the frequency range of 20~200 ℃ and 1~100KHz and the dielectric loss is less than 0.04. Attached Figure Description

[0022] Figure 1 This is a physical image of the ceramic material used in a wireless passive temperature sensor.

[0023] Figure 2 The image shows the X-ray diffraction pattern of the ceramic material of the wireless passive temperature sensor in Example 1.

[0024] Figure 3The figures show the curves of relative permittivity and dielectric loss of the ceramic material of the wireless passive temperature sensor in Example 1 as a function of temperature at frequencies of 1 kHz, 10 kHz and 100 kHz, with a temperature range of 20~200 ℃. In the figure, (a) is the curve of relative permittivity and dielectric loss as a function of temperature, and (b) is the fitted straight line of relative permittivity in the range of 20~200 ℃. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments.

[0026] To better understand the content of this invention, further explanation is provided below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0027] Example 1: A method for preparing a ceramic material for a wireless passive temperature sensor includes the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.96 Sr 0.04 )[(Yb 0.995 Lu 0.005 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. The raw materials are Yb2O3, Nb2O5, SrCO3, Lu2O3 and Pb3O4. (2) Yb2O3 and Nb2O5 were mixed into powder. The powder, zirconia ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to make a slurry. The ball milling speed was 500 rpm and the time was 36 h. The slurry was placed in a 120 ℃ oven to dry. After drying, it was calcined at 1200 ℃ for 4 h and then ground to make YbNbO4 precursor powder. (3) Mix YbNbO4 precursor powder, SrCO3, Lu2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powdered zirconia ball mill and anhydrous ethanol at a mass ratio of 1:2:4 and then ball mill to prepare precursor slurry. Place the precursor slurry in an oven at 120 ℃ to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 830 ℃ for 2 h of heat preservation and pre-calcination. After pre-calcination, grind it to prepare pre-calcined material. (4) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling process is carried out at 500 rpm for 36 h. The slurry is then dried in an oven at 120 ℃ to prepare powder. (5) After passing the powder through a 60-mesh sieve, it was subjected to cold isostatic pressing (pressure 200 MPa, time 5 min) to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank was embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. See the actual ceramic image below. Figure 1 ; The application of the above-mentioned ceramic material for wireless passive temperature sensors in the fabrication of wireless passive temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor is polished into a ceramic disc of 0.8 mm according to the size requirements. Then, a silver layer of 0.1 ± 0.01 mm is plated on both sides of the ceramic disc. Then, it is placed in a sintering furnace at 550 ℃ and sintered for 30 min to produce a silver-plated ceramic disc. The composition of the ceramic material of the aforementioned wireless passive temperature sensor was tested using X-ray diffraction. A standard powder diffraction file (PDF#00-042-0478) was used as a reference sample. The test results are shown below. Figure 2 ; The performance of the silver-plated ceramic discs was tested. The relative permittivity and dielectric loss of the silver-plated ceramic discs were measured at frequencies of 1 kHz, 10 kHz, and 100 kHz within a temperature range of 20–200 °C. The test results are shown below. Figure 3 .

[0028] Example 2: A method for preparing a ceramic material for a wireless passive temperature sensor includes the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.97 Ca 0.01 Sr 0.02 )[(Yb 0.995 In 0.005 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. The raw materials are Yb2O3, Nb2O5, SrCO3, CaO, In2O3 and Pb3O4. (2) Yb2O3 and Nb2O5 were mixed into powder. The powder, zirconia ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to make a slurry. The ball milling speed was 500 rpm and the time was 36 h. The slurry was placed in a 120 ℃ oven to dry. After drying, it was calcined at 1200 ℃ for 4 h and then ground to make YbNbO4 precursor powder. (3) Mix YbNbO4 precursor powder, SrCO3, CaO, In2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powdered zirconia ball mill and anhydrous ethanol at a mass ratio of 1:2:4 and then ball mill to prepare precursor slurry. Place the precursor slurry in an oven at 120 ℃ to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 850 ℃ for 2 h of heat preservation and pre-calcination. After pre-calcination, grind it to prepare pre-calcined material. (4) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling process is carried out at 500 rpm for 36 h. The slurry is then dried in an oven at 120 ℃ to prepare powder. (5) After passing the powder through a 60-mesh sieve, it is subjected to cold isostatic pressing (pressure 200 MPa, time 5 min) to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to form a wireless passive temperature sensor ceramic material. The application of the above-mentioned ceramic material for wireless passive temperature sensors in the fabrication of wireless passive temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor is polished into a ceramic disc of 0.8 mm according to the size requirements. Then, a silver layer of 0.1 ± 0.01 mm is plated on both sides of the ceramic disc. Then, it is placed in a sintering furnace at 550 ℃ and sintered for 30 min to produce a silver-plated ceramic disc. The composition of the ceramic material of the above-mentioned wireless passive temperature sensor was tested by X-ray diffraction, and a standard powder diffraction file was used as a reference sample. The performance of the silver-plated ceramic discs was tested. The relative permittivity and dielectric loss of the silver-plated ceramic discs were tested at frequencies of 1 kHz, 10 kHz and 100 kHz in the temperature range of 20~400 ℃.

[0029] Example 3: A method for preparing a ceramic material for a wireless passive temperature sensor includes the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.94 Ca 0.02 Sr 0.04 )[(Yb 0.992 In 0.004 Lu 0.004 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. The raw materials are Yb2O3, Nb2O5, SrCO3, CaO, In2O3, Lu2O3 and Pb3O4. (2) Yb2O3 and Nb2O5 were mixed into powder. The powder, zirconia ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to make a slurry. The ball milling speed was 500 rpm and the time was 36 h. The slurry was placed in a 120 ℃ oven to dry. After drying, it was calcined at 1200 ℃ for 4 h and then ground to make YbNbO4 precursor powder. (3) Mix YbNbO4 precursor powder, SrCO3, CaO, In2O3, Lu2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powdered zirconia ball mill and anhydrous ethanol at a mass ratio of 1:2:4 and then ball mill to prepare precursor slurry. Place the precursor slurry in a 120 ℃ oven to dry. After drying, pass it through a 60 mesh sieve and then place it in an 850 ℃ heat treatment furnace for 2 h of heat preservation and pre-calcination. After pre-calcination, grind it to prepare pre-calcined material. (4) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling process is carried out at 500 rpm for 36 h. The slurry is then dried in an oven at 120 ℃ to prepare powder. (5) After passing the powder through a 60-mesh sieve, it is subjected to cold isostatic pressing (pressure 200 MPa, time 5 min) to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to form a wireless passive temperature sensor ceramic material. The application of the above-mentioned wireless passive temperature sensor ceramic material in the preparation of wireless passive temperature sensor ceramic materials includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor is polished into a ceramic disc of 0.8 mm according to the size requirements. A platinum layer of 0.1 ± 0.01 mm is deposited on both sides of the ceramic disc using a gold spraying device. Then, it is placed in a sintering furnace at 400 ℃ and sintered for 30 minutes to produce a platinum-plated ceramic disc. The composition of the ceramic material of the above-mentioned wireless passive temperature sensor was tested by X-ray diffraction, and a standard powder diffraction file was used as a reference sample. The performance of the platinum-plated ceramic discs was tested. The relative permittivity and dielectric loss of the platinum-plated ceramic discs were tested at frequencies of 1 kHz, 10 kHz and 100 kHz in the temperature range of 20~200℃.

[0030] Example 4: A method for preparing a ceramic material for a wireless passive temperature sensor includes the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.96Sr 0.04 )[(Yb 0.995 Lu 0.005 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. The raw materials are Yb2O3, Nb2O5, SrCO3, Lu2O3 and Pb3O4. (2) Yb2O3 and Nb2O5 were mixed into powder. The powder, zirconia ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to make a slurry. The ball milling speed was 500 rpm and the time was 36 h. The slurry was placed in a 120 ℃ oven to dry. After drying, it was calcined at 1200 ℃ for 4 h and then ground to make YbNbO4 precursor powder. (3) Mix YbNbO4 precursor powder, SrCO3, Lu2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powdered zirconia ball mill and anhydrous ethanol at a mass ratio of 1:2:4 and then ball mill to make precursor slurry. Place the precursor slurry in an oven at 120 ℃ to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 840 ℃ for 2 h of heat preservation and pre-calcination. After pre-calcination, grind it to make pre-calcined material. (4) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling process is carried out at 500 rpm for 36 h. The slurry is then dried in an oven at 120 ℃ to prepare powder. (5) After passing the powder through a 60-mesh sieve, it is subjected to cold isostatic pressing (pressure 200 MPa, time 5 min) to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 1000 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. The application of the above-mentioned ceramic material for wireless passive temperature sensors in the fabrication of wireless passive temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor was polished into a ceramic disc of 0.8 mm according to the size requirements. A platinum layer of 0.1 ± 0.01 mm was deposited on both sides of the ceramic disc using a gold spraying device. Then, it was placed in a sintering furnace at 550 ℃ and sintered for 30 min to produce a platinum-plated ceramic disc.

[0031] Example 5: A method for preparing a ceramic material for a wireless passive temperature sensor includes the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.97 Ca 0.01 Sr 0.02 )[(Yb0.995 In 0.005 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. The raw materials are Yb2O3, Nb2O5, SrCO3, CaO, In2O3 and Pb3O4. (2) Yb2O3 and Nb2O5 are mixed into powder. The powder, zirconia ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to make a slurry. The ball milling is performed at 500 rpm for 36 h. The slurry is placed in a 120 ℃ oven to dry. After drying, it is calcined at 1200 ℃ for 4 h and then ground to make YbNbO4 precursor powder. (3) Mix YbNbO4 precursor powder, SrCO3, CaO, In2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powdered zirconia ball mill and anhydrous ethanol at a mass ratio of 1:2:4 and then ball mill to prepare precursor slurry. Place the precursor slurry in an oven at 120 ℃ to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 850 ℃ for 2 h of heat preservation and pre-calcination. After pre-calcination, grind it to prepare pre-calcined material. (4) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol are mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling process is carried out at 500 rpm for 36 h. The slurry is then dried in an oven at 120 ℃ to prepare powder. (5) After passing the powder through a 60-mesh sieve, it is subjected to cold isostatic pressing (pressure 200 MPa, time 5 min) to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 1100 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. The application of the above-mentioned wireless passive temperature sensor ceramic material in the fabrication of temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor was polished into a ceramic disc of 0.8 mm according to the size requirements. A platinum layer of 0.1 ± 0.01 mm was deposited on both sides of the ceramic disc using a gold spraying device. Then, it was placed in a sintering furnace at 550 ℃ and sintered for 30 min to produce a platinum-plated ceramic disc.

[0032] Comparative Example 1 Compared with Example 1, Comparative Example 1 uses a one-step synthesis method to prepare ceramic materials for wireless passive temperature sensors, including the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.94 Ca 0.02 Sr 0.04 )[(Yb 0.992In 0.004 Lu 0.004 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. Mix Yb2O3, Nb2O5, SrCO3, Lu2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powder, zirconia ball mill and anhydrous ethanol in a mass ratio of 1:2:4 and then ball mill to prepare a precursor slurry. Place the precursor slurry in a 120 ℃ oven to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 850 ℃ for 2 h for pre-calcination. After pre-calcination, grind it to prepare a pre-calcined material. (2) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling speed was 500 rpm and the time was 36 h. The pre-burned slurry was dried in an oven at 120 ℃ to prepare powder. (3) After passing the powder through a 60-mesh sieve, cold isostatic pressing is applied to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. The application of the above-mentioned wireless passive temperature sensor ceramic material in the fabrication of temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor is ground and polished into a ceramic disc of 0.8 mm according to the size requirements. Then, a silver layer of 0.1 ± 0.01 mm is plated on both sides of the ceramic disc, and then it is placed in a sintering furnace at 550 ℃ for 30 min to produce a silver-plated ceramic disc.

[0033] Comparative Example 2: Compared with Example 2, Comparative Example 2 uses a one-step synthesis method to prepare the ceramic material for the wireless passive temperature sensor, including the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.97 Ca 0.01 Sr 0.02 )[(Yb 0.995 In 0.005 ) 0.5 Nb 0.5Weigh the required raw materials according to the stoichiometric ratio of O3. Mix Yb2O3, Nb2O5, SrCO3, CaO, In2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powder, zirconia ball mill and anhydrous ethanol in a mass ratio of 1:2:4 and then ball mill to prepare a precursor slurry. Place the precursor slurry in an oven at 120 ℃ to dry. After drying, pass it through a 60-mesh sieve and then place it in a heat treatment furnace at 850 ℃ for 2 h for pre-calcination. After pre-calcination, grind it to prepare a pre-calcined material. (2) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling speed was 500 rpm and the time was 36 h. The pre-burned slurry was dried in an oven at 120 ℃ to prepare powder. (3) After passing the powder through a 60-mesh sieve, cold isostatic pressing is applied to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. The application of the above-mentioned wireless passive temperature sensor ceramic material in the fabrication of temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor is ground and polished into a ceramic disc of 0.8 mm according to the size requirements. Then, a silver layer of 0.1 ± 0.01 mm is plated on both sides of the ceramic disc, and then it is placed in a sintering furnace at 550 ℃ for 30 min to produce a silver-plated ceramic disc.

[0034] Comparative Example 3: Compared with Example 3, Comparative Example 3 uses a one-step synthesis method to prepare the ceramic material for the wireless passive temperature sensor, including the following steps: (1) According to the ceramic material of the wireless passive temperature sensor (Pb 0.94 Ca 0.02 Sr 0.04 )[(Yb 0.992 In 0.004 Lu 0.004 ) 0.5 Nb 0.5 Weigh the required raw materials according to the stoichiometric ratio of O3. Mix Yb2O3, Nb2O5, SrCO3, CaO, In2O3, Lu2O3 and Pb3O4 into powder. Pb3O4 needs to be in excess (an additional 2 wt% of Pb3O4 is weighed). Mix the powder, zirconia ball mill and anhydrous ethanol in a mass ratio of 1:2:4 and then ball mill to prepare a precursor slurry. Place the precursor slurry in a 120 ℃ oven to dry. After drying, pass it through a 60 mesh sieve and then place it in a heat treatment furnace at 850 ℃ for 2 h for pre-calcination. After pre-calcination, grind it to prepare a pre-calcined material. (2) The pre-burned material, zirconium oxide ball mill and anhydrous ethanol were mixed in a mass ratio of 1:2:4 and then ball milled to prepare a pre-burned slurry. The ball milling speed was 500 rpm and the time was 36 h. The pre-burned slurry was dried in an oven at 120 ℃ to prepare powder. (3) After passing the powder through a 60-mesh sieve, cold isostatic pressing is applied to form a cylindrical blank with a diameter of 10 mm and a thickness of 1.5 mm; the blank is embedded in the master powder and sintered in a sintering furnace at 950 ℃ for 4 h to produce a wireless passive temperature sensor ceramic material. The application of the above-mentioned wireless passive temperature sensor ceramic material in the fabrication of temperature sensors includes the following steps: The ceramic material of the above-mentioned wireless passive temperature sensor was polished into a ceramic disc of 0.8 mm according to the size requirements. A platinum layer of 0.1 ± 0.01 mm was deposited on both sides of the ceramic disc using a gold spraying device. Then, it was placed in a sintering furnace at 400 ℃ and sintered for 30 min to produce a platinum-plated ceramic disc.

[0035] Comparative Example 4: Compared to the examples, Comparative Example 4 used PDC-SiBCN ceramic.

[0036] like Figure 2 As shown, the diffraction pattern of the wireless passive temperature sensor ceramic material prepared in Example 1 is consistent with the diffraction pattern of the standard powder diffraction file, and there are no impurity phases. The wireless passive temperature sensor ceramic materials prepared in Comparative Examples 1, 2, and 3 are prone to exhibiting pyrochlore impurity phases. The above results indicate that the preparation method of the present invention, which first synthesizes the YbNbO4 precursor and then synthesizes the YbNbO4 precursor with other materials to form the wireless passive temperature sensor ceramic material, can avoid the problem of pyrochlore impurity phases in the ceramic. Pyrochlore impurities weaken the ceramic performance; therefore, compared with the one-step synthesis method, the method of the present invention can improve the performance of the wireless passive temperature sensor ceramic material.

[0037] like Figure 3 As shown, the dielectric properties of the temperature sensor made of ceramic material obtained in Example 1 were tested. The test results show that the relative permittivity ranges from 95.4 to 136.8 in the temperature range of 20 to 200 °C, the nonlinear error is 5.2%, the sensitivity is 0.22% / ℃, it remains stable in the frequency range of 1 to 100 kHz, and the dielectric loss is less than 0.04.

[0038] The dielectric properties of the wireless passive temperature sensor made of ceramic material obtained in Example 2 were tested. The test results showed that the relative permittivity ranged from 95.8 to 137.5 in the temperature range of 20 to 200 °C, the nonlinear error was 5.5%, the sensitivity was 0.23% / ℃, it remained stable in the frequency range of 1 to 100 kHz, and the dielectric loss was less than 0.04.

[0039] The dielectric properties of the wireless passive temperature sensor made of ceramic material prepared in Example 3 were tested. The test results showed that the relative permittivity ranged from 95.5 to 136.6 in the temperature range of 20 to 200 °C, the nonlinear error was 5%, the sensitivity was 0.22% / ℃, it remained stable in the frequency range of 1 to 100 kHz, and the dielectric loss was less than 0.04.

[0040] The dielectric properties of the wireless passive temperature sensor made of ceramic material prepared in Comparative Example 4 were tested. The test results showed that the relative permittivity ranged from 4 to 7 in the temperature range of -50 to 150 ℃, the nonlinear error was 3 to 5%, the sensitivity was 0.02 to 0.03% / ℃, it remained stable in the frequency range of 1 to 100 kHz, and the dielectric loss was less than 0.01.

[0041] Comparing the results of Examples 1-3 and Comparative Example 4, it can be seen that the dielectric constant of the ceramic of the present invention increases from 80-96 to 136-200 within the range of 20-200 °C, and the corresponding resonant frequency decreases by about 17-20% with increasing temperature. Compared with PDC-SiBCN ceramic, the ceramic prepared by the present invention has a wider operating temperature range (20-200 °C / 50-150 °C), a larger amplitude of resonant frequency change (17-20% / 5-8%), and higher sensitivity (0.22-0.23% / ℃ / 0.02-0.03% / ℃). The extremely high sensitivity range is 20-200 °C, and the sensitivity reaches 0.22-0.23% / ℃, which meets the requirements of high temperature, high sensitivity, and high linearity scenarios.

[0042] The above results indicate that the three wireless passive temperature sensor ceramic materials (Pb) provided by this invention... 0.96 Sr 0.04 )[(Yb 0.995 Lu 0.005 ) 0.5 Nb 0.5 O3、(Pb) 0.97 Ca 0.01 Sr 0.02 )[(Yb 0.995 In 0.005 ) 0.5 Nb 0.5 O3 and (Pb)0.94 Ca 0.02 Sr 0.04 )[(Yb 0.992 In 0.004 Lu 0.004 ) 0.5 Nb 0.5 Temperature sensors made of O3 exhibit high sensitivity and high linearity at operating temperatures ranging from 20 to 200 °C. They combine a wide operating temperature range with high sensitivity and high linearity. Furthermore, these ceramic temperature sensors have stable dielectric constants and low dielectric losses at frequencies from 1 to 100 kHz. Therefore, this ceramic can be used in wireless passive temperature sensors that measure the resonant frequency of resonant cavities.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A wireless passive temperature sensor ceramic material, characterized in that, The chemical composition is (Pb1-xAx)[(Yb1-yBy)0.5Nb0.5]O3, where A is one of Ca and Sr, B is one of In and Lu, 0 < x ≤ 0.06, and 0 < y ≤ 0.

01.

2. A method of producing the wireless passive temperature sensor ceramic material according to claim 1, characterized in that Includes the following steps: (1) Yb2O3 and Nb2O5 were ball-milled to form a slurry, and the slurry was dried and calcined to form a YbNbO4 precursor; (2) YbNbO4 precursor, Pb3O4 and other oxide raw materials were ball-milled to prepare a precursor slurry. The precursor slurry was then dried, sieved and... Pre-fired to produce pre-fired material; (3) The pre-fired material is ball-milled to make a pre-fired slurry, and the pre-fired slurry is dried to make a powder. (4) Press the powder into a blank, and sinter the blank to make a lead ytterbium niobate-based dielectric ceramic with a permittivity that changes linearly with temperature.

3. The method of claim 2, wherein the method further comprises, The calcination temperature is 1200~1300 ℃.

4. The production method according to claim 2 or 3, characterized by, The calcination time is 4-5 hours.

5. The preparation method according to claim 2, characterized in that, The preheating temperature is 830~850 ℃.

6. The production method according to claim 2 or 5, characterized by, Preheating time is 3-4 hours.

7. The preparation method according to claim 2, characterized in that, The ball milling process was performed using zirconia ball mills and anhydrous ethanol.

8. The method of claim 2, wherein the method further comprises, Other oxide raw materials include strontium carbonate, lutetium oxide, calcium oxide, and indium oxide. One or more of the following.

9. The method of claim 2, wherein the method further comprises, The sintering temperature is 900~1100 ℃, and the sintering time is 2~4 h.

10. The method of claim 2 wherein the step of forming the first and second layers comprises the step of: The pressing is performed using cold isostatic pressing, with a pressure of 200~220 MPa and a time of 5~8 minutes. ​

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