CN101792320A - Method for sintering high-dielectric CaCu3Ti4O12 ceramics by using spark plasma - Google Patents

Method for sintering high-dielectric CaCu3Ti4O12 ceramics by using spark plasma Download PDF

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Publication number
CN101792320A
CN101792320A CN 201010125384 CN201010125384A CN101792320A CN 101792320 A CN101792320 A CN 101792320A CN 201010125384 CN201010125384 CN 201010125384 CN 201010125384 A CN201010125384 A CN 201010125384A CN 101792320 A CN101792320 A CN 101792320A
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China
Prior art keywords
sintering
cacu
dielectric
mould
pottery
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CN 201010125384
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杨芝
张悦
王文波
熊锐
石兢
阮学锋
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Wuhan University WHU
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Wuhan University WHU
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Abstract

The invention provides a method for sintering (SPS) high-dielectric ceramics CaCu3Ti4O12(CCTO for shot) by using spark plasma. The method comprises the following steps of: putting pure CCTO powder in a mould, and putting the mould between upper and lower electrodes in an SPS sintering cavity; closing the sintering cavity, vacuum-pumping the sintering cavity, and performing heating, pressurization and heat preservation of the mould; cooling the mould along with a furnace, reducing the pressure, and closing a vacuum pump; and after the temperature is reduced to a certain extent, taking the product out of the sintering cavity. An XRD result of the sintering product shows that the sample is of pure phase, the compact appearance can be observed by using an SEM, and the measurement on the dielectric property shows that the sample has a higher relative dielectric constant and lower loss at room temperature.

Description

Utilize discharge plasma sintering high-dielectric CaCu 3Ti 4O 12The method of pottery
Technical field:
The present invention relates to a kind of high dielectric CaCu 3Ti 4O 12The sintering method of pottery.
Background introduction:
CaCu 3Ti 4O 12(CCTO) be the relatively more popular high dielectric electronic material of a kind of present research, the relative permittivity of its room temperature low-frequency range is up to 10 4~10 5, and dielectric properties (100-300K) in wide temperature range are more stable, and therefore, the CCTO material has application promise in clinical practice aspect microelectronics.
The conventional sintering method of CCTO pottery be with common tabletting machine under certain pressure (generally up to tens even hundreds of megapascal (MPa)) with CCTO powder compression back high temperature sintering in retort furnace in flakes.In order to obtain comparatively fine and close pottery, need through long sintering time (generally wanting tens hours).Therefore, energy consumption is bigger.
Discharge plasma sintering (SPS) is a kind of sintering method that can obtain finer and close flaky material by the short period of time sintering, and it is widely used in various alloys of preparation and stupalith.But because the property of CCTO, the SPS sintering does not also use in the production of CCTO pottery at present.
Summary of the invention:
Purpose of the present invention is exactly that property according to CCTO provides a kind of method that can utilize SPS sintering CCTO pottery, and the method that can have now relatively significantly reduces the high temperature sintering time effectively to cut down the consumption of energy, and can possess or increase the high dielectric property of CCTO again.
Technical scheme of the present invention is made up of following steps:
1. with pure CaCu 3Ti 4O 12Pack into mould and this mould put between upper/lower electrode in the discharge plasma sintering chamber of powder;
2. close the sintering chamber, open vacuum pump, the sintering chamber is vacuumized;
3. to the pressurization that heats up of sintering chamber, add pressure when waiting to be warming up to 800-980 degree centigrade, be incubated 5-60 minute, furnace cooling and then, pass vacuum pump with the temperature decompression to the 20-70 MPa;
4. when equitemperature drops to below 100 ℃, product is taken out in the sintering chamber.
Above-mentioned pure CaCu 3Ti 4O 12Powder can make with sol-gel method.
In above-mentioned intensification pressure process, the pressure size should raise and progressively increasing with temperature, should only add a little pressure when low temperature.And in above-mentioned furnace cooling process, pressure can be reduced to minimum.
If above-mentioned mould is a graphite jig, then utilize the surface of technique scheme gained pottery certain thickness cementation zone can occur, for the carbon of removing infiltration need carry out 500-900 ℃ again with the sample that sinters in retort furnace, the anneal of insulation more than 2 hours, the part that the back gained ceramic surface of then will annealing again decomposes owing to carburizing polishes off and polishes.
The agglomerating CCTO pottery according to the present invention, the XRD of its agglomerating product show sample as a result are pure phase, and it is dense to use SEM can observe its pattern, and dielectric properties are measured show sample and at room temperature had higher relative permittivity and lower loss.
Description of drawings:
Accompanying drawing 1 is the profile scanning Electronic Speculum shape appearance figure of agglomerating CCTO of the present invention;
Accompanying drawing 2 is the dielectric properties of the CCTO of the different sintering temperatures of the present invention.Wherein Fig. 2-1 is the relative permittivity comparison diagram, and Fig. 2-2 is the loss comparison diagram;
Accompanying drawing 3 is the dielectric properties of the CCTO of different sintered heat insulating times of the present invention.Wherein Fig. 3-1 is the relative permittivity comparison diagram, and Fig. 3-2 is the loss comparison diagram;
Accompanying drawing 4 is the dielectric properties of the CCTO of the different sintering pressures of the present invention.Wherein Fig. 4-1 is the relative permittivity comparison diagram, and Fig. 4-2 is the loss comparison diagram;
Accompanying drawing 5 is the dielectric properties of the CCTO of different annealing temperature of the present invention.Wherein Fig. 5-1 is the relative permittivity comparison diagram, and Fig. 5-2 is the loss comparison diagram;
Accompanying drawing 6 is the dielectric properties of the CCTO of 2 hours and 10 hours for the present invention's soaking time of annealing.Wherein Fig. 6-1 is the relative permittivity comparison diagram, and Fig. 6-2 is the loss comparison diagram;
Accompanying drawing 7 is the dielectric properties of discharge plasma sintering and ordinary sinter.Wherein Fig. 7-1 is the relative permittivity comparison diagram, and Fig. 7-2 is the loss comparison diagram;
In the above-mentioned accompanying drawing: the F-frequency; ε '-relative permittivity; Tan δ-loss.
Embodiment
Be example with the graphite jig below, in conjunction with the accompanying drawings the present invention be further introduced:
Embodiment one:
Preparation condition is: the sintered heat insulating time is 5 minutes, and sintering temperature is 980 degrees centigrade, and sintering pressure is 51 MPas, and annealing temperature is 600 degrees centigrade, and the annealing soaking time is 2 hours.
From accompanying drawing 1 as can be known, behind the short period of time sintering, resulting sample is very fine and close.
Embodiment two;
Preparation condition is: the sintered heat insulating time is 5 minutes, and sintering pressure is 51 MPas, and annealing temperature is 600 degrees centigrade, annealing soaking time be 10 hours, but sintering temperature be one be 800 degrees centigrade another be 980 degrees centigrade.
From accompanying drawing 2-1 and accompanying drawing 2-2 as can be known: the relative permittivity of corresponding pottery under 10000Hz the former be: 3.0 * 10 3, the latter is 7.0 * 10 3, the loss under this frequency the former be: 0.12, and the latter is: 0.12;
Embodiment three:
Preparation condition is: sintering temperature is 980 degrees centigrade, and sintering pressure is 51 MPas, and annealing temperature is 600 degrees centigrade, and the annealing soaking time is 10 hours, but one of sintered heat insulating time be 5 minutes another be 60 minutes.
From accompanying drawing 3-1 and accompanying drawing 3-2 as can be known: the relative permittivity of corresponding pottery under 10000Hz the former be: 7.0 * 10 3, the latter is 2.0 * 10 4, the loss under this frequency the former be: 0.10, and the latter is: 0.18;
Embodiment four:
Preparation condition is: sintering temperature is 980 degrees centigrade, and the sintered heat insulating time is 5 minutes, and annealing temperature is 600 degrees centigrade, and the annealing soaking time is 10 hours, but one of sintering pressure is 20 MPas; Another is 70 MPas.
From accompanying drawing 4-1 and accompanying drawing 4-2 as can be known: the relative permittivity of corresponding pottery under 10000Hz the former be: 8.0 * 10 3, the latter is 8.0 * 10 3, the loss under this frequency the former be: 0.09, and the latter is: 0.09;
Embodiment five:
Preparation condition is: sintering temperature is 980 degrees centigrade, and the sintered heat insulating time is 5 minutes, and sintering pressure is 51 MPas, annealing soaking time be 10 hours, but one of annealing temperature be 500 degrees centigrade another be 900 degrees centigrade.
From accompanying drawing 5-1 and accompanying drawing 5-2 as can be known: the relative permittivity of corresponding pottery under 10000Hz the former be: 7.0 * 10 2, the latter is 7.0 * 10 4, the loss under this frequency the former be: 0.50, and the latter is: 0.27;
Embodiment six:
Preparation condition is: sintering temperature is 980 degrees centigrade, and the sintered heat insulating time is 5 minutes, and sintering pressure is 51 MPas, and annealing temperature is 600 degrees centigrade, and the annealing soaking time is 2 hours and 10 hours.
From accompanying drawing 6-1 and accompanying drawing 6-2 as can be known: corresponding pottery the former relative permittivity under 10000Hz is: 7 * 10 2, the latter is 2 * 10 4, the former loss is under this frequency: 0.07, and the latter is 0.16.
Embodiment seven:
The preparation condition of discharge plasma sintering is: sintering temperature is 980 ℃, the sintered heat insulating time is 5 minutes, and sintering pressure is 51 MPas, and annealing temperature is 600 ℃, the annealing soaking time is: 2 hours, the ordinary sinter preparation condition was: sintering temperature is 1035 ℃ of insulations 3 hours.The current consumption of preceding a kind of sintering processing is about: 12Kw.h, the current consumption of a kind of sintering processing in back is about: 58Kw.h.
From accompanying drawing 7-1 and accompanying drawing 7-2 as can be known: the relative permittivity of corresponding pottery under 10000Hz the former be: 7.0 * 10 3, the latter is 7.0 * 10 2Loss under this frequency the former be: 0.07 latter is: therefore 0.04. compares with the sample of ordinary sinter gained with the sample that discharge plasma sintering comes out, loss ratio is more approaching, but relative permittivity is bigger 10 times than the sample that ordinary sinter comes out, and current consumption is 1/5th of ordinary sinter current consumption.

Claims (5)

1. utilize discharge plasma sintering high-dielectric CaCu 3Ti 4O 12The method of pottery, it is characterized in that: described method is made up of following step:
1) with pure CaCu 3Ti 4O 12Pack into mould and this mould put between upper/lower electrode in the discharge plasma sintering chamber of powder;
2) close the sintering chamber, open vacuum pump, the sintering chamber is vacuumized;
3) to the pressurization that heats up of sintering chamber, add pressure when waiting to be warming up to 800-980 degree centigrade, be incubated 5-60 minute, furnace cooling and then, pass vacuum pump with the temperature decompression to the 20-70 MPa;
When 4) equitemperature drops to below 100 ℃, product is taken out in the sintering chamber.
2. the discharge plasma sintering high-dielectric CaCu that utilizes as claimed in claim 1 3Ti 4O 12The method of pottery is characterized in that: described pure CaCu 3Ti 4O 12Powder utilizes sol-gel method to make.
3. the discharge plasma sintering high-dielectric CaCu that utilizes as claimed in claim 1 or 2 3Ti 4O 12The method of pottery is characterized in that: in described intensification pressure process, the pressure size should raise and progressively increasing with temperature, should only add a little pressure when low temperature; In above-mentioned furnace cooling process, then pressure should be reduced to minimum.
4. the discharge plasma sintering high-dielectric CaCu that utilizes as claimed in claim 1 or 2 3Ti 4O 12The method of pottery, it is characterized in that: when described mould is graphite jig, the product that sinters is carried out 500-900 ℃ again in retort furnace, the anneal of insulation more than 2 hours, the part that decompose owing to carburizing on the products obtained therefrom surface, back of then will annealing again polishes off and polishes.
5. the discharge plasma sintering high-dielectric CaCu that utilizes as claimed in claim 3 3Ti 4O 12The method of pottery, it is characterized in that: when described mould is graphite jig, the product that sinters is carried out 500-900 ℃ again in retort furnace, insulation anneal more than 2 hours, the part that decompose owing to carburizing on the products obtained therefrom surface, back of then will annealing again polishes off and polishes.
CN 201010125384 2010-03-11 2010-03-11 Method for sintering high-dielectric CaCu3Ti4O12 ceramics by using spark plasma Pending CN101792320A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105568383A (en) * 2016-01-06 2016-05-11 中国科学院上海光学精密机械研究所 Synthesis method of raw material for CaCuTi4O12 crystal growth and preparation method of CaCuTi4O12 crystal
CN109912305A (en) * 2019-04-25 2019-06-21 重庆大学 A kind of high-potential gracient, low-dielectric loss CaCu3Ti4O12Voltage-sensitive ceramic and preparation method thereof
CN112521166A (en) * 2020-12-14 2021-03-19 江西科技学院 Low dielectric loss CaCu3Ti4O12Negative pressure sintering method of ceramic
CN113773055A (en) * 2021-10-15 2021-12-10 中国船舶重工集团公司第七二五研究所 Preparation method of metal oxide coating electrode

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
《JOURNAL OF APPLIED PHYSICS》 20091117 Ming Li et al. Origin(s) of the apparent high permittivity in CaCu3Ti4O12 ceramics: clarification on the contributions from internal barrier layer capacitor and sample-electrode contact effects 104106 1-8 1-5 第106卷, 2 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105568383A (en) * 2016-01-06 2016-05-11 中国科学院上海光学精密机械研究所 Synthesis method of raw material for CaCuTi4O12 crystal growth and preparation method of CaCuTi4O12 crystal
CN109912305A (en) * 2019-04-25 2019-06-21 重庆大学 A kind of high-potential gracient, low-dielectric loss CaCu3Ti4O12Voltage-sensitive ceramic and preparation method thereof
CN109912305B (en) * 2019-04-25 2022-03-04 重庆大学 CaCu with high potential gradient and low dielectric loss3Ti4O12Pressure-sensitive ceramic and preparation method thereof
CN112521166A (en) * 2020-12-14 2021-03-19 江西科技学院 Low dielectric loss CaCu3Ti4O12Negative pressure sintering method of ceramic
CN113773055A (en) * 2021-10-15 2021-12-10 中国船舶重工集团公司第七二五研究所 Preparation method of metal oxide coating electrode

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Application publication date: 20100804