CN108329015B - Doped modified nickel oxide-based NTC (negative temperature coefficient) thermistor material and preparation method thereof - Google Patents

Abstract

The invention relates to a semiconductor ceramic material, in particular to a semiconductor ceramic material which is suitable for preparing a thermistor material with negative temperature coefficient of resistance (NTC). The NTC thermistor material provided by the invention is mainly composed of nickel oxide, the room temperature resistivity of the thermistor element can be adjusted by adjusting the content of trace semiconductive doping element fluorine, and the room temperature resistivity and the constant value of the NTC material can be further adjusted by adding trace modified element aluminum. The NTC thermistor material is suitable for sintering and molding of thermosensitive ceramic elements, thin-film thermosensitive elements and low-temperature co-fired laminated thermosensitive elements. The thermistor material has the characteristics of good stability, good consistency and good repeatability, has the characteristics of controllable electrical characteristics such as resistance value, material constant, resistance temperature coefficient and the like, and is suitable for the fields of temperature measurement, temperature control and line compensation, protection of circuits and electronic elements, and instruments and application of flow velocity, flow and ray measurement.

Description

Doped modified nickel oxide-based NTC (negative temperature coefficient) thermistor material and preparation method thereof

Technical Field

The present invention relates to a Negative Temperature Coefficient (NTC) thermistor material for manufacturing a thermistor element having an NTC effect. The temperature control device is suitable for the fields of temperature measurement, temperature control, line compensation, protection of circuits and electronic elements, flow velocity, flow and ray measurement instruments and application.

Background

The thermistor is a device made by using the property of material resistivity varying with temperature, and includes a Positive Temperature Coefficient (PTC) thermistor in which the resistivity increases with increasing temperature or a Negative Temperature Coefficient (NTC) thermistor element in which the resistivity decreases with increasing temperature. NTC thermistor elements and devices have been widely used in temperature measurement, control, temperature compensation, surge current suppression, protection of circuits and electronic elements, and related instruments and applications for flow rate, flow and ray measurement. NTC thermistors and NTC temperature sensors have a large market demand and are widely used in the fields of communications, medical treatment, computers, automobiles, electronics, home appliances, and the like. With the rapid development of the global and domestic electronic information industry, the great demand and development of the NTC thermistor and the NTC temperature sensor are further driven.

In the normal temperature NTC thermistor, transition metals of manganese and nickel are mainly adoptedAnd NTC thermistor elements of spinel structure made of oxides of cobalt, iron and copper, which have been widely researched and applied. For example, the NTC thermistor material disclosed in chinese patent CN1332405C is synthesized by a liquid-phase coprecipitation method using nitrates of manganese, nickel, magnesium, and aluminum as raw materials; the Co-Mn-Fe-O NTC thermal sensitive ceramic material is prepared by taking cobalt nitrate, manganese nitrate and ferric sulfate as raw materials and is disclosed in Chinese invention patent CN 100395849C; CoO-Co published in Chinese invention patent CN1006667B₂O₃-Fe₂O₃A ceramic-based NTC thermosensitive material; us patent 6861622 discloses a manganese-nickel-cobalt-iron-copper series NTC heat sensitive material as described in the patent. The common feature of these NTC thermistor materials is that they contain oxides of at least two transition metals and are composed of a spinel-type cubic crystal structure as a main crystal phase.

In the NTC thermistor material with spinel structure made of transition metal oxides of manganese, nickel, cobalt, iron and copper, because the volatilization temperature of the transition metal oxides is low, the volatilization of raw material components is easy to generate in the preparation and sintering process of the NTC thermistor element, so that the final components of the product, the consistency of the product and the repeatability of different production batches are difficult to control. The NTC ceramic with the spinel structure has large room temperature resistivity, and the resistance value is not easy to regulate and control; reducing the resistivity of the material often results in a reduction in the temperature coefficient, which affects the NTC properties of the thermistor. Meanwhile, in the manganese-nickel-cobalt compound with a spinel structure, cations in the tetrahedron and octahedron of the manganese-nickel-cobalt compound are slowly redistributed along with time within the temperature range of 200-400 ℃ to cause structure relaxation. The relaxation phenomenon causes the instability of the electrical property of the NTC ceramic material, easily causes the aging of the material, and influences the property and the service life of the material.

In recent years, in order to develop a novel oxide-based NTC thermistor material, scientists have also developed some new material systems, such as hexagonal BaTiO₃The system (Chinese patent ZL 200910043274.8; Chinese patent ZL 200910303525.1) and rutile type SnO₂Ceramics (electronic components and Materials, 2009(6): 56-59; Journal of Materials Science-Materials in EleFirst, LaCoO was found in ctronics, 2014,25(12):5552-₃The perovskite-based Ceramic has excellent NTC characteristics (Journal of the European Ceramic Society,2000,20(14-15):2367-₃、BaBiO₃、SrTiO₃、YMnO₃And LaMnO₃NTC thermal sensitive ceramics (Journal of the American Ceramic Society,1997,80(8): 2153-. With the increasing requirement of industries such as air conditioners, refrigerators, microwave devices, automobiles and the like on the stability of NTC thermistors, it is very important to improve the existing component system or develop a novel component system.

In view of the above situation, the present invention adopts a material modified by doping trace elements with nickel oxide as a main component to obtain a thermistor material system with a good NTC effect, and the room temperature resistivity of the thermistor element and the temperature constant of the material can be adjusted by changing the trace elements.

Disclosure of Invention

It is an object of the present invention to provide an NTC thermistor material system capable of producing NTC thermistor materials having a negative temperature coefficient of resistance effect. The thermistor material can adjust the room temperature resistivity of the thermistor element and the temperature constant of the material by changing the trace doping element.

The NTC thermistor material comprises the following components: ni_1-xAl_xO_1-yF_yWherein x is 0.0001 to 0.1; y is 0.0001 to 0.1.

The key component of the NTC material of the invention is Ni_1-xAl_xO_1-yF_yThe components of the formula contain nickel, aluminum, oxygen and fluorine elements, the raw materials Ni and Al for preparing the thermistor can be simple substances, oxides, inorganic salts or organic salts containing the elements, and the raw material of the element F can be acid containing F and fluorineCompound, organic matter containing F. The semiconductive element fluorine is used for adjusting the room temperature resistivity of the thermistor element, the element aluminum is used for adjusting the room temperature resistivity of the thermistor element and a material constant and a temperature coefficient which show the thermosensitive property, and meanwhile, the sintering property of the thermistor can be enhanced due to the introduction of the aluminum.

The preparation method of the embodiment of the invention can obtain the phase composition of high-purity single phase, and the prepared NTC thermistor element has stable and high performance and reliability.

The main key point of the invention is the ingredient formula of the thermistor material, and the synthesis method and the production process can be correspondingly adjusted according to requirements in the practical application process, so that the invention has high flexibility. For example, the raw material may be selected from compounds containing simple substances, oxides, inorganic salts, or organic salts of these elements; the synthesis method can be realized by adopting a solid-state reaction method, a sol-gel method, a coprecipitation method, a vapor deposition method or other synthesis methods of ceramic materials.

The invention relates to a method for detecting the characteristics of a thermistor material, which adopts coated silver paste as an electrode to measure the room temperature resistance and the resistance-temperature characteristic of an element. Other electrode materials such as aluminum electrodes, In-Ga alloy electrodes or nickel electrode materials can be selected for practical production.

The NTC thermistor material has the following characteristics and advantages: the material has simple components, rich raw materials and environmental protection; the sintering temperature is low in the preparation process, and the preparation method is suitable for production of NTC thermistor elements such as ceramic elements and films; using anion fluorine as a semiconductive doping element; fourthly, the room temperature resistance value of the thermistor element can be adjusted in a large range by adjusting the content of the semiconductive doping element fluorine; the material constant and temperature coefficient of the thermosensitive element can be adjusted in a large range by adjusting the content of aluminum in the composition.

The electrical property of the NTC thermistor material can meet the following parameter requirements: resistivity at room temperature ρ₂₅＝1Ω·cm^-1～1MΩ·cm^-1The material constant B is 1000-6000K.

The invention is further illustrated by the following examples. The following embodiments are merely examples consistent with the technical contents of the present invention, and do not illustrate that the present invention is limited to the contents described in the following examples. The invention is characterized by the ingredient formula, the raw materials, the process method and the steps can be correspondingly adjusted according to the actual production conditions, and the flexibility is high.

Drawings

FIG. 1 is a resistance-temperature characteristic curve of different aluminum contents in the NTC thermal sensitive ceramic resistance material in the embodiment. The figure illustrates that all materials exhibit typical NTC properties and that the trace introduction of aluminium can significantly alter the resistivity of the material and the NTC material constant.

FIG. 2 is a graph of the room temperature resistivity of the NTC thermal sensitive ceramic resistance material and the variation of the material constant with the aluminum content in the embodiment. The trace introduction of Al can obviously change the resistivity of the material and the NTC material constant.

FIG. 3 is a thermistor material (Ni) prepared in example 6_0.97Al_0.03O_0.95F_0.05) Resistance-temperature dependence of repeated measurements from room temperature to 300 ℃. The material has good temperature cycle stability.

FIG. 4 shows the room temperature resistivity with fluorine content (Ni) in the NTC thermistor material of the present invention_0.98Al_0.01O_1-yF_y) A curve of variation. The figure shows that the room temperature resistivity of the NTC thermistor material can be effectively adjusted by introducing the fluorine in a trace amount.

Detailed Description

Example 1

This example shows the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0 and y is 0.04. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. The material preparation was carried out according to the following experimental process steps:

(1) the initial raw material is mixed with NiO_0.96F_0.04Proportioning and weighing NiCO₃·2Ni(OH)₂·4H₂O 62.7050g、NH₄F 0.7408g；

(2) Respectively dissolving the raw materials weighed in the previous step: NiCo₃·2Ni(OH)₂·4H₂Dissolving O in dilute nitric acid, and then dropwise adding ammonia water to adjust the pH value to about 8; NH (NH)₄Dissolving F in distilled water;

(3) mixing the two solutions prepared in the previous step together, stirring and uniformly mixing by using a magnetic stirring heater, and heating and drying;

(4) calcining the powder prepared in the last step at 850 ℃, and keeping the temperature for 5 hours;

(5) mixing the powder prepared in the last step with 5-8 ml of polyvinyl alcohol aqueous solution per 100 g of the powder, granulating and pressing into a blank; the blank body is in a disc shape, the diameter of the disc is 15 mm, and the thickness of the disc is 3.5-4.0 mm;

(6) sintering the blank obtained in the last step, wherein the sintering temperature is 1300 ℃, the heat preservation is carried out for 1 hour, and the heating and cooling rates are both 5 ℃ per minute, so as to obtain the NTC heat-sensitive ceramic chip;

(7) grinding two surfaces of the NTC thermal sensitive ceramic chip prepared in the last step, coating silver paste, and curing at 600 ℃ to prepare an electrode;

(8) and (4) carrying out resistance-temperature characteristic measurement on the NTC thermistor element prepared in the last step.

The properties of the prepared material are shown in table 1, fig. 1 and fig. 2.

Example 2

This example shows the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0.003 and y is 0.04. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. Aluminium isopropoxide C₉H₂₁AlO₃. The material preparation was carried out according to the following experimental process steps:

(1) mixing the initial raw material with Ni_0.997Al_0.003O_0.96F_0.04Preparing materials according to a formula, and weighing NiCO₃·2Ni(OH)₂·4H₂O 62.5169g、NH₄F 0.7408g、C₉H₂₁AlO₃ 0.3064g；

(2) Respectively dissolving the raw materials weighed in the previous step, wherein NiCO is₃·2Ni(OH)₂·4H₂Dissolving O in dilute nitric acid, adding ammonia water to regulate pH value to about 8, and adding NH₄F in distilled water, C₉H₂₁AlO₃Dissolving in ethanol;

(3) the preparation process was the same as in steps (3) to (8) of example 1

The properties of the prepared material are shown in table 1, fig. 1 and fig. 2.

Example 3

This example is represented by the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0.005 and y is 0.04. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. Aluminium isopropoxide C₉H₂₁AlO₃. . The material preparation was carried out according to the following experimental process steps:

(1) mixing the initial raw material with Ni_0.995Al_0.005O_0.96F_0.04Preparing materials according to a formula, and weighing NiCO₃·2Ni(OH)₂·4H₂O 62.3915g、NH₄F 0.7408g、C₉H₂₁AlO₃ 0.5106g；

(2) The preparation process is the same as the steps (2) to (3) in example 2.

The properties of the prepared material are shown in table 1, fig. 1 and fig. 2.

Example 4

This example is represented by the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0.01, and y is 0.04. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. Aluminium isopropoxide C₉H₂₁AlO₃. . The material preparation was carried out according to the following experimental process steps:

(1) mixing the initial raw material with Ni_0.99Al_0.01O_0.96F_0.04Preparing materials according to a formula, and weighing NiCO₃·2Ni(OH)₂·4H₂O 62.0780g、NH₄F 0.7408g、C₉H₂₁AlO₃ 1.0213g；

(2) The preparation process is the same as the steps (2) to (3) in example 2.

The properties of the prepared material are shown in table 1, fig. 1 and fig. 2.

Example 5

This example is represented by the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0.02, and y is 0.04. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. Aluminium isopropoxide C₉H₂₁AlO₃. . The material preparation was carried out according to the following experimental process steps:

(1) mixing the initial raw material with Ni_0.98Al_0.02O_0.96F_0.04Preparing materials according to a formula, and weighing NiCO₃·2Ni(OH)₂·4H₂O 61.4509g、NH₄F 0.7408g、C₉H₂₁AlO₃ 2.0425g；

(2) The preparation process is the same as the steps (2) to (3) in example 2.

The properties of the prepared material are shown in table 1, fig. 1 and fig. 2.

Example 6

This example is represented by the formula Ni_1-xAl_xO_1-yF_yAnd (3) preparing materials, wherein x is 0.03 and y is 0.05. The starting material is selected from basic nickel carbonate NiCo₃·2Ni(OH)₂·4H₂O, ammonium fluoride NH₄F. Aluminum isopropoxide C9H21AlO 3. . The material preparation was carried out according to the following experimental process steps:

(1) mixing the initial raw material with Ni_0.97Al_0.03O_0.95F_0.05Preparing materials according to a formula, and weighing NiCO₃·2Ni(OH)₂·4H₂O 60.8239g、NH₄F 0.926g、C₉H₂₁AlO₃ 3.0638g；

(2) The preparation process is the same as the steps (2) to (3) in example 2.

The properties of the prepared materials are shown in table 1, fig. 2 and fig. 3.

TABLE 1 index of Material Properties of examples

Claims (3)

1. A negative temp coefficient thermistor material is composed of Ni _x1-Al _x O_1-yF _y Whereinx= 0.0001~0.1，y = 0.0001~0.1。

2. The negative temperature coefficient thermistor material of claim 1, wherein the element Ni of the thermistor is prepared from the raw materials including simple substances, oxides, inorganic salts, organic salts; the raw material of the element Al for preparing the thermistor can be simple substances, oxides, inorganic salts and organic salts containing the elements; the raw material of element F for preparing the thermistor can be F-containing acid, fluoride and F-containing organic matter.

3. The negative temperature coefficient thermistor material according to claim 1, which is prepared by the following process:

(1) with basic nickel carbonate NiCO₃•2Ni(OH)₂•4H₂O, ammonium fluoride NH₄F. Aluminium isopropoxide C₉H₂₁AlO₃As raw material, the raw material is mixed with Ni _x1-Al _x O_1-yF _y Preparing materials according to a formula, and weighing NiCO with corresponding weight₃•2Ni(OH)₂•4H₂O、NH₄F、C₉H₂₁AlO₃；

(2) Respectively dissolving the raw materials weighed in the previous step, wherein NiCO is₃•2Ni(OH)₂•4H₂Dissolving O in dilute nitric acid, and adding ammonia water to regulate pH value to 8, NH₄F in distilled water, C₉H₂₁AlO₃Dissolving in ethanol;

(3) mixing the three solutions prepared in the previous step together, stirring and uniformly mixing by using a magnetic stirring heater, and heating and drying;

(4) calcining the powder prepared in the last step at 850 ℃, and keeping the temperature for 5 hours;

(5) mixing the powder prepared in the last step with 5-8 ml of polyvinyl alcohol aqueous solution per 100 g of the powder, granulating and pressing into a blank; the blank body is in a disc shape, the diameter of the disc is 15 mm, and the thickness of the disc is 3.5-4.0 mm;

(6) sintering the blank obtained in the last step, wherein the sintering temperature is 1300 ℃, the heat preservation is carried out for 1 hour, and the heating and cooling rates are both 5 ℃ per minute, so as to obtain the NTC heat-sensitive ceramic chip;

and (3) grinding two surfaces of the NTC thermosensitive ceramic chip prepared in the last step, coating silver paste, and curing at 600 ℃ to prepare an electrode, thereby obtaining the NTC thermosensitive resistance element.

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