CN102136315B - Multilayer-ceramic total-area LNO (lanthanum nickel oxide)/Ag/LNO composite electrode and preparation method thereof - Google Patents

Abstract

Multilayer ceramic full-area LNO/Ag/LNO composite electrode, including at least two overlapping ceramic sheets, between two adjacent ceramic sheets is "LNO conductive buffer layer/Ag electrode layer/LNO conductive buffer layer", located on the top The surface of the ceramic sheet at the bottom is covered with the LNO conductive buffer layer and the Ag electrode layer in turn. The shape and area of the end face of the LNO conductive buffer layer are the same as those of the ceramic sheet, and the shape and area of the end face of the Ag electrode layer are the same as those of the end face of the LNO conductive buffer layer. The shapes and areas are the same, and the ceramic sheet and the LNO conductive buffer layer, and between the LNO conductive buffer layer and the Ag electrode layer are sintered to form an integrated structure. The process steps of the above composite electrode preparation method are: (1) surface treatment of ceramic sheets, (2) preparation of LNO precursor solution, (3) preparation of the first unit body, (4) preparation of the second unit body , (5) Combination and sintering of the unit body.

Description

Multilayer Ceramic Full Area LNO/Ag/LNO Composite Electrode and Preparation Method

technical field

The invention belongs to the field of composite electrode materials, in particular to a multilayer ceramic full-area LNO/Ag/LNO composite electrode and a preparation method thereof.

Background technique

The electrodes of various ceramic components in electrical engineering are usually made of metals such as Ag, Pt or Au, which are firmly attached to an end surface of the ceramic material for conduction through sputtering, infiltration, spraying and other processes. Directly use metal as the electrode layer, which has good conductivity and certain ductility. However, metal electrodes have two significant disadvantages: (1) the crystal constant does not match the ceramic substrate, resulting in the accumulation of interface defects, which easily causes the electrode to delaminate and delaminate, resulting in device failure; (2) under high-frequency electric field, the metal electrode and ceramic It is easy to diffuse between the phases, and chemical reactions occur, which deteriorates the dielectric properties.

The emergence of conductive oxides such as La _0.5 Sr _0.5 CoO ₃ , YB ₂ Cu ₃ O _7-δ , and SrRuO ₃ provides a new way to solve the defects of metal electrodes. Among many conductive oxides, LaNiO ₃ (abbreviated as "LNO", in this patent application, LNO is used to represent LaNiO ₃ ) has a lattice constant of 0.384nm, and lead zirconate titanate (abbreviated as "PZT", In this patent application, PZT is used to represent lead zirconate titanate), lanthanum-doped lead zirconate titanate (abbreviated as "PLZT", in this patent application, PLZT is used to represent lanthanum-doped lead zirconate titanate) and other piezoelectric ceramic lattice constants are very close, and thus have received widespread attention. So far, people have used pulsed laser deposition (PLD), radio frequency magnetron sputtering (RF), chemical solution deposition (CSD) and other methods to prepare LNO with resistivity on the order of 10 ^-3 Ω·cm. Thin film electrodes, but compared with good conductors of noble metals such as Ag, their resistivity is still relatively high.

Combining the advantages of conductive oxides and metal electrodes, Chen Mingsen and Wu Taibor et al. prepared LNO/Pt composite electrodes (see: Appl Phys Lett, 1996, 68: 1430-1432). Although this composite electrode overcomes the defects of interdiffusion between ceramics and electrodes and high resistivity when only conductive oxides are used as electrodes when only metals are used as electrodes, Pt is a more expensive metal than Ag, making electrodes In addition, the sintering temperature of the LNO/Pt composite electrode prepared by this method is relatively high (about 1000 ° C), and the LNO film is easy to decompose at this sintering temperature, and it is easy to promote the formation of PbO in piezoelectric ceramics PZT and PLZT. Volatilization, resulting in a decline in the electrical performance of composite electrodes and devices, and environmental pollution; moreover, due to the high sintering temperature of this method, the preparation process consumes more energy. In addition to the above-mentioned problems, the LNO/Pt electrode disclosed in the paper published by Chen Mingsen et al. is a partial electrode (that is, the area of the electrode is smaller than the area of the working surface of the base). Different strains are generated, which leads to the accumulation of stress at the edge of the electrode, resulting in a decrease in the conductivity of the electrode of the component.

CN101538156A discloses a preparation method of a buffer layer induced texture ferroelectric thin film, the method is to drop LaNiO ₃ sol on SiO ₂ /Si or Pt/LNO/SiO ₂ /Si substrate, and form LaNiO ₃ buffer by suspension coating method layer, and then drop ferroelectric oxide sol on the LaNiO ₃ buffer layer to form a ferroelectric thin film layer by suspension coating. The product prepared by this method cannot be used directly as an electrode, but is only an intermediate material, and its use depends on subsequent processing.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to provide a multilayer ceramic full-area LNO/Ag/LNO composite electrode and its preparation method, so that the electrode material can not only have excellent conductivity, but also greatly increase the service life .

The multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention includes at least two overlapping ceramic sheets, and between adjacent two ceramic sheets is "LNO conductive buffer layer/Ag electrode layer/LNO conductive buffer layer ”, the surface of the ceramic sheet at the top and bottom covers the LNO conductive buffer layer and the Ag electrode layer sequentially. The shape and area of the end face of the LNO conductive buffer layer are the same as those of the ceramic sheet, and the shape and area of the end face of the Ag electrode layer are the same as those of the LNO The shape and area of the end faces of the conductive buffer layer are the same, and the spaces between the ceramic sheet and the LNO conductive buffer layer, and between the LNO conductive buffer layer and the Ag electrode layer are sintered to form an integrated structure.

In the multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention, the thickness of the LNO conductive buffer layer is preferably 200 nm to 300 nm.

In the multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention, the thickness of the Ag electrode layer is controlled at 20 microns to 100 microns.

For the multilayer ceramic full-area LNO/Ag/LNO composite electrode described in the present invention, the ceramic sheet is preferably made of PLZT or PZT.

The preparation method of the multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention, the process steps are as follows:

(1) Surface treatment of ceramic sheets

Firstly, the ceramic sheet is polished, then manually cleaned and ultrasonically cleaned in sequence;

(2) Preparation of LNO precursor solution

The LNO precursor solution was prepared with nickel acetate and lanthanum nitrate as solute, deionized water and glacial acetic acid as solvent, and polyvinyl alcohol as chelating agent. The molar ratio of nickel acetate and lanthanum nitrate was 1:1, and deionized water and ice The volume ratio of acetic acid is 1:3~5; put nickel acetate into the reaction vessel and add glacial acetic acid, stir at normal pressure and room temperature until the nickel acetate is completely dissolved, then add lanthanum nitrate and heat up to 60°C~70°C while stirring Add deionized water at ℃, when the lanthanum nitrate is completely dissolved, heat up to 70℃~80℃ under stirring and add polyvinyl alcohol, the amount of polyvinyl alcohol added is a solution formed by nickel acetate, lanthanum nitrate, deionized water, and glacial acetic acid As a benchmark, add 10g to 45g of polyvinyl alcohol per liter of the solution; when the polyvinyl alcohol is completely dissolved, adjust the concentration of the solution by evaporating the solvent or adding a solvent so that the content of LNO in the solution is 0.1mol /L～0.3mol/L, after filtering to remove impurities, the LNO precursor solution is obtained;

(3) Preparation of the first unit body

The first type of unit body consists of a ceramic sheet, an LNO conductive buffer layer covered on both ends of the ceramic sheet and an Ag electrode layer covered on an LNO conductive buffer layer;

①Apply the LNO precursor solution prepared in step (2) on the both ends of the ceramic sheet treated in step (1) to form a LNO wet film by using the rotary glue-spinning method, and conduct heat treatment to form an LNO conductive buffer layer. The heat treatment adopts The method of layer-by-layer treatment, that is, heat treatment is carried out for each layer of LNO wet film, and the heat treatment operation of each layer of LNO wet film is the same. After the last heat treatment is completed, keep it warm at 600°C to 850°C for 20min to 60min, and then cool to room temperature with the furnace;

②Print the silver paste on a LNO conductive buffer layer using a 300-350-mesh screen screen, and dry the wet sheet obtained by printing at 80°C-100°C for 5min-15min each time, and print The number of times and the number of times of drying the wet sheet is limited to the thickness of the Ag electrode layer reaching 20 microns to 100 microns;

(4) Preparation of the second unit body

The second unit body consists of a ceramic sheet, LNO conductive buffer layers respectively covered on both ends of the ceramic sheet, and Ag electrode layers respectively covered on the two LNO conductive buffer layers;

①Apply the LNO precursor solution prepared in step (2) on both ends of the ceramic sheet treated in step (1) by the spin-coating method to form an LNO wet film and conduct heat treatment to form a conductive LNO film. For the buffer layer, the heat treatment adopts a layer-by-layer treatment method, that is, heat treatment is carried out for each layer of LNO wet film, and the heat treatment operation of each layer of LNO wet film is the same. The limit is 300 nanometers. When the last heat treatment is completed, keep it at 600°C-850°C for 20min-60min, and then cool to room temperature with the furnace;

②Print the silver paste on the two LNO conductive buffer layers with a 300-350-mesh screen in full area, and dry the wet film obtained by this printing at 80°C-100°C for 5min-15min, and print The number of times and the number of times of drying the wet sheet is limited to the thickness of the Ag electrode layer reaching 20 microns to 100 microns;

(5) Combination and sintering of unit body

Taking a second unit body as a backsheet, stacking one or more first unit bodies on the second unit body to form a green body of a multilayer ceramic full-area LNO/Ag/LNO composite electrode, and then Put the green body into a sintering furnace with a pressure device, raise the temperature to 750°C-850°C and sinter for 20-60 minutes under the condition of applying a pressure of 1MPa-3MPa to the axial direction of the green body, and then cool to room temperature with the furnace, and then obtain more Layer ceramic full area LNO/Ag/LNO composite electrode.

In the preparation steps of the first unit body and the second unit body of the method of the present invention, the heat treatment operation of the LNO wet film is preferably: drying at 150°C to 200°C for 10min to 20min, and decomposing organic matter at 300°C to 400°C 10min～20min, pre-crystallization treatment at 500℃～600℃ for 1min～5min.

In the method of the present invention, the silver paste slurry can be purchased directly from the market, and can also be prepared according to the following formula and operation: the mass parts of the silver powder are 100 parts, the mass parts of the solvent are 4 parts to 6 parts, and the mass parts of the adhesive The mass parts are 10 to 60 parts, and the silver powder, solvent and adhesive measured according to the above mass parts are ground, and the grinding time is such that the fineness of the silver paste is ≤6 μm and the viscosity at 25 °C reaches 8×10 ⁴ mPa·s～12×10 ⁴ mPa·s is limited; the solvent is bismuth oxide, and the adhesive is composed of terpineol, turpentine, nitrocellulose, cyclohexanone and dibutyl phthalate, and the pine The mass parts of oleyl alcohol are 3.8 parts to 4.5 parts, the mass parts of turpentine oil are 1.7 parts to 2.6 parts, the mass parts of nitrocellulose are 1.3 parts to 1.6 parts, the mass parts of cyclohexanone are 14.3 parts to 16.2 parts, and the ortho-benzene The mass parts of dibutyl diformate are 3.1-4.2 parts.

In the method of the present invention, the ceramic sheet is preferably made of PLZT or PZT.

The present invention has the following beneficial effects:

1. The multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention has excellent fatigue resistance and breakdown electric field strength, and its technical indicators are as follows:

(1) Electrode resistivity <1mΩ·cm;

(2) Working voltage -300～+300V;

(3) Frequency > 10 ⁴ Hz, number of continuous pulse reversals > 10 ⁸ (no damage).

2. The multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention solves the problem of uneven stress distribution caused by the "staggered inner electrode" structure, thereby overcoming the phenomenon of ceramic and electrode fracture caused by tensile stress, extending the service life of the device.

3, the method of the present invention, make Ag electrode layer and LNO conductive buffer layer, the bonding surface of LNO conductive buffer layer and ceramic plate form the solid solution similar in structure, thereby Ag electrode layer and LNO conductive buffer layer, LNO conductive buffer layer and pottery The sheets are tightly combined and extremely difficult to crack and peel off.

4. The method of the present invention carries out a heat treatment every time a layer of LNO wet film is applied, and the last process of the heat treatment operation is a pre-crystallization treatment at 500°C to 600°C for 1 to 5 minutes. Under this process condition, on the one hand, it can Continue to remove the residual organic substances, and more importantly, make the current film structure in an amorphous state, which is conducive to the tight adhesion between the multi-layer coated films; when the overall thickness is reached, keep it at 600℃～850℃ for 20min～ 60 minutes can make the multi-layer film co-crystallize, so the grain distribution of the LNO conductive buffer layer is uniform, eliminating the interlayer grain boundary, promoting the uniform distribution of the electric field, reducing the resistance of the carrier movement, and improving the conductivity of the oxide film. Thus improving the overall performance of the composite electrode.

5. The equipment used in the method of the present invention is conventional equipment, and the pressure device for sintering can be a mechanical pressure device or other pressure devices, and the requirements for the sintering atmosphere are low, so the cost is low and it is easy for industrial production.

Description of drawings

Fig. 1 is a kind of structural representation of multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is the structural representation of first kind of unit body;

Fig. 4 is the top view of Fig. 3;

Fig. 5 is the structural representation of the second unit body;

Figure 6 is a top view of Figure 5;

Fig. 7 is the scanning electron micrograph of the Ag electrode layer after adopting external force to peel off the ceramic sheet with the multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention, wherein, (a), (b), (c), ( d) Ag electrode layer scanning electron micrographs of composite electrodes obtained by applying 0MPa, 1MPa, 2MPa, and 3MPa pressures to the green body in the axial direction, respectively;

Fig. 8 is a relationship diagram between the mechanical pressure applied axially to the green body during sintering and the resistivity of the obtained multilayer ceramic full-area LNO/Ag/LNO composite electrode;

Figure 9 is a fatigue performance test diagram of the multilayer ceramic full-area LNO/Ag/LNO composite electrode obtained by applying different mechanical pressures to the green body axially during sintering;

Fig. 10 is the hysteresis loop diagram of multilayer ceramic capacitor, wherein (a) is the hysteresis of the capacitor (applying 2MPa mechanical pressure sintering) prepared with 4 layers of ceramic full-area LNO/Ag/LNO composite electrode of the present invention The loop, (b) is the hysteresis loop of the capacitor prepared with silver electrodes.

In the figure, 1-ceramic sheet, 2-LNO conductive buffer layer, 3-Ag electrode layer.

Detailed ways

The multilayer ceramic full-area LNO/Ag/LNO composite electrode of the present invention and its preparation method will be further described below in conjunction with the accompanying drawings.

Example 1

This embodiment prepares the four-layer ceramic full-area LNO/Ag/LNO composite electrode shown in Figure 1 and Figure 2, and the process steps are as follows:

(1) Surface treatment of ceramic sheets

The ceramic sheet is a 0.5mm PLZT sheet, and its surface treatment is surface polishing and cleaning in sequence; the surface polishing adopts a precision grinding and polishing machine, the ceramic sheet is fixed on the polishing machine by paraffin, and the front and back sides are polished according to the following operations: use 1500 ^# emery paper, polished at 45rpm for 2 hours, then replaced with polishing fabric, polished at 45rpm for 16 hours; cleaning includes manual cleaning and ultrasonic cleaning, first remove the paraffin on the surface of the ceramic sheet by manual cleaning, and then use ultrasonic cleaning: ① Put the ceramic sheet into a container filled with acetone, put the container into an ultrasonic cleaner to re-vibrate and clean for 5 minutes, then take out the ceramic sheet, and wash it with deionized water for 3 times; ②Put the ceramic sheet after cleaning with deionized water into Put it into a container filled with absolute ethanol, ultrasonically clean it for 5 minutes, then take out the ceramic sheet, and wash it with deionized water for 3 times; , and then take out the ceramic sheet and put it in a drying oven to dry at 60°C for 15 minutes;

(2) Preparation of LNO precursor solution

Use nickel acetate and hydrated lanthanum nitrate as solutes, deionized water and glacial acetic acid as solvents, and polyvinyl alcohol as a chelating agent to prepare LNO precursor solution. The molar ratio of nickel acetate and hydrated lanthanum nitrate is 1:1, deionized water The volume ratio to glacial acetic acid is 1:3; put nickel acetate into the reaction vessel and add glacial acetic acid, stir at normal pressure and room temperature (25°C) until the nickel acetate is completely dissolved, then add hydrated lanthanum nitrate and heat up while stirring Add deionized water to 60°C, when the hydrated lanthanum nitrate is completely dissolved, heat up to 70°C under stirring and add polyvinyl alcohol, the amount of polyvinyl alcohol is formed by nickel acetate, hydrated lanthanum nitrate, deionized water, and glacial acetic acid Solution as a benchmark, add polyvinyl alcohol 30g per liter of the solution; when the polyvinyl alcohol is completely dissolved, adjust the concentration of the solution by evaporating the solvent or adding a solvent, so that the content of LNO in the solution is 0.2mol/ L, and then filter out impurities through a 0.2 micron filter to obtain a green and transparent LNO precursor solution; the above raw materials are all analytically pure.

(3) Preparation of the first unit body

The shape and structure of the first type of unit body are shown in Figure 3 and Figure 4. It consists of a ceramic sheet 1, an LNO conductive buffer layer 2 covered on both ends of the ceramic sheet and an Ag electrode layer covered on an LNO conductive buffer layer. 3 composition;

①Apply the LNO precursor solution prepared in step (2) on both ends of the ceramic sheet treated in step (1) to form a LNO wet film by using the rotary glue-spinning method, and then conduct heat treatment to form an LNO conductive buffer layer, uniform glue The speed is 3500rpm, the mixing time is 20s, and the heat treatment adopts the method of layer-by-layer treatment, that is, heat treatment is carried out for each layer of LNO wet film, and the heat treatment operation of each layer of LNO wet film is the same, all of which are: sequentially drying at 180°C for 15 minutes, Decompose organic matter at 350°C for 10 minutes, and pretreat at 550°C for 2 minutes; the number of times of rotating glue and heat treatment is limited when the thickness of the LNO film reaches 300 nm. After the last heat treatment is completed, keep it at 750°C for 30 minutes, and then cool it down room temperature;

2. silver paste slurry is prepared by silver powder, solvent and bonding agent, the mass parts of silver powder are 100 parts, the mass parts of solvent are 5 parts, the mass parts of bonding agent are 30 parts, described solvent is bismuth oxide, described The adhesive is composed of terpineol, turpentine, nitrocellulose, cyclohexanone and dibutyl phthalate, the mass parts of terpineol are 4.0, the mass parts of turpentine are 2.0 parts, and the mass parts of nitrocellulose are 1.5 parts part, the mass part of cyclohexanone is 15.0 parts, and the mass part of dibutyl phthalate is 3.5 parts; The silver powder, solvent and binding agent measured by the above mass parts are ground to the size of the slurry with a three-roll mill Fineness ≤ 6μm, viscosity at 25°C is 10×10 ⁴ mPa·s; the prepared silver paste is printed on a LNO conductive buffer layer with a 350-mesh screen in full area. The wet sheet obtained by the first printing was dried at 80°C for 10 minutes. The number of printing and drying times of the wet sheet was limited to the thickness of the Ag electrode layer reaching 80 microns; the excess Ag/LNO material overflowing around the ceramic sheet was treated by grinding and polishing; The above raw materials are analytically pure.

(4) Preparation of the second unit body

The shape and structure of the second type of unit body are shown in Figure 5 and Figure 6, consisting of a ceramic sheet 1, an LNO conductive buffer layer 2 covering both ends of the ceramic sheet and Ag electrodes respectively covering the two LNO conductive buffer layers Layer 3 composition;

1. The method of covering the LNO conductive buffer layer 2 on the two ends of the ceramic sheet 1 is the same as the above-mentioned step (3) to prepare the first unit body;

② The silver powder, solvent and adhesive used in the preparation of the silver paste and its operation are the same as the preparation of the first unit in the above step (3); the prepared silver paste is printed on two LNOs with a 350-mesh screen. On the conductive buffer layer, dry the wet sheet obtained by printing for 10 minutes at 80°C for each printing. The excess Ag/LNO material is processed by grinding and polishing;

(5) Combination and sintering of unit body

Using a second type of unit body shown in Figure 5 and Figure 6 as a negative, three first type of unit bodies shown in Figure 3 and Figure 4 are stacked on the second type of unit body to form a four-layer ceramic full-body A blank of an area LNO/Ag/LNO composite electrode; a blank of combining twelve said four-layer ceramic full-area LNO/Ag/LNO composite electrodes.

Put twelve green bodies into a sintering furnace with a mechanical pressure device (the mechanical pressure device is the mechanical pressure device disclosed in ZL200810044344.7 patent), every three green bodies are a group, and four groups of green bodies Apply 0Mpa, 1Mpa, 2Mpa, 3MPa mechanical pressure respectively in the axial direction, then raise the temperature to 850°C at 3.5°C/min under the pressure, keep it at this temperature for 20min, and then cool it to room temperature with the furnace to obtain twelve four Layer ceramic full area LNO/Ag/LNO composite electrode.

The Ag electrode layer 3 of the four-layer ceramic full-area LNO/Ag/LNO composite electrode with axial pressures of 0Mpa, 1Mpa, 2Mpa, and 3Mpa during sintering was scanned with a scanning electron microscope, and the obtained images are shown in Figure 7. 7 It can be seen that under different pressure sintering conditions, the greater the pressure, the tighter the interface between the composite electrode and the ceramic contact, and the interface structure under 3MPa pressure is the best.

The four-layer ceramic full-area LNO/Ag/LNO composite electrodes with axial pressures of 0Mpa, 1Mpa, 2Mpa, and 3Mpa during sintering were tested by the four-probe method. Their resistivities are shown in Figure 8. From Figure 8 It can be seen that as the sintering pressure increases, the resistivity of the composite electrode decreases.

Three four-layer ceramic full-area LNO/Ag/LNO composite electrodes sintered with axial pressure of 0Mpa, 2Mpa, and 3Mpa were tested for remnant polarization. The change of logarithm logN is shown in Figure 9, and it can be seen from Figure 9 that the greater the sintering pressure, the greater the normalized remanent polarization Pr, and the better the fatigue resistance of piezoelectric ceramics prepared by using the composite electrode material of the present invention. good.

The four-layer ceramic full-area LNO/Ag/LNO composite electrode that axially presses 3Mpa during sintering is used to prepare a capacitor, and its hysteresis loop is shown in (a) curve in Fig. (b) curve (the hysteresis loop of the capacitor that silver electrode Ag/PLZT/Ag is prepared) compares, can find out: adopt the four-layer ceramic capacitor hysteresis loop shape that composite electrode material of the present invention prepares is more Well, the polarization is better than ceramic capacitors with silver electrodes.

The above test uses a four-probe instrument: K2400 voltage/current source meter (Keithley, USA), polarization parameter tester: Precision LC (Radient, USA), pulse generator: Precision High Voltage Interface±4000V (Radient, USA) , and a high-voltage amplifier: Model 609E-6 (Terk, USA). The test working voltage is -300～+300V, the electric field reversal frequency is 1.8×104Hz, and the electrodes are not damaged after continuous testing for 6 hours.

Example 2

In this example, a three-layer ceramic full-area LNO/Ag/LNO composite electrode is prepared, and the process steps are as follows:

(1) Surface treatment of ceramic sheets

The surface treatment of the 1 mm PZT sheet of the ceramic sheet is surface polishing and cleaning in sequence; the operations of surface polishing and cleaning are the same as in Example 1.

(2) Preparation of LNO precursor solution

The LNO precursor solution was prepared with nickel acetate and lanthanum nitrate as solute, deionized water and glacial acetic acid as solvent, and polyvinyl alcohol as chelating agent. The molar ratio of nickel acetate and lanthanum nitrate was 1:1, and deionized water and ice The volume ratio of acetic acid is 1:5; put nickel acetate into the reaction vessel and add glacial acetic acid, stir at normal pressure and room temperature (29°C) until the nickel acetate is completely dissolved, then add lanthanum nitrate and heat up to 70°C while stirring Add deionized water, and when the lanthanum nitrate is completely dissolved, heat up to 80°C under stirring and add polyvinyl alcohol. The amount of polyvinyl alcohol is based on the solution formed by nickel acetate, lanthanum nitrate, deionized water, and glacial acetic acid. Add polyvinyl alcohol 10g to liter described solution; After polyvinyl alcohol dissolves completely, adjust the concentration of described solution by the mode of evaporating solvent or adding solvent, make the content of LNO in the described solution be 0.1mol/L, then through The 0.2 micron filter removes impurities, and a green and transparent LNO precursor solution is obtained; the above raw materials are all analytically pure.

(3) Preparation of the first unit body

The shape and structure of the first type of unit body are shown in Figure 3 and Figure 4. It consists of a ceramic sheet 1, an LNO conductive buffer layer 2 covered on both ends of the ceramic sheet and an Ag electrode layer covered on an LNO conductive buffer layer. 3 composition;

①Apply the LNO precursor solution prepared in step (2) on both ends of the ceramic sheet treated in step (1) to form a LNO wet film by using the rotary glue-spinning method, and then conduct heat treatment to form an LNO conductive buffer layer, uniform glue The speed is 3500rpm, the mixing time is 20s, and the heat treatment adopts the method of layer-by-layer treatment, that is, heat treatment is carried out for each layer of LNO wet film, and the heat treatment operation of each layer of LNO wet film is the same: drying at 150°C for 20 minutes, Decompose organic matter at 300°C for 20 minutes, and pretreat at 500°C for 5 minutes; the number of times of spin-spinning and heat treatment is limited when the thickness of the LNO film reaches 200 nm. After the last heat treatment is completed, keep it at 600°C for 60 minutes, and then cool it down room temperature;

2. silver paste slurry is prepared by silver powder, solvent and bonding agent, the mass parts of silver powder are 100 parts, the mass parts of solvent are 5 parts, the mass parts of bonding agent are 60 parts, described solvent is bismuth oxide, described The adhesive is composed of terpineol, turpentine, nitrocellulose, cyclohexanone and dibutyl phthalate, the mass parts of terpineol are 4.5 parts, the mass parts of turpentine are 2.6 parts, and the mass parts of nitrocellulose are 1.3 parts part, the mass part of cyclohexanone is 16.0 parts, and the mass part of dibutyl phthalate is 4.2 parts; The silver powder, solvent and binding agent measured by the above mass parts are ground to the size of the slurry with a three-roll mill Fineness ≤ 6μm, viscosity at 25°C is 12×10 ⁴ mPa·s; the above raw materials are all analytically pure.

Print the prepared silver paste on a LNO conductive buffer layer with a 300-mesh screen, and dry the wet sheet obtained by printing for 5 minutes at 100°C for each printing. The number of times of printing and the wet sheet The number of times of drying is limited when the thickness of the Ag electrode layer reaches 50 microns; the excess Ag/LNO material overflowing around the ceramic sheet is treated by grinding and polishing;

(4) Preparation of the second unit body

The shape and structure of the second type of unit body are shown in Figure 5 and Figure 6, consisting of a ceramic sheet 1, an LNO conductive buffer layer 2 covering both ends of the ceramic sheet and Ag electrodes respectively covering the two LNO conductive buffer layers Layer 3 composition;

1. The method of covering the LNO conductive buffer layer 2 on the two ends of the ceramic sheet 1 is the same as the above-mentioned step (3) to prepare the first unit body;

② The silver powder, solvent and adhesive used in the preparation of the silver paste and its operation are the same as the preparation of the first unit in the above step (3); the prepared silver paste is printed on two LNOs with a 300-mesh screen. On the conductive buffer layer, dry the wet sheet obtained by printing for 15 minutes at 100°C for each printing. The excess Ag/LNO material is processed by grinding and polishing;

(5) Combination and sintering of unit body

With a second type of unit body shown in Figure 5 and Figure 6 as a negative, two first type of unit bodies shown in Figure 3 and Figure 4 are stacked on the second type of unit body to form a three-layer ceramic full body. A green body of an area LNO/Ag/LNO composite electrode; a green body of combining six of the three-layer ceramic full-area LNO/Ag/LNO composite electrodes.

Put six green bodies into a sintering furnace with a mechanical pressure device (the mechanical pressure device is the same as in Example 1), every three green bodies are a group, and apply 1Mpa, 2Mpa, 3MPa mechanical pressure, then heated to 750°C for sintering for 60min under pressure, and then cooled to room temperature with the furnace, and six three-layer ceramic full-area LNO/Ag/LNO composite electrodes were obtained.

The performance test of the three-layer ceramic full-area LNO/Ag/LNO composite electrode prepared in this example is carried out with the same test equipment as in Example 1, the working voltage is -300~+300V, and the inversion test frequency is 1.5×10 ⁴ Hz , There is no damage to the electrode after continuous testing for 6 hours. The resistivity test results are as follows:

Sintering pressure 1Mpa 2Mpa 3MPa Electrode resistivity 0.67mΩ·cm 0.56mΩ·cm 0.48mΩ·cm

Claims (5)

1. a kind of multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ preparation method of composite electrode, it is characterized in that process steps are as follows: (1) Surface treatment of ceramic sheets Firstly, the ceramic sheet is polished, then manually cleaned and ultrasonically cleaned in sequence; (2) Preparation of _LaNiO3 precursor solution Using nickel acetate and lanthanum nitrate as solute, deionized water and glacial acetic acid as solvent, polyvinyl alcohol as chelating agent to prepare LaNiO ₃ precursor solution, the molar ratio of nickel acetate and lanthanum nitrate is 1:1, deionized water and The volume ratio of glacial acetic acid is 1:3~5; put nickel acetate into the reaction vessel and add glacial acetic acid, stir at normal pressure and room temperature until the nickel acetate is completely dissolved, then add lanthanum nitrate and heat up to 60°C~ Add deionized water at 70°C, when the lanthanum nitrate is completely dissolved, heat up to 70°C~80°C under stirring and add polyvinyl alcohol, the amount of polyvinyl alcohol to be added is based on nickel acetate, lanthanum nitrate, deionized water, and glacial acetic acid Solution is _a benchmark, every liter of said solution adds polyvinyl alcohol 10g～45g; 0.1mol/L～0.3mol/L, and then filter to remove impurities, and then obtain the LaNiO ₃ precursor solution; (3) Preparation of the first unit body The first type of unit body consists of a ceramic sheet, a _LaNiO3 conductive buffer layer covered on both ends of the ceramic sheet and an Ag electrode layer covered on a _LaNiO3 conductive buffer layer; ①Apply the _LaNiO3 precursor solution prepared in step (2) on the both ends of the ceramic sheet after step (1) to form a _LaNiO3 wet film and perform heat treatment to form a _LaNiO3 conductive buffer layer , the heat treatment adopts the method of layer-by-layer treatment, that is, heat treatment is carried out for each layer of LaNiO ₃ wet film, and the heat treatment _{operation of each layer of LaNiO 3 wet} film is the same. ~300 nanometers, when the last heat treatment is completed, keep it at 600°C~850°C for 20min~60min, and then cool to room temperature with the furnace; ② Print the silver paste on a LaNiO ₃ conductive buffer layer using a 300-350-mesh screen screen, and dry the wet sheet obtained by printing at 80°C-100°C for 5min-15min each time. The number of times of printing and the number of times of drying the wet sheet is limited to the thickness of the Ag electrode layer reaching 20 microns to 100 microns; (4) Preparation of the second unit body The second type of unit body consists of a ceramic sheet, a _LaNiO3 conductive buffer layer respectively covered on both ends of the ceramic sheet, and an Ag electrode layer respectively covered on the two _LaNiO3 conductive buffer layers; ①Apply the _LaNiO3 precursor solution prepared in step (2) on the both ends of the ceramic sheet after step (1) to form a _LaNiO3 wet film and perform heat treatment to form a _LaNiO3 conductive buffer layer , the heat treatment adopts the method of layer-by-layer treatment, that is, heat treatment is carried out for each layer of LaNiO ₃ wet film, and the heat treatment _{operation of each layer of LaNiO 3 wet} film is the same. ~300 nanometers, when the last heat treatment is completed, keep it at 600°C~850°C for 20min~60min, and then cool to room temperature with the furnace; ②Print the silver paste on the two LaNiO ₃ conductive buffer layers using a 300-350-mesh screen in full area, and dry the wet sheet obtained by printing at 80°C-100°C for 5min-15min each time. The number of times of printing and the number of times of drying the wet sheet is limited to the thickness of the Ag electrode layer reaching 20 microns to 100 microns; (5) Combination and sintering of unit body Taking a second unit body as a negative, stacking one or more first unit bodies on the second unit body to form a multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ composite electrode green body, and then Put the green body into a sintering furnace with a pressure device, raise the temperature to 750°C-850°C and sinter for 20min-60min under the condition of applying a pressure of 1MPa-3MPa to the axial direction of the greenbody, and then cool to room temperature with the furnace, that is A multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ composite electrode was obtained. 2. The preparation method of the multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ composite electrode according to claim 1, characterized in that the heat treatment operation of the LaNiO ₃ wet film is: sequentially drying at 150°C-200°C for 10min-20min , Decompose organic matter at 300°C to 400°C for 10min to 20min, and pre-crystallize at 500°C to 600°C for 1min to 5min. 3. according to claim 1 and 2 described multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ preparation method of composite electrode, it is characterized in that silver paste slurry is formulated by silver powder, solvent and binding agent, the quality of silver powder Parts are 100 parts, the mass parts of the solvent are 4 parts to 6 parts, the mass parts of the adhesive are 10 parts to 60 parts, the silver powder, solvent and adhesive measured by the above mass parts are ground, and the grinding time is as follows: The fineness of the silver paste is ≤6μm, and the viscosity at 25°C is limited to 8×10 ⁴ mPa·s～12×10 ⁴ mPa·s; the solvent is bismuth oxide, and the adhesive is made of terpineol , turpentine, nitrocellulose, cyclohexanone and dibutyl phthalate, the mass parts of terpineol are 3.8-4.5 parts, the mass parts of turpentine are 1.7-2.6 parts, and the mass parts of nitrocellulose are 1.3 parts parts to 1.6 parts, the parts by mass of cyclohexanone are 14.3 parts to 16.2 parts, and the parts by mass of dibutyl phthalate are 3.1 parts to 4.2 parts. 4. The method for preparing a multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ composite electrode according to claim 1 or 2, wherein the ceramic sheet is made of lanthanum-doped lead zirconate titanate or lead zirconate titanate. 5. The preparation method of the multilayer ceramic full-area LaNiO ₃ /Ag/LaNiO ₃ composite electrode according to claim 3, wherein the ceramic sheet is made of lanthanum-doped lead zirconate titanate or lead zirconate titanate.

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