CN116621579B - High-precision thermistor material suitable for wide temperature range temperature measurement and preparation method thereof - Google Patents

Abstract

The invention relates to a high-precision thermistor material suitable for wide temperature range temperature measurement and a preparation method thereof, the material takes cerium oxide, neodymium oxide, samarium oxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide as raw materials, the chemical composition is Ce _1‑2x(NdSm)_x(VNbTa)_1/3O₄, wherein x is more than or equal to 0 and less than or equal to 1/3, and the material constant is B _{200℃/600℃} =4633K-5689K after mixed grinding, presintering, cold isostatic pressing, high-temperature sintering and electrode coating, the linear fitting Pearson's r coefficient of the material with the resistivity of 1.04 multiplied by 10 ⁷-1.78×10⁵ Ω cm, ln rho and 1000/T at the temperature of 150 ℃ is more than or equal to 999.57%, the resistivity drift rate after aging at the temperature of 600 ℃ for 1000 hours is less than or equal to 2.6%, the thermistor material has stable performance, good consistency and obvious negative temperature coefficient characteristics in a wide temperature range of-50-550 ℃, and is suitable for manufacturing the high-precision thermistor suitable for wide temperature range temperature measurement.

Description

High-precision thermistor material suitable for wide temperature range temperature measurement and preparation method thereof

Technical Field

The invention relates to a high-precision thermistor material suitable for measuring temperature in a wide temperature range and a preparation method thereof.

Background Art

High-entropy ceramics have attracted increasing interest in a wide range of fields due to their unique structural features and interesting functional properties triggered by entropy engineering, which brings opportunities to adjust the composition, microstructure and properties of oxide ceramics. Recent reports show that high-entropy oxide ceramics actually have a high density of dislocations (about 10 ⁹ mm ^-2 ), and importantly, the high density of dislocations is thermodynamically stable because the configurational entropy gain can compensate for the large strains caused by rigid ionic/covalent bonds in oxide ceramics. Establishing stable high-density dislocations in oxide ceramics will bring unprecedented opportunities for adjusting the mechanical, chemical, electrical and transport properties of oxide ceramics.

The high entropy effect is very important in high entropy ceramics. On the one hand, they can maintain a single phase under extreme temperatures, pressures and chemical environments, and show excellent stability and resilience in various applications. On the other hand, they can form dislocation-based local plasticity zones and become additional toughening mechanisms in bulk ceramics to solve the brittleness problem that has always restricted the widespread application of ceramics. Of course, the changes brought about by the high entropy effect to the oxide ceramics neighborhood are far more than that. For NTC thermistors, high configuration entropy improves the overall stability of the ceramics, and high-density dislocations also have a rare inhibitory effect on the transport of oxygen ions. In some oxide ceramics, high-density dislocations can form a diffusion barrier shrouded near the grain boundary, inhibiting the diffusion of oxygen ions from the grain boundary to the interior. This will help solve the complex and diverse phenomena of multivalent metal cations in NTC thermistors, especially the complex oxygen non-stoichiometric behavior caused by the temperature dependence of cation charge disproportionation.

Dislocations in ionic solids are topologically extended defects that regulate composition, strain, and charge at multiple length scales. Therefore, they provide additional degrees of freedom to tailor ion and electron transport beyond the inherent limitations of bulk doping. The optimization of NTC thermistors by high-density dislocations is foreseeable, and the solution to the temperature-dependent oxygen non-stoichiometric behavior will help to break through the performance of thermistors and enhance the application prospects of NTC thermistors in the field of temperature sensors. _{CeNbO 4+δ} is a mixed electron-oxygen ion conductive material with good negative temperature coefficient thermistor properties. Moreover, the dislocation density in the ceramic material is regulated by the configuration entropy strategy to suppress the conductivity of oxygen ions, thereby changing the adverse effects of oxygen ion conduction in the material on the ceramic. In this way, the electrical transport properties and high-temperature stability of CeNbO _4+δ ceramics can be regulated by the configuration entropy strategy.

Summary of the invention

The object of the present invention is to provide a high-precision thermistor material suitable for wide temperature range temperature measurement and a preparation method thereof. The material is made of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide as raw materials, and through mixed grinding, pre-sintering, cold isostatic pressing, high-temperature sintering and electrode coating, a material constant B _{200°C/600°C} = 4633K-5689K is obtained, the resistivity is 1.04×10 ⁷ -1.78×10 ⁵ Ω.cm at a temperature of 150°C, the linear fitting Pearson's r coefficient of lnρ and 1000/T is ≥999.57‰, and the resistance drift rate is ≤2.6% after aging at a temperature of 600°C for 1000 hours. The thermistor material has stable performance and good consistency, has obvious negative temperature coefficient characteristics in a wide temperature range of -50-550°C, and is suitable for manufacturing high-temperature thermistors.

The invention discloses a high-precision thermistor material suitable for wide temperature range temperature measurement. The thermistor material uses cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide as raw materials, and has a chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , wherein 0≤x≤1/3. The structure of the resistor material exhibits a tetragonal scheelite structure when 0≤x≤1/12, and exhibits a monoclinic yttrium niobate structure when 1/3≥x>1/12. The specific operation is performed according to the following steps:

a. According to the chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide are weighed respectively according to 0≤x≤1/3, mixed and ground in an agate mortar for 7-9 hours, then calcined at a temperature of 900-1000°C for 3-5 hours, and ground again for 7-9 hours to obtain dispersed single-phase Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 15-25 Kg/ ^cm2 for 3-5 minutes, and the formed block material is cold isostatically pressed at a pressure of 250-350 MPa for 3-5 minutes, and then sintered at a temperature of 1100-1200°C for 10-14 hours to obtain a disc-shaped high-density ceramic block material of _Ce1-2x (NdSm) _x (VNbTa) _{1/ 3O4} ;

c. Coat the front and back sides of the disc-shaped high-density ceramic block material sintered in step b with platinum slurry electrodes, and then continue annealing at a temperature of 900°C for 50 hours to obtain a wide temperature range high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 4633K-5689K, and a linear fitting Pearson's r coefficient of lnρ and 1000/T of ≥999.57‰.

A method for preparing a high-precision thermistor material suitable for wide temperature range temperature measurement is carried out according to the following steps:

a. According to the chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide are weighed respectively according to 0≤x≤1/3, mixed and ground in an agate mortar for 7-9 hours, then calcined at a temperature of 900-1000°C for 3-5 hours, and ground again for 7-9 hours to obtain dispersed single-phase Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 15-25 Kg/ ^cm2 for 3-5 minutes, and the formed block material is cold isostatically pressed at a pressure of 200-350 MPa for 3-5 minutes, and then sintered at a temperature of 1100-1200°C for 10-14 hours to obtain a disc-shaped high-density ceramic block material of _Ce1-2x (NdSm) _x (VNbTa) _{1/ 3O4} ;

c. Coat the front and back sides of the disc-shaped high-density ceramic block material in step b with platinum slurry electrodes, and then continue annealing at a temperature of 900°C for 50 hours to obtain a high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 4633K-5689K, a resistivity of 1.04×10 ⁷ -1.78×10 ⁵ Ω.cm at a temperature of 150°C, a linear fitting Pearson'sr coefficient of lnρ and 1000/T of ≥999.57‰, and a resistance drift rate of ≤2.6% after aging at a temperature of 600°C for 1000 hours.

The invention discloses a high-precision thermistor material suitable for measuring temperature in a wide temperature range and a preparation method thereof. The material can be used to manufacture a high-precision thermistor in a wide temperature range.

The invention discloses a high-precision thermistor material suitable for measuring temperature in a wide temperature range and a preparation method thereof. The thermistor material uses cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide as raw materials, and has a chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ . The raw materials are weighed according to 0≤x≤1/3, and the high-precision thermistor material suitable for measuring temperature in a wide temperature range is obtained through mixed grinding, calcination, cold isostatic pressing, high-temperature sintering and electrode coating. At the same time, the content of Ce ions in CeNbO ₄ can be adjusted to adjust the electrical properties of the Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ system thermistor material, so as to manufacture a thermistor with adjustable electrical properties.

The present invention starts from the semiconductor properties of _CeNbO4 thermistor materials and designs and synthesizes high-stability _Ce1-2x (NdSm) _x (VNbTa) _{1/ 3O4} thermistor materials that can be used in the temperature range of -50-550℃ through a high entropy configuration strategy.

Beneficial effects: Compared with the prior art, the present invention has the following advantages:

The invention discloses a high-precision thermistor material suitable for wide temperature range temperature measurement and a preparation method thereof. The thermistor material has an obvious negative temperature coefficient characteristic in the temperature range of -50-550°C, the linear fitting Pearson's r coefficients of lnρ and 1000/T are both ≥999.57‰, and the resistance drift rate after aging at 600°C for 1000 hours is ≤2.6%. The thermistor material is a new type of high-precision thermistor material suitable for manufacturing thermistors in a wide temperature range.

The invention discloses a high-precision thermistor material suitable for measuring temperature in a wide temperature range and a preparation method thereof. The solid phase method is adopted to use oxides of cerium, neodymium, samarium, vanadium, niobium and tantalum as raw materials. The chemical composition is Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , wherein 0≤x≤1/3. The oxides are weighed and mixed, ground, calcined and mixed respectively. The powder materials are ground again to obtain a negative temperature coefficient thermistor powder material. The powder materials are then pressed into blocks, cold isostatically pressed, sintered at high temperature, and then coated with platinum slurry electrodes on both sides to obtain a high-temperature multi-component single-phase solid solution thermistor material. The thermistor material constant is B _{200°C/600°C} =4633K-5689K. The resistivity at a temperature of 150°C is 1.04×10 ⁷ -1.78×10 ⁵ Ω.cm. The linear fitting of lnρ and 1000/T is Pearson's The r coefficient is ≥999.57‰, and the resistance drift rate is ≤2.6% after aging at 600℃ for 1000 hours. It has the advantages of stable performance, high precision, high sensitivity, and good consistency. The thermistor material has excellent negative temperature coefficient characteristics in a wide temperature range of -50-550℃, and is suitable for manufacturing high-performance thermistors. The specific performance parameters are shown in Table 1;

Table 1

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an X-ray diffraction pattern of the thermistor material of the present invention (without platinum paste electrode coating).

FIG. 2 is a resistance-temperature characteristic curve of the thermistor of the present invention.

DETAILED DESCRIPTION

Example 1 (x=0)

a. According to the composition of Ce(VNbTa) _1/3 O ₄ , weigh the raw materials of cerium dioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide respectively, put them in an agate mortar and grind them together for 7 hours, then calcine them at a temperature of 900°C for 5 hours, and grind them again for 9 hours to obtain dispersed single-phase Ce(VNbTa) _1/3 O ₄ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 15 Kg/ ^cm2 for 5 minutes, the formed block material is cold isostatically pressed at a pressure of 250 MPa for 5 minutes, and then sintered at a temperature of 1100°C for 14 hours to obtain a high-temperature thermistor ceramic material;

c. Coating the material sintered in step b with platinum slurry electrodes on both sides, and then annealing at 600°C for 50 hours to obtain a high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 4633K, a resistivity of 1.13×10 ⁶ Ω.cm at 150°C, and a linear fitting Pearson's r coefficient of lnρ and 1000/T of 999.57‰;

After aging for 1000 hours at 600°C, the absolute value of the resistance deviation is less than 2.60%.

Example 2 (x=1/12)

a. According to the composition of Ce _5/6 (NdSm) _1/12 (VNbTa) _1/3 O ₄ , raw materials of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide were weighed respectively, mixed and ground in an agate mortar for 7.5 hours, then calcined at 900°C for 4.5 hours, and ground again for 8.5 hours to obtain dispersed single-phase Ce _5/6 (NdSm) _1/12 (VNbTa) _1/3 O ₄ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 17.5 Kg/ ^cm2 for 3.5 minutes, the formed block material is cold isostatically pressed at a pressure of 275 MPa for 4.5 minutes, and then sintered at a temperature of 1125°C for 13 hours to obtain a disc-shaped high-density ceramic block material;

c. Coating the front and back sides of the disc-shaped high-density ceramic block material sintered in step b with platinum slurry electrodes, and then continuously annealing at a temperature of 900°C for 50 hours to obtain a wide temperature range high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 4808K, a resistivity of 2.56×10 ⁵ Ω.cm at a temperature of 150°C, and a linear fitting Pearson's r coefficient of lnρ and 1000/T of 999.91‰;

After aging for 1000 hours at 600°C, the absolute value of the resistance deviation is less than 1.21%.

Example 3 (x=1/6)

a. According to the composition of Ce _2/3 (NdSm) _1/6 (VNbTa) _1/3 O ₄ , raw materials of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide were weighed respectively, mixed and ground in an agate mortar for 8 hours, then calcined at a temperature of 950°C for 4 hours, and ground again for 8 hours to obtain dispersed single-phase Ce _2/3 (NdSm) _1/6 (VNbTa) _1/3 O ₄ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 30 Kg/ ^cm2 for 4 minutes, the formed block material is cold isostatically pressed at a pressure of 300 MPa for 4 minutes, and then sintered at a temperature of 1150°C for 12 hours to obtain a disc-shaped high-density ceramic block material;

c. Coating the material sintered in step b with platinum paste electrodes on both sides, and then annealing at 900°C for 50 hours to obtain a high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 4921K, a resistivity of 4.20×10 ⁵ Ω.cm at 150°C, and a linear fitting Pearson's r coefficient of 999.99‰ for lnρ and 1000/T;

After aging for 1000 hours at 600°C, the absolute value of the resistance deviation is less than 0.79%.

Example 4 (x=1/4)

a. According to the composition of Ce _1/2 (NdSm) _1/4 (VNbTa) _1/3 O ₄ , raw materials of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide were weighed respectively, mixed and ground in an agate mortar for 7 hours, then calcined at a temperature of 975°C for 5 hours, and ground again for 7 hours to obtain dispersed single-phase Ce _1/2 (NdSm) _1/4 (VNbTa) _1/3 O ₄ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 25 Kg/ ^cm2 for 4.5 minutes, the formed block material is cold isostatically pressed at a pressure of 200 MPa for 3.5 minutes, and then sintered at a temperature of 1175°C for 10 hours to obtain a disc-shaped high-density ceramic block material;

c. Coating the material sintered in step b with platinum paste electrodes on both sides, and then annealing at 600°C for 50 hours to obtain a high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 5108K, a resistivity of 1.33×10 ⁶ Ω.cm at 150°C, and a linear fitting Pearson's r coefficient of 999.99‰ for lnρ and 1000/T;

After aging for 1000 hours at 600°C, the absolute value of the resistance deviation is less than 0.52%.

Example 5 (x=1/3)

a. According to the molar ratio of (CeNdSm) _1/3 (VNbTa) _1/3 O ₄ , the raw materials of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide are weighed respectively, placed in an agate mortar and mixed and ground for 9 hours, then calcined at a temperature of 1000°C for 3 hours, and ground again for 9 hours to obtain a dispersed single-phase (CeNdSm) _1/3 (VNbTa) _1/3 O ₄ powder;

b. The powder material obtained in step a is pressed into blocks at a pressure of 15 Kg/ ^cm2 for 5 minutes, the formed block material is cold isostatically pressed at a pressure of 350 MPa for 3 minutes, and then sintered at a temperature of 1200°C for 14 hours to obtain a disc-shaped high-density ceramic block material;

c. Coating the material sintered in step b with platinum paste electrodes on both sides, and then annealing at 900°C for 50 hours to obtain a high-precision thermistor material with a temperature range of -50-550°C, a material constant of B _{200°C/600°C} = 5689K, a resistivity of 1.04×10 ⁷ Ω.cm at 150°C, and a linear fitting Pearson's r coefficient of lnρ and 1000/T of 999.85‰;

After aging for 1000 hours at 600°C, the absolute value of the resistance deviation is less than 0.23%.

The above are only specific implementations of the present invention, but the design concept of the present invention is not limited thereto.

Claims (2)

1. A high-precision thermistor material suitable for wide temperature range temperature measurement, characterized in that the thermistor material is made of cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide as raw materials, and its chemical composition is Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , wherein 0≤x≤1/3, the structure of the resistor material exhibits a tetragonal scheelite structure when 0≤x≤1/12, and exhibits a monoclinic yttrium niobate structure when 1/3≥x>1/12, and the specific operation is carried out according to the following steps: a. According to the chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide are weighed respectively according to 0≤x≤1/3, mixed and ground in an agate mortar for 7-9 h, then calcined at a temperature of 900-1000°C for 3-5 h, and ground again for 7-9 h to obtain dispersed single-phase Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ powder; b. The powder material obtained in step a is pressed into blocks at a pressure of 15-25 Kg/ ^cm2 for 3-5 minutes, and the formed block material is cold isostatically pressed at a pressure of 250-350 MPa for 3-5 minutes, and then sintered at a temperature of 1100-1200°C for 10-14 hours to obtain a disc-shaped high-density ceramic block material of _Ce1-2x (NdSm) _x (VNbTa) _{1/ 3O4} ; c. Coat the front and back sides of the disc-shaped high-density ceramic block material sintered in step b with platinum slurry electrodes, and then continuously anneal at a temperature of 900°C for 50 hours to obtain a wide temperature range high-precision thermistor material with a temperature range of -50 – 550°C, a material constant of B _{200°C/600°C} = 4633 K-5689 K, and linear fitting Pearson's r coefficients of ln ρ and 1000/ T both ≥999.57‰. 2. A method for preparing a high-precision thermistor material suitable for wide temperature range temperature measurement, characterized by the following steps: a. According to the chemical composition of Ce _1-2x (NdSm) _x (VNbTa) _1/3 O ₄ , cerium dioxide, neodymium trioxide, samarium trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide are weighed respectively according to 0≤x≤1/3, mixed and ground in an agate mortar for 7-9 h, then calcined at a temperature of 900-1000°C for 3-5 h, and ground again for 7-9 h to obtain dispersed single-phase Ce _1-2x (NdSm) _x (VNbTa) _1/3 O _4+δ powder; b. The powder material obtained in step a is pressed into blocks at a pressure of 15-25 Kg/ ^cm2 for 3-5 minutes, and the formed block material is cold isostatically pressed at a pressure of 200-350 MPa for 3-5 minutes, and then sintered at a temperature of 1100-1200°C for 10-14 hours to obtain a disc-shaped high-density ceramic block material of _Ce1-2x (NdSm) _x (VNbTa) _{1/ 3O4} ; c. Coat the front and back sides of the disc-shaped high-density ceramic block material in step b with platinum slurry electrodes, and then anneal for 50 hours at 900°C to obtain a high-precision thermistor material with a temperature range of -50 - 550°C, a material constant of B _{200°C/600°C} = 4633 K-5689 K, a resistivity of 1.04×10 ⁷ -1.78×10 ⁵ Ω.cm at 150°C, a linear fitting Pearson'sr coefficient of ln ρ and 1000/ T of ≥999.57 ‰, and a resistance drift rate of ≤2.6% after aging at 600°C for 1000 hours.