Chip type piezoresistor and method for manufacturing the same

Abstract

The application relates to the technical field of preparation of pressure-sensitive resistors, in particular to a chip pressure-sensitive resistor and a preparation method thereof. The chip pressure-sensitive resistor is prepared by sintering a zinc oxide pressure-sensitive ceramic composition; the zinc oxide pressure-sensitive ceramic composition is composed of main materials and a dopant, the dopant accounts for 2-10 wt% of the total mass of the zinc oxide pressure-sensitive ceramic composition; the main materials are a compound of nano-zinc oxide and single-atom modified zinc oxide or the main materials are single-atom modified zinc oxide; the dopant is at least one of Bi2O3, Sb2O3, Cr2O3, Co2O3, CoO, MnO2, Mn2O3, NiO, CuO, TiO2, Al2O3, SiO2, Fe2O3 and La2O3. The chip pressure-sensitive resistor prepared by the application has high nonlinearity coefficient and excellent stability, and solves the problem of relatively poor nonlinearity of the zinc oxide pressure-sensitive resistor produced by the existing solid-phase mechanical mixing method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of piezoresistor preparation, and particularly relates to a chip piezoresistor and a preparation method thereof. BACKGROUND

[0002] The piezoresistor is a semiconductor ceramic element formed by sintering zinc oxide as a main raw material and other group II-VI oxides (Bi2O3, Sb2O3, Co2O3, CoO, Cr2O3, MnO2, Mn2O3, etc.), which has excellent nonlinear ohmic characteristics, strong transient energy absorption capacity, short response time and other advantages, and is widely used in power systems, electronic circuits, microelectronic circuits and other fields as an overvoltage protector. The zinc oxide piezoceramic has unique voltage-current characteristics, can maintain very small conductivity (equivalent to insulating material) under low voltage, and has very high conductivity and dielectric constant under high voltage, that is, has high nonlinearity in the conductive state and low leakage current under the steady-state working voltage, thereby playing a role in overvoltage protection.

[0003] The zinc oxide in the zinc oxide piezoceramic formula is a non-stoichiometric n-type semiconductor, and the voltage-current characteristics thereof are linear. The intrinsic defects of zinc oxide include oxygen vacancies and zinc interstitial atoms, and these defects cause the zinc oxide to exhibit n-type conductivity. In addition, impurities (such as hydrogen, nitrogen, etc.) in the zinc oxide also have adverse effects on the electrical properties.

[0004] At present, the preparation method of the zinc oxide piezoresistor is mainly the solid-phase mechanical mixing method, which has the advantages of simple preparation process, low preparation cost and other industrial production advantages. The existing solid-phase mechanical mixing method is prepared by ball milling, mixing, molding and sintering of zinc oxide particles and a small amount of group II-VI oxides in a solid state. The uniform distribution of zinc oxide and group II-VI oxides is relatively poor compared with the zinc oxide piezoresistor prepared by chemical co-precipitation method and ultrasonic emulsion co-precipitation method, which directly leads to relatively poor nonlinearity of the prepared zinc oxide piezoresistor. The zinc oxide piezoresistor prepared by the chemical co-precipitation method and the ultrasonic emulsion co-precipitation method cannot meet the requirements of industrial production due to the problems of difficult process control, low yield and high cost. Therefore, the inventors have conducted in-depth research on the uniform distribution of zinc oxide and group II-VI oxides, and provided a chip piezoresistor with high nonlinearity coefficient and a preparation method thereof. SUMMARY

[0005] In order to solve the technical problem of relatively poor nonlinearity of the zinc oxide piezoresistor produced by the existing solid-phase mechanical mixing method, the present application provides a chip piezoresistor and a preparation method thereof. By refining the particle size of zinc oxide and group II-VI oxides and performing single-atom surface modification on the zinc oxide containing intrinsic defects, the prepared chip zinc oxide piezoresistor has high nonlinearity coefficient and excellent stability.

[0006] The sheet type piezoresistor is prepared by the following technical scheme.

[0007] The sheet type piezoresistor is prepared by sintering a zinc oxide piezoceramic composition; the zinc oxide piezoceramic composition is composed of a main material and a dopant, the dopant accounts for 2-10 wt% of the total mass of the zinc oxide piezoceramic composition; the main material is a compound of nano-zinc oxide and monatomic modified zinc oxide or the main material is monatomic modified zinc oxide; the dopant is at least one of Bi2O3, Sb2O3, Cr2O3, Co2O3, CoO, MnO2, Mn2O3, NiO, CuO, TiO2, Al2O3, SiO2, Fe2O3 and La2O3.

[0008] The zinc oxide containing intrinsic defects is subjected to monatomic surface modification treatment, which improves the compatible dispersibility of the II-VI group oxides and reduces the intrinsic defects of the zinc oxide after the monatomic surface modification, so that the conductivity, heat conductivity and stability of the zinc oxide are improved; the sheet type piezoresistor prepared by using the monatomic modified zinc oxide has high nonlinearity coefficient and excellent stability, and solves the problem of relatively poor nonlinearity of the zinc oxide piezoresistor prepared by the existing solid-phase mechanical mixing method.

[0009] Preferably, the monatomic modified zinc oxide comprises nano-zinc oxide and metal monatomic anchored to defect points on the surface of the nano-zinc oxide, the nano-zinc oxide is n-type zinc oxide with a particle size of ≤500 nm, the metal monatomic is one or a combination of Bi, Sb, Cr, Co, Mn, Ni, Ti, Cu, Al, Fe and La, and the mass ratio of the nano-zinc oxide to the metal monatomic is (20-100):1.

[0010] Preferably, the mass ratio of the nano-zinc oxide to the metal monatomic is (40-60):1.

[0011] Preferably, the metal monatomic is Bi, Sb, La or the metal monatomic is Bi, Sb, La in combination with at least one of Cr, Co, Mn, Ni, Ti, Cu, Al and Fe.

[0012] Further preferably, the metal monatomic is Bi, Sb, Co, Mn and La, and the mass ratio of Bi, Sb, Co, Mn and La in the metal monatomic is 1:1:1:1:(0.1-1).

[0013] The surface of zinc oxide is modified by Bi, Sb and La as main metal single atoms, Bi, Sb and La are anchored on the defect points of the surface of nano zinc oxide in the form of covalent bond, when the n-p junction effect is formed by the ZnO crystal grain-bismuth-rich grain boundary-ZnO crystal grain in the disc type piezoresistor prepared by the single atom surface modified zinc oxide, the bismuth-rich layer can be more uniformly formed during the sintering of the single atom surface modified zinc oxide crystal grain, and the Sb, Co, Mn and La atoms contained on the surface of the bismuth-rich layer, so that the bismuth-rich layer is uniformly doped with relatively more Sb, Co, Mn and La during the sintering process, the height of the grain boundary barrier is improved, and the nonlinear coefficient of the whole is improved.

[0014] Preferably, the preparation method of the single atom modified zinc oxide comprises the following steps:

[0015] Step one, the nano zinc oxide is placed in a 5-20wt% tartaric acid aqueous solution for ultrasonic dispersion treatment for 1-4h, and then reduced pressure filtration, washing and vacuum drying are carried out to obtain carrier zinc oxide;

[0016] Step two, the metal single atom precursor is prepared: the water-soluble metal salt is added to high-purity water, and then magnetic stirring is carried out for 0.5-2h, and then ultrasonic dispersion treatment is carried out for 0.5-1h, so that the water-soluble metal salt is fully dissolved to obtain the metal single atom precursor;

[0017] Step three, under magnetic stirring, the carrier zinc oxide in step one is added to the metal single atom precursor in step two at a feeding speed of 0.05-0.5g / min, and the mass ratio of the carrier zinc oxide to the metal single atom in the metal single atom precursor is (20-100) : 1, after the feeding of the carrier zinc oxide is completed, magnetic stirring is continued for 4-24h, and then ultrasonic dispersion treatment is carried out for 1-4h, and then rotary evaporation is carried out at 80-100 DEG C to remove water, and then vacuum drying is carried out to obtain a solid material;

[0018] Step four, the solid material is subjected to wet planetary ball milling to obtain superfine powder, and then the obtained superfine powder is calcined at 400-600 DEG C for 4-12h, and then planetary ball milling is carried out to obtain the required single atom modified zinc oxide.

[0019] Preferably, the water-soluble metal salt is any one or a combination of multiple of chlorides, nitrates, sulfates, acetates and acetylacetone salts.

[0020] The preparation method of the single atom modified zinc oxide in the application is relatively simple and mature, and the production cost of the single atom modified zinc oxide can be reduced, so that the performance advantage of the disc type piezoresistor can be improved.

[0021] Preferably, the zinc oxide varistor ceramic composition is made from the following raw materials in mass percentage: 1-2% Bi2O3, 1-2.5% Sb2O3, 0.5-1% Cr2O3, 0.6-1.2% Co2O3, 0.6-1.2% Mn2O3, 0.5-1% NiO, 0.01-0.10% La2O3, and the rest is monatomic modified zinc oxide.

[0022] By optimizing the selection of the dopant in the zinc oxide varistor ceramic composition, the chip varistor is endowed with higher nonlinear coefficient and energy absorption capacity, lower leakage current, and improved overall piezoelectric performance and high safety and reliability.

[0023] The application provides a preparation method of a chip varistor.

[0024] The preparation method of the chip varistor comprises the following steps:

[0025] Step one, preparation of monatomic modified zinc oxide;

[0026] Step two, accurately metered main materials and dopants are mixed according to the proportion to obtain a mixture, the mixture is placed in a planetary ball mill for wet ball milling, the solid-liquid ratio is 1:10-40, a dispersing agent is pure water or an ethanol aqueous solution, wet ball milling is performed for 2-8 h under nitrogen protection, and then the zinc oxide varistor ceramic composition is prepared through filtration, washing, and vacuum drying;

[0027] Step three, 100 parts by weight of the zinc oxide varistor ceramic composition is mixed with 6-8 parts by weight of a binder and then placed in a disc granulator for granulation treatment, and the varistor ceramic granules are obtained through screening through a 50-120 mesh screen;

[0028] Step four, the varistor ceramic granules in step three are put into a mold for dry pressing to obtain a sheet-shaped pressing sample, the sheet-shaped pressing sample is placed in a muffle furnace for sintering treatment, and the sheet-shaped pressing sample is cooled to room temperature to obtain the chip varistor.

[0029] Preferably, in step four, the varistor ceramic granules in step three are put into a mold for dry pressing at a pressure of 200±20 MPa and a pressure maintaining time of 60-120 s to obtain the sheet-shaped pressing sample, the sheet-shaped pressing sample is placed in a muffle furnace for sintering treatment, and the sintering treatment program is as follows: the temperature is raised to 550-650 ℃ at a rate of 200-300 ℃ / h, the glue is removed for 30-45 min, then the temperature is raised to 850-900 ℃ at a rate of 400-600 ℃ / h, the temperature is raised to 1150-1250 ℃ at a rate of 1000-1200 ℃ / h and is kept for 2-4 h, the temperature is lowered to 850-900 ℃ at a rate of 100-200 ℃ / h and is kept for 0.5-1 h, the temperature is lowered to 400-450 ℃ at a rate of 200-400 ℃ / h, and the muffle furnace is opened for natural cooling to room temperature, so that the chip varistor is obtained.

[0030] By optimizing the pressing parameters and sintering parameters, the microstructure is uniformly formed in a segmented heating manner, the molten zinc oxide is slowly precipitated from the liquid phase in a segmented cooling manner, the defects in the grain and the grain boundary are reduced, and the internal stress is also released to improve the electrical performance of the high disc type varistor, impart higher nonlinearity coefficient, higher energy absorption capacity and lower leakage current to the disc type varistor, and improve the overall use stability and safety reliability of the disc type varistor.

[0031] In summary, the present application has the following advantages:

[0032] 1、The disc type varistor in the present application has the advantages of high nonlinearity coefficient, high energy absorption capacity, high safety reliability, and low leakage current, solving the problem of relatively poor nonlinearity of the zinc oxide varistor produced by the existing solid phase mechanical mixing method.

[0033] 2、The preparation method of the present application is synthesized and prepared by the industrialized solid phase mechanical mixing method, and the preparation method is relatively simple as a whole, the process technology is mature, and industrial production and manufacturing are easy to realize, thereby reducing the production cost of the disc type varistor. DETAILED DESCRIPTION

[0034] In order to further understand the creativity and technical progress of the present application, the preferred embodiments of the present application are discussed in detail below in combination with examples and comparative examples.

[0035] Example: A disc type varistor is made of a zinc oxide varistor ceramic composition prepared by a solid phase mechanical mixing method by sintering. The zinc oxide varistor ceramic composition is composed of 90-98 wt% of main materials and 2-10 wt% of dopants.

[0036] The dopant is at least one of Bi2O3, Sb2O3, Cr2O3, Co2O3, CoO, MnO2, Mn2O3, NiO, CuO, TiO2, Al2O3, SiO2, Fe2O3, and La2O5. Specifically, the zinc oxide varistor ceramic composition is made of raw materials with the following mass percentages: 1-2% Bi2O3, 1-2.5% Sb2O3, 0.5-1% Cr2O3, 0.6-1.2% Co2O3, 0.6-1.2% Mn2O3, 0.5-1% NiO, 0.01-0.10% La2O3, and the balance of main materials.

[0037] The main material is a complex of nano-zinc oxide and single-atom modified zinc oxide or the main material is single-atom modified zinc oxide. Preferably, specifically, the zinc oxide pressure-sensitive ceramic composition is made of 1-2% Bi2O3, 1-2.5% Sb2O3, 0.5-1% Cr2O3, 0.6-1.2% Co2O3, 0.6-1.2% Mn2O3, 0.5-1% NiO, 0.01-0.10% La2O3, and the balance of single-atom modified zinc oxide.

[0038] The content of nano-zinc oxide in the main material can be adjusted to control the high nonlinearity coefficient a of the prepared chip-type pressure-sensitive resistor, different nonlinearity coefficient a values of the chip-type pressure-sensitive resistor can be prepared according to the requirements of the actual application scene, the market competitiveness of the product is improved, the use amount of single-atom modified zinc oxide can be reduced by adding nano-zinc oxide, the total production cost of the product is optimized, the positioning and layout of the chip-type pressure-sensitive resistor products with different nonlinearity coefficient a values are facilitated, and the commercial profit maximization is sought.

[0039] The single-atom modified zinc oxide includes nano-zinc oxide and metal single atoms anchored to defect points on the surface of the nano-zinc oxide. The nano-zinc oxide is n-type zinc oxide with a particle size of ≤500 nm. The nano-zinc oxide can be directly purchased on the market or prepared by existing synthesis methods such as the precipitation method, the sol-gel method, the direct method or the indirect method in the laboratory. In order to commercialize the application, the nano-zinc oxide carrier used in the present application is directly purchased from existing nano-zinc oxide products.

[0040] The metal single atoms are one or a combination of Bi, Sb, Cr, Co, Mn, Ni, Ti, Cu, Al, Fe and La. Preferably, the metal single atoms are Bi, Sb and La, or the metal single atoms are Bi, Sb and La in combination with at least one of Cr, Co, Mn, Ni, Ti, Cu, Al and Fe.

[0041] Further preferably, the metal single atoms are Bi, Sb, Co, Mn and La, and the mass ratio of Bi, Sb, Co, Mn and La in the metal single atoms is 1:1:1:1:(0.1-1). The mass ratio of the nano-zinc oxide to the metal single atoms is (20-100):1, and preferably, the mass ratio of the nano-zinc oxide to the metal single atoms is (40-60):1.

[0042] The preparation method of the single-atom modified zinc oxide includes the following steps:

[0043] Step one, the nano-zinc oxide is placed in a 5-20wt% tartaric acid aqueous solution for ultrasonic dispersion treatment for 1-4h, and then reduced pressure filtration, washing and vacuum drying are performed to obtain the carrier zinc oxide;

[0044] Step two, preparation of metal monatomic precursor: water-soluble metal salt is added to high-purity water, the water-soluble metal salt is any one or a combination of more of chlorides, nitrates, sulfates, acetates, acetylacetone salts, and is subjected to 0.5-1h of ultrasonic dispersion treatment after 0.5-2h of magnetic stirring, and the water-soluble metal salt is fully dissolved to obtain the metal monatomic precursor;

[0045] Step three, under magnetic stirring, the carrier zinc oxide in step one is added to the metal monatomic precursor in step two at a feeding rate of 0.05-0.5g / min, the mass ratio of the carrier zinc oxide to the metal monatomic in the metal monatomic precursor is (20-100):1, and after the feeding of the carrier zinc oxide is completed, the magnetic stirring is continued for 4-24h, followed by 1-4h of ultrasonic dispersion treatment, and the rotary evaporation is performed at 80-100℃ to remove water, and the solid material is obtained after vacuum drying;

[0046] Step four, the solid material is subjected to wet planetary ball milling to obtain superfine powder, the obtained superfine powder is calcined at 400-600℃ for 4-12h, and the planetary ball milling is performed after natural cooling to room temperature to obtain the desired monatomic modified zinc oxide.

[0047] A preparation method of a chip-type piezoresistor, comprising the following steps:

[0048] Step one, preparation of monatomic modified zinc oxide;

[0049] Step two, accurately metered main materials and dopants are mixed according to the proportion to obtain a mixture, the obtained mixture is placed in a planetary ball mill for wet ball milling, the solid-liquid ratio is 1:10-40, a dispersant is pure water or an ethanol aqueous solution, and the wet ball milling is performed under nitrogen protection for 2-8h, and the zinc oxide piezoceramic composition is obtained by filtration, washing, and vacuum drying;

[0050] Step three, 100 parts by weight of the zinc oxide piezoceramic composition is mixed with 6-8 parts by weight of a binder, and the mixture is placed in a disc granulator for granulation treatment, and the piezoceramic granules are obtained by screening through a 50-120 mesh screen;

[0051] Step four, the pressure sensitive ceramic granules in step three are put into a mold to form a sheet-shaped pressing sample by dry pressing at 200±20 MPa / holding for 60-120 s, and the obtained sheet-shaped pressing sample is placed in a muffle furnace for sintering treatment, and the sintering treatment procedure is as follows: the temperature is raised to 550-650 °C at a rate of 200-300 °C / h for 30-45 min for glue removal, then the temperature is raised to 850-900 °C at a rate of 400-600 °C / h, the temperature is raised to 1150-1250 °C at a rate of 1000-1200 °C / h for 2-4 h, the temperature is lowered to 850-900 °C at a rate of 100-200 °C / h for 0.5-1 h, the temperature is lowered to 400-450 °C at a rate of 200-400 °C / h, and the furnace is opened for natural cooling to room temperature, thereby obtaining a sheet-shaped varistor.

[0052] Preparation Example 1: a preparation method of monatomic modified zinc oxide, comprising the following steps:

[0053] Step one, under magnetic stirring at 200 rpm, 10 parts by weight of near-spherical nano zinc oxide CW-ZnO-002 (Shanghai Superwei Nanometer Technology Co., Ltd.) with an average particle size of 200 nm is added to 200 parts by weight of a 20 wt% tartaric acid aqueous solution at a feeding rate of 0.5 g / min, and after the addition of the nano zinc oxide is completed, the magnetic stirring at 200 rpm is maintained for 2 hours, followed by ultrasonic dispersion treatment for 1 h at an ultrasonic frequency of 40 kHz and an ultrasonic frequency of 800 W, and after the ultrasonic dispersion treatment is completed, the wet material obtained by filtration is washed with pure water three times during the vacuum filtration process, and then placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105 °C for 2 h, thereby obtaining carrier zinc oxide;

[0054] Step two, preparation of a metal monatomic precursor: at room temperature, 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, and 2.54 parts by weight of lanthanum chloride heptahydrate are added to 1000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h at an ultrasonic frequency of 40 kHz and an ultrasonic frequency of 800 W, and the water-soluble metal salt is fully dissolved to obtain a metal monatomic precursor;

[0055] Step three, under magnetic stirring, 60 parts by weight of the carrier zinc oxide in step one is added to the metal monatomic precursor in step two at a feeding rate of 0.2 g / min, and the ratio of the total mass of the three metal monatomic bismuth, antimony and lanthanum in the carrier zinc oxide and the metal monatomic precursor is 20:1, and after the feeding of the carrier zinc oxide is completed, the magnetic stirring at 200 rpm is maintained for 20 h, followed by ultrasonic dispersion treatment for 2 h at an ultrasonic frequency of 40 kHz and an ultrasonic frequency of 800 W, and then placed in a 100 °C rotary evaporator for water removal treatment, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105 °C for 2 h, thereby obtaining a solid material;

[0056] Step four, the solid material prepared in step three is put into a planetary ball mill, with zirconium oxide as grinding beads and ethanol aqueous solution (volume ratio of ethanol to water is 2:1) as dispersant, solid-liquid ratio is 1:25, ball milling at 80 rpm for 30 min, then reduced pressure filtration, the wet material obtained by filtration is washed with pure water for three times during the process of reduced pressure filtration, and then vacuum drying treatment is carried out in a vacuum drying oven, vacuum drying temperature is 105℃, vacuum drying time is 2h, to obtain superfine powder, the obtained superfine powder is calcined in a muffle furnace, heating to 450℃ at a rate of 10℃ / min, calcining for 4h, then heating to 600℃ at a rate of 10℃ / min, calcining for 8h, cooling to 200℃ at a rate of 200℃ / h, and then naturally cooling to room temperature, the obtained powder is put into a planetary ball mill for ball milling, with zirconium oxide as grinding beads and ethanol aqueous solution (volume ratio of ethanol to water is 2:1) as dispersant, solid-liquid ratio is 1:25, ball milling at 200 rpm for 15 min, then ball milling at 100 rpm for 30 min, and ball milling at 60 rpm for 30 min, then reduced pressure filtration, the wet material obtained by filtration is washed with pure water for three times during the process of reduced pressure filtration, and then vacuum drying treatment is carried out in a vacuum drying oven, vacuum drying temperature is 105℃, vacuum drying time is 2h, to obtain the required monatomic Bi / Sb / La modified nano zinc oxide.

[0057] Preparation example 2 is different from preparation example 1 in that, in step two of the preparation method of monatomic modified zinc oxide, metal monatomic precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added into 1500 parts by weight of high-purity water, magnetically stirred at 200 rpm for 2h, and then ultrasonic dispersion treatment is carried out for 1h, ultrasonic frequency is 40 kHz, ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal monatomic precursor; in step three, 80 parts by weight of the carrier zinc oxide in step one is added into the metal monatomic precursor in step two under magnetic stirring at a feeding rate of 0.2 g / min, the ratio of the mass of the carrier zinc oxide to the total mass of the four metal monatomic bismuth, antimony, lanthanum and cobalt in the metal monatomic precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring is maintained at 200 rpm for 20h, and then ultrasonic dispersion treatment is carried out for 2h, ultrasonic frequency is 40 kHz, ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying oven for vacuum drying treatment, vacuum drying temperature is 105℃, and vacuum drying time is 2h, to obtain the solid material, and the remaining steps are the same, to obtain monatomic Bi / Sb / La / Co modified nano zinc oxide.

[0058] Preparation Example 3 is different from Preparation Example 1 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, and 3.61 parts by weight of manganese chloride tetrahydrate are added to 1500 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 80 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the metal single atoms of bismuth, antimony, lanthanum, and manganese in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring is maintained at 200 rpm for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105°C for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn modified nano-zinc oxide.

[0059] Preparation Example 4 is different from Preparation Example 1 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, and 3.61 parts by weight of manganese chloride tetrahydrate are added to 1500 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 80 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the metal single atoms of bismuth, antimony, lanthanum, and manganese in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring is maintained at 200 rpm for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105°C for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn modified nano-zinc oxide.

[0060] Preparation Example 5 is different from Preparation Example 1 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.05 parts by weight of nickel chloride hexahydrate are added to 2000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 100 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and nickel in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, and the vacuum drying is performed for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn / Ni modified nano-zinc oxide.

[0061] Preparation Example 6 is different from Preparation Example 1 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 2000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 100 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and nickel in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic power is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, and the vacuum drying is performed for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn / Co modified nano-zinc oxide.

[0062] Preparation Example 7 differs from Preparation Example 1 in that in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 4.05 parts by weight of nickel chloride hexahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 2000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 100 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the metal single atoms of bismuth, antimony, lanthanum, cobalt, and nickel in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, vacuum drying is performed for 2 h, and a solid material is obtained, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Co / Ni modified nano-zinc oxide.

[0063] Preparation Example 8 differs from Preparation Example 1 in that in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, 4.05 parts by weight of nickel chloride hexahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 2500 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 120 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the metal single atoms of bismuth, antimony, lanthanum, manganese, cobalt, and nickel in the metal single-atom precursor is 20:1, after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, and then ultrasonic dispersion treatment is performed for 2 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, vacuum drying is performed for 2 h, and a solid material is obtained, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn / Co / Ni modified nano-zinc oxide.

[0064] Preparation Example 9 is different from Preparation Example 6 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 4000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain a metal single-atom precursor; in step three, under magnetic stirring, 200 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and cobalt in the metal single-atom precursor is 40:1, and after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, followed by 2 h of ultrasonic dispersion treatment, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105°C for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing a single-atom Bi / Sb / La / Mn / Co modified nano-zinc oxide.

[0065] Preparation Example 10 is different from Preparation Example 6 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 6000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain a metal single-atom precursor; in step three, under magnetic stirring, 300 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and cobalt in the metal single-atom precursor is 60:1, and after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, followed by 2 h of ultrasonic dispersion treatment, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105°C for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing a single-atom Bi / Sb / La / Mn / Co modified nano-zinc oxide.

[0066] Preparation Example 11 is different from Preparation Example 6 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 8000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 400 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and cobalt in the metal single-atom precursor is 80:1, and after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, followed by 2 h of ultrasonic dispersion treatment, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, and vacuum drying is performed for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn / Co modified nano-zinc oxide.

[0067] Preparation Example 12 is different from Preparation Example 6 in that, in step two of the preparation method of the single-atom modified zinc oxide, the metal single-atom precursor is prepared: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, and 4.04 parts by weight of cobalt chloride hexahydrate are added to 8000 parts by weight of high-purity water, and after magnetic stirring at 200 rpm for 2 h, ultrasonic dispersion treatment is performed for 1 h, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal single-atom precursor; in step three, under magnetic stirring, 500 parts by weight of the carrier zinc oxide in step one is added to the metal single-atom precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal single atoms of bismuth, antimony, lanthanum, manganese, and cobalt in the metal single-atom precursor is 100:1, and after the feeding of the carrier zinc oxide is completed, magnetic stirring at 200 rpm is maintained for 20 h, followed by 2 h of ultrasonic dispersion treatment, the ultrasonic frequency is 40 kHz, the ultrasonic frequency is 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, the vacuum drying temperature is 105°C, and vacuum drying is performed for 2 h to obtain a solid material, and the remaining steps are the same, thereby preparing single-atom Bi / Sb / La / Mn / Co modified nano-zinc oxide.

[0068] Preparation example 13 is different from preparation example 6 in that: in the preparation method of monatomic modified zinc oxide, step two, the preparation of metal monatomic precursor: 2.32 parts by weight of bismuth nitrate pentahydrate, 3.44 parts by weight of antimony acetylacetone, 2.54 parts by weight of lanthanum chloride heptahydrate, 3.61 parts by weight of manganese chloride tetrahydrate, 4.04 parts by weight of cobalt chloride hexahydrate are added into 15000 parts by weight of high purity water, and after magnetic stirring at 200 rpm for 2 h, 1 h of ultrasonic dispersion treatment is carried out, ultrasonic frequency 40 kHz, ultrasonic frequency 800 W, and the water-soluble metal salt is fully dissolved to obtain the metal monatomic precursor; step three, under magnetic stirring, 750 parts by weight of the carrier zinc oxide in step one is added into the metal monatomic precursor in step two at a feeding rate of 0.2 g / min, the ratio of the total mass of the carrier zinc oxide to the five metal monatomic bismuth, antimony, lanthanum, manganese and cobalt in the metal monatomic precursor is 150:1, after the feeding of the carrier zinc oxide is completed, the magnetic stirring is maintained at 200 rpm for 20 h, and then 2 h of ultrasonic dispersion treatment is carried out, ultrasonic frequency 40 kHz, ultrasonic frequency 800 W, and the obtained powder is placed in a vacuum drying box for vacuum drying treatment, vacuum drying temperature 105℃, vacuum drying for 2 h, to obtain a solid material, and the remaining steps are the same, to prepare the monatomic Bi / Sb / La / Mn / Co modified nano zinc oxide.

[0069] Example 1: A chip type piezoresistor is made of a zinc oxide piezoceramic composition prepared by a solid phase mechanical mixing method. The zinc oxide piezoceramic composition is composed of 93.7wt% of main materials and 6.3wt% of dopants.

[0070] Specifically, the zinc oxide piezoceramic composition is made of raw materials in the following mass percentage: 1.5% of Bi2O3, 2% of Sb2O3, 0.5% of Cr2O3, 0.8% of Co2O3, 0.8% of Mn2O3, 0.65% of NiO, 0.05% of La2O3, 93.7% of the monatomic Bi / Sb / La modified nano zinc oxide in preparation example 1.

[0071] A method for preparing a chip type piezoresistor, comprising the following steps:

[0072] Step one, the preparation of monatomic modified zinc oxide is described in preparation example 1;

[0073] Step two, according to the formula of the zinc oxide varistor ceramic composition, 1.5 parts by weight of Bi2O3, 2 parts by weight of Sb2O3, 0.5 parts by weight of Cr2O3, 0.8 parts by weight of Co2O3, 0.8 parts by weight of Mn2O3, 0.65 parts by weight of NiO, 0.05 parts by weight of La2O3, 93.7 parts by weight of monatomic Bi / Sb / La modified nano-zinc oxide in Preparation Example 1 are put into a small dispersion kettle, mixed and dispersed for 4h under nitrogen protection at 400rpm, and a mixture is obtained by fully mixing and uniformizing. The obtained mixture is placed in a planetary ball mill for wet ball milling, zirconium oxide is used as grinding beads, an ethanol aqueous solution (the volume ratio of ethanol to water is 2:1) is used as a dispersant, the solid-liquid ratio is 1:25, and the ball milling is performed at 320rpm for 30min and at 160rpm for 240min. Then, a reduced-pressure filtration is performed, the wet material obtained by filtration is washed with pure water for three times during the reduced-pressure filtration, and the wet material is placed in a vacuum drying box for vacuum drying treatment at a vacuum drying temperature of 105℃ for 2h, to obtain a zinc oxide varistor ceramic composition.

[0074] Step three, 100 parts by weight of the zinc oxide varistor ceramic composition is mixed with 6.5 parts by weight of a PVA binder, and then placed in a disc granulator for granulation treatment. The granulated material is sieved through a 60-mesh screen, and the sieved material is a varistor ceramic granular material.

[0075] Step four, the varistor ceramic granular material in step three is put into a mold to form a sheet-shaped compression sample by dry pressing at 200MPa / pressure maintaining for 120s. The obtained sheet-shaped compression sample is placed in a muffle furnace for sintering treatment, and the sintering treatment program is as follows: the temperature is raised to 580℃ at a rate of 250℃ / h, the glue is discharged for 45min, then the temperature is raised to 875℃ at a rate of 500℃ / h, the temperature is raised to 1200℃ at a rate of 1000℃ / h and maintained for 4h, the temperature is lowered to 875℃ at a rate of 200℃ / h and maintained for 1h, and the temperature is lowered to 400℃ at a rate of 400℃ / h. The furnace is opened and naturally cooled to room temperature, to obtain a sheet-shaped varistor resistor.

[0076] The difference between Example 2 and Example 1 is that the zinc oxide varistor ceramic composition is made of raw materials with the following mass percentages: 1.5% of Bi2O3, 2% of Sb2O3, 0.5% of Cr2O3, 0.8% of Co2O3, 0.8% of Mn2O3, 0.65% of NiO, 0.05% of La2O3, and 93.7% of monatomic Bi / Sb / La / Co modified nano-zinc oxide in Preparation Example 2.

[0077] Example 3 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn modified nano-zinc oxide in Preparation Example 3.

[0078] Example 4 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Ni modified nano-zinc oxide in Preparation Example 4.

[0079] Example 5 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Ni modified nano-zinc oxide in Preparation Example 5.

[0080] Example 6 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co modified nano-zinc oxide in Preparation Example 6.

[0081] Example 7 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Co / Ni modified nano-zinc oxide in Preparation Example 7.

[0082] Example 8 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co / Ni modified nanometer zinc oxide in Preparation Example 8.

[0083] Example 9 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co modified nanometer zinc oxide in Preparation Example 9.

[0084] Example 10 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co modified nanometer zinc oxide in Preparation Example 10.

[0085] Example 11 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co modified nanometer zinc oxide in Preparation Example 11.

[0086] Example 12 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% of the single atom Bi / Sb / La / Mn / Co modified nanometer zinc oxide in Preparation Example 12.

[0087] Example 13 differs from Example 9 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 20% near-spherical nano-zinc oxide CW-ZnO-002 having an average particle size of 200 nm, 73.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide of Preparation Example 9.

[0088] Example 14 differs from Example 9 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 30% near-spherical nano-zinc oxide CW-ZnO-002 having an average particle size of 200 nm, 63.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide of Preparation Example 9.

[0089] Example 15 differs from Example 9 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 40% near-spherical nano-zinc oxide CW-ZnO-002 having an average particle size of 200 nm, 53.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide of Preparation Example 9.

[0090] Example 16 differs from Example 9 in that the zinc oxide varistor ceramic composition is made from the following mass percentages of raw materials: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 50% near-spherical nano-zinc oxide CW-ZnO-002 having an average particle size of 200 nm, 43.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide of Preparation Example 9.

[0091] Example 17 differs from Example 9 in that the zinc oxide varistor ceramic composition is made from the following raw materials in mass percentage: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 60% near-spherical nano-zinc oxide CW-ZnO-002 with an average particle size of 200 nm, 33.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide in Preparation Example 9.

[0092] Comparative Example 1 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following raw materials in mass percentage: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% near-spherical nano-zinc oxide CW-ZnO-002 with an average particle size of 200 nm.

[0093] Comparative Example 2 differs from Example 1 in that the zinc oxide varistor ceramic composition is made from the following raw materials in mass percentage: 1.5% Bi2O3, 2% Sb2O3, 0.5% Cr2O3, 0.8% Co2O3, 0.8% Mn2O3, 0.65% NiO, 0.05% La2O3, 93.7% mono-atomic Bi / Sb / La / Mn / Co modified nano-zinc oxide in Preparation Example 13.

[0094] Comparative Example 3 differs from Example 1 in that in Step 4, the varistor ceramic granules in Step 3 are put into a mold to form a sheet-shaped compression sample by dry pressing at 200 MPa / pressure maintaining for 120 s, and the obtained sheet-shaped compression sample is placed in a muffle furnace for sintering treatment, and the sintering treatment procedure is as follows: increasing the temperature to 580 ℃ at a rate of 250 ℃ / h for 45 min for degassing, then increasing the temperature to 875 ℃ at a rate of 500 ℃ / h, increasing the temperature to 1200 ℃ at a rate of 1000 ℃ / h for 4 h, decreasing the temperature to 875 ℃ at a rate of 200 ℃ / h for 1 h, decreasing the temperature to 400 ℃ at a rate of 400 ℃ / h, and opening the furnace for natural cooling to room temperature, to obtain a sheet-shaped varistor resistor.

[0095] The sheet-shaped varistor resistors in Examples 1-17 and Comparative Examples 1-3 are measured for the varistor voltage gradient, leakage current and energy absorption capacity according to the test methods specified in GB / T 16528-1996 “Zinc Oxide Varistor Ceramic Materials for Varistor Resistors”, and the non-linear coefficient is measured according to the test method specified in GB / T 10193-1997.

[0096] Table 1: Test parameter table of sheet-shaped varistor resistors in Examples 1-17 and Comparative Examples 1-3

[0097]

[0098] It can be seen from the combination of Examples 1-8 and Comparative Example 1 and Table 1 that the sheet type voltage-dependent resistor prepared by using the single-atom modified nano zinc oxide as the main material in the application has the advantages of high non-linear coefficient, high energy absorption capacity, high safety and reliability, and low leakage current. It can be seen from the combination of Example 6 and Examples 1-5, Examples 7-8 and Table 1 that the single-atom Bi / Sb / La / Mn / Co modified nano zinc oxide synthesized by the metal atoms in the single-atom modified nano zinc oxide in the ratio of Bi / Sb / La / Mn / Co = 1:1:1:1:1 has a potential gradient of the sheet type voltage-dependent resistor of 567.5 V·mm -1 , a high non-linear coefficient α = 87.71, a high energy absorption capacity EA = 300.5 J / cm 3 , a leakage current density J L = 1.05 uA·cm -2 , and has excellent electrical performance.

[0099] It can be seen from the combination of Example 6, Examples 9-12 and Comparative Example 2 and Table 1 that the single-atom Bi / Sb / La / Mn / Co modified nano zinc oxide synthesized by controlling the ratio of the total mass of the metal single atoms of bismuth, antimony, lanthanum, manganese and cobalt in the metal single atom precursor to the carrier zinc oxide to be (20-60):1 has a potential gradient of the sheet type voltage-dependent resistor of ≥540 V·mm -1 , a high non-linear coefficient α≥84, a high energy absorption capacity EA≥290 J / cm 3 , a leakage current density J L ≥1.25 uA·cm -2 , and has relatively excellent electrical performance. Considering the production cost comprehensively, it is appropriate to control the ratio of the total mass of the metal single atoms of bismuth, antimony, lanthanum, manganese and cobalt in the metal single atom precursor to the carrier zinc oxide to be (40-60):1 during the synthesis of the single-atom Bi / Sb / La / Mn / Co modified nano zinc oxide.

[0100] It can be seen from the combination of Example 1 and Comparative Example 3 and Table 1 that the sheet type voltage-dependent resistor prepared by sintering and forming in the application has relatively better electrical performance. The segmented heating mode makes the microstructure uniform, the segmented cooling mode makes the molten zinc oxide slowly precipitate from the liquid phase, reduces the defects in the grain and at the grain boundary, and also releases internal stress to improve the electrical performance of the high sheet type voltage-dependent resistor, gives the sheet type voltage-dependent resistor a higher non-linear coefficient, a higher energy absorption capacity and a lower leakage current, and improves the overall use stability and safety and reliability of the sheet type voltage-dependent resistor.

[0101] In combination with Embodiment 9 and Embodiments 13-17 and in combination with Table 1, it can be seen that as the content of the near-spherical nano-zinc oxide in the zinc oxide varistor ceramic composition increases, the electrical properties of the chip varistor show a downward trend; when the content of the near-spherical nano-zinc oxide is in the range of 20-40wt%, the downward trend of the electrical properties of the chip varistor is relatively slow; and when the content of the near-spherical nano-zinc oxide is >40wt%, the electrical properties of the chip varistor decrease significantly, and thus, from the perspective of the electrical properties of the chip varistor, the content of the near-spherical nano-zinc oxide in the zinc oxide varistor ceramic composition is preferably controlled to be 20-40wt%. In addition, chip varistors have different requirements for their electrical properties according to different actual application scenarios, and by controlling the content of the nano-zinc oxide, the high nonlinearity coefficient, energy absorption capacity and leakage current density of the prepared chip varistor can be adjusted, and the single-atom modified nano-zinc oxide / nano-zinc oxide-based chip varistor with low cost and excellent electrical properties is prepared, which is beneficial to optimizing the total production cost of the product, improving the market competitiveness of the product, facilitating the positioning and layout of chip varistor products with different nonlinearity coefficient α values, and seeking maximum commercial profit.

[0102] In summary, the chip varistor in the present application has the advantages of high nonlinearity coefficient (α≥68), high energy absorption capacity (EA≥235.0J / cm 3 ), high safety and reliability, low leakage current (J L ≤2.0uA•cm -2 ), and solves the problem of poor nonlinearity of zinc oxide varistors produced by the solid-phase mechanical mixing method. The zinc oxide varistor ceramic composition in the present application is synthesized by the industrialized solid-phase mechanical mixing method, and thus the preparation method of the present application is relatively simple and the process technology is mature, facilitating industrialized production and manufacturing, reducing the production cost of the chip varistor, and improving the market competitiveness of the chip varistor product.

[0103] It should be noted that the specific embodiments are only an explanation and description of the technical solutions of the present application, and are not a limitation of the present application. Those skilled in the art can make non-creative modifications to the embodiments according to their needs after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the Patent Law.

Claims

1. A chip varistor, characterized in that: The chip varistor is sintered from a zinc oxide varistor ceramic composition; the zinc oxide varistor ceramic composition consists of a main material and a dopant, the dopant accounting for 2-10 wt% of the total mass of the zinc oxide varistor ceramic composition; the main material is a composite of nano-zinc oxide and single-atom modified zinc oxide, or the main material is single-atom modified zinc oxide; the dopant is composed of Bi2O3, Sb2O3, Cr2O3 combined with at least one of Co2O3, CoO, MnO2, Mn2O3, NiO, CuO, TiO2, Al2O3, SiO2, Fe2O3, and La2O3; The single-atom modified zinc oxide includes nano-zinc oxide and metal single atoms anchored to defect sites on the surface of nano-zinc oxide. The nano-zinc oxide is n-type zinc oxide with a particle size ≤500nm. The metal single atoms are one or more combinations of Bi, Sb, Cr, Co, Mn, Ni, Ti, Cu, Al, Fe, and La. The mass ratio of nano-zinc oxide to metal single atoms is (20-100):

1.

2. A chip varistor according to claim 1, characterized in that: The mass ratio of the nano-zinc oxide to the metal single atom is (40-60):

1.

3. A chip varistor according to claim 2, characterized in that: The metal single atom is Bi, Sb, or La, or the metal single atom is Bi, Sb, or La combined with at least one of Cr, Co, Mn, Ni, Ti, Cu, Al, or Fe.

4. A chip varistor according to claim 3, characterized in that: The metal single atoms are Bi, Sb, Co, Mn, and La, and the mass ratio of Bi, Sb, Co, Mn, and La in the metal single atoms is 1:1:1:1: (0.1~1).

5. A chip varistor according to claim 1, characterized in that: The method for preparing the single-atom modified zinc oxide includes the following steps: Step 1: Place the nano zinc oxide in a 5-20 wt% tartaric acid aqueous solution and ultrasonically disperse for 1-4 hours. Then filter under reduced pressure, wash, and vacuum dry to obtain carrier zinc oxide. Step 2, preparation of metal single-atom precursor: Add water-soluble metal salt to high-purity water, stir magnetically for 0.5-2 hours, and then perform ultrasonic dispersion treatment for 0.5-1 hours to fully dissolve the water-soluble metal salt and obtain the metal single-atom precursor; Step 3: Under magnetic stirring, the carrier zinc oxide from Step 1 is added to the metal single-atom precursor from Step 2 at a feeding rate of 0.05-0.5 g / min. The mass ratio of the carrier zinc oxide to the metal single-atom precursor is (20-100):

1. After the carrier zinc oxide is added, magnetic stirring is continued for 4-24 hours, followed by ultrasonic dispersion treatment for 1-4 hours. The water is removed by rotary evaporation at 80-100℃, and the solid material is obtained after vacuum drying. Step 4: The solid material is wet-milled into ultrafine powder. The obtained ultrafine powder is calcined at 400-600℃ for 4-12 hours and then naturally cooled to room temperature before being refined by planetary ball milling to obtain the desired single-atom modified zinc oxide.

6. A chip varistor according to claim 5, characterized in that: The water-soluble metal salt is any one or a combination of chloride, nitrate, sulfate, acetate, and acetylacetone salts.

7. A chip varistor according to claim 1, characterized in that: The zinc oxide varistor ceramic composition is made from the following raw materials in the indicated mass percentages: 1-2% Bi₂O₃, 1-2.5% Sb₂O₃, 0.5-1% Cr₂O₃, 0.6-1.2% Co₂O₃, 0.6-1.2% Mn₂O₃, 0.5-1% NiO, 0.01-0.10% La₂O₃, with the balance being single-atom modified zinc oxide.

8. A method for preparing a chip varistor according to any one of claims 1-7, characterized in that: The steps are as follows: Step 1: Preparation of single-atom modified zinc oxide; Step 2: Mix the accurately measured main material and dopant evenly according to the formula to obtain a mixture. Place the mixture in a planetary ball mill for wet ball milling with a solid-liquid ratio of 1:10-40. The dispersant is pure water or an aqueous ethanol solution. Wet ball mill for 2-8 hours under nitrogen protection. Filter, wash, and vacuum dry to obtain the zinc oxide varistor ceramic composition. Step 3: Mix 100 parts by weight of zinc oxide pressure-sensitive ceramic composition with 6-8 parts by weight of binder and place the mixture in a disc granulator for granulation. The mixture is then sieved through a 50-120 mesh screen to obtain pressure-sensitive ceramic granules. Step four: The varistor ceramic granules from step three are put into a mold and dry-pressed to obtain a sheet-shaped pressed sample. The obtained sheet-shaped pressed sample is placed in a muffle furnace for sintering treatment, and cooled to room temperature to obtain a sheet varistor.

9. The preparation method according to claim 8, characterized in that: In step four, the varistor ceramic granules from step three are placed into a mold and dry-pressed at 200±20MPa for 60-120s to obtain a sheet-shaped pressed sample. The obtained sheet-shaped pressed sample is then placed in a muffle furnace for sintering. The sintering procedure is as follows: the temperature is increased to 550-650℃ at 200-300℃ / h and the binder is removed for 30-45 minutes. Then, the temperature is increased to 850-900℃ at 400-600℃ / h, increased to 1150-1250℃ at 1000-1200℃ / h and held for 2-4 hours. The temperature is then decreased to 850-900℃ at 100-200℃ / h and held for 0.5-1 hour. Finally, the temperature is decreased to 400-450℃ at 200-400℃ / h and allowed to cool naturally to room temperature after the furnace is opened to obtain the sheet-type varistor.

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