A kind of low temperature sintering lithium-base microwave dielectric ceramic material and preparation method thereof
Technical field
The invention belongs to electronic ceramics and preparation field thereof, relate in particular to a kind of low temperature sintering lithium-base microwave dielectric ceramic material and preparation method thereof.
Background technology
Microwave-medium ceramics refers to and is applied to microwave frequency band, be mainly in the circuit of UHF, SHF frequency range as dielectric material and complete the stupalith of one or more functions, be the critical material of the microwave devices such as widely used resonator in modern communications field, wave filter, medium substrate, medium guided wave loop.Along with electronic information technology is constantly to high frequency and digitizing future development, miniaturization, integrated and modular requirement to components and parts are day by day urgent, LTCC LTCC(LowTemperature Co-firedCeramics) technology is because of its excellent electricity, machinery, calorifics, operational characteristic and high reliability, become one of major technique of electronic-component module.Compared with other integrated technology, it is low that LTCC technology has sintering temperature, the low metal of available resistivity, as the conductor material of multilayer wiring, can improve packing density, signaling rate, and can in be embedded in the advantages such as the various laminar microwave electronic devices of multilager base plate once-firing.LTCC Technology Need microwave-medium ceramics can burn altogether with electrode in the metal A g of high conductivity low melting point, Cu, and therefore, the low-temperature sintering of microwave dielectric ceramic materials has become study hotspot.Although the microwave-medium ceramics of most of commercial has good microwave dielectric property, its sintering temperature very high (generally higher than 1200 ℃), therefore must research and develop microwave-medium ceramics that intrinsic sintering temperature is lower to meet the requirement of LTCC technique.
Li
2aTi
3o
8the sintering temperature of (A=Zn, Mg, Co, the one in Ni ion) base pottery is conventionally 1100 ℃ of left and right, is the grow a lot lower microwave-medium ceramics system of intrinsic sintering temperature of potentiality of a kind of tool.2010, people's reported first such as S.George Li
2znTi
3o
8and Li
2mgTi
3o
8the sintering characteristic of system and microwave dielectric property.2011, people's reported first such as FangLiang Li
2coTi
3o
8the sintering characteristic of system and microwave dielectric property.The pottery of these systems all has lower sintering temperature and excellent microwave dielectric property, and after calcining, is passing through to add a small amount of sintering aid as B
2o
3, Bi
2o
3, ZnO-B
2o
3glass powder, ZnO-B
2o
3-SiO
2glass powder and ZnO-La
2o
3-B
2o
3glass powder etc., can be reduced to 900 ℃ of left and right by their final sintering temperature, have met the requirement of LTCC Technology.But due to the density that adds membership reduction stupalith of sintering aid, therefore its microwave dielectric property can decline more.
At present when the above-mentioned lithium-based microwave media ceramic of preparation, employing be all traditional solid sintering technology, the method technological process is more complicated, need through calcining+final two stages of sintering, sintering time is longer, and energy consumption is higher, and because process procedure is more, easily bring impurity into, thereby affect the performance of material.Reaction sintering is a kind of simple sintering method, the reaction of raw material powder and densification realize in once sintered process, have saved calcining and secondary ball milling operation in traditional preparation method, can simplify preparation section, reduce production costs and energy consumption, reduce the impurity of bringing in production process.Because powder in reaction sintering does not pass through calcination stage, while therefore adopting reaction sintering to prepare higher ceramic of density, the having relatively high expectations of the purity to material powder and granularity, or need high temperature of reaction.Prepare single-phase Li when adopting reaction sintering
2aTi
3o
8in (A=Zn, Mg, Co, the one in Ni ion) base when pottery,, because temperature of reaction is higher, Li, Zn element are volatile, produce pore, and Li in sintering process
2cO
3raw material decomposes generation CO
2gas can reduce the density of sintered compact, the single-phase Li that therefore adopts reaction sintering directly to prepare
2aTi
3o
8(A=Zn, Mg, Co, the one in Ni ion) base ceramic dense degree is generally lower, causes its microwave dielectric property also to decline accordingly.Along with developing rapidly of modern communications technology, design a kind of microwave dielectric property excellence, low temperature sintering lithium-base microwave dielectric ceramic material that quality stability is good and preparation method thereof, to meet the need of market, is very important.
Summary of the invention
The technical problem solving:
The application is higher for the complex process existing in prior art, energy consumption, microwave dielectric property and the technical problem such as quality stability is poor, and a kind of low temperature sintering lithium-base microwave dielectric ceramic material and preparation method thereof is provided.
Technical scheme:
A kind of low temperature sintering lithium-base microwave dielectric ceramic material, the chemical constitution expression formula of its formula is: Li
2aTi
3o
8+ B
2o
3, wherein A is Zn, Mg, Co, the one in Ni ion, described B
2o
3addition be equivalent to Li
2aTi
3o
8xwt%, wherein 1.0≤x≤2.5.
A preparation method for low temperature sintering lithium-base microwave dielectric ceramic material, step is:
The first step, batching: by Li
2cO
3, AO and TiO
2powder is by formula general formula Li
2aTi
3o
8stoichiometric ratio preparation base-material, wherein A is Zn, Mg, Co, the one in Ni ion, then directly adds the B that is equivalent to base-material weight 1%~2.5%
2o
3powder, obtains compound;
Second step, ball milling: compound is placed in to planetary ball mill wet ball grinding 12~24 hours, and described planetary ball mill rotating speed is 300rpm;
The 3rd step, adds forming agent, granulation: the polyvinyl alcohol water solution that the concentration that adds compound weight 5~8wt% is 5wt%, the granulation of sieving after being dried;
The 4th step, compression moulding: on pressing machine, be pressed into base substrate with the pressure of 100~150MPa;
The 5th step, remove forming agent, sintering: base substrate is risen to 550 ℃ and be incubated 4 hours to remove polyvinyl alcohol forming agent with the temperature rise rate of 1.5 ℃/min in high-temperature box type electric furnace, be warming up to subsequently 800~900 ℃ of sintering 4~8 hours, obtain low temperature sintering lithium-base microwave dielectric ceramic material.
As a preferred technical solution of the present invention: sieving in described the 3rd step is to sieve through 40-60 object screen cloth.
As a preferred technical solution of the present invention: in described the 4th step, base substrate is shaped as right cylinder.
Beneficial effect:
Compared to the prior art a kind of low temperature sintering lithium-base microwave dielectric ceramic material of the present invention and preparation method thereof adopts above technical scheme, there is following technique effect: 1, technological process simple, saved calcining and secondary ball milling operation in traditional preparation method, simplify preparation section, reduce production costs and energy consumption, and reduce the impurity of bringing in production process; 2, cheap, the sintering temperature of raw materials cost is lower than 900 ℃; 3, B in sintering process
2o
3directly mix B with raw material powder
2o
3in reaction sintering process subsequently with raw material in Li
2cO
3form eutectic compound with the powdered reaction such as ZnO, form at a lower temperature liquid phase, not only shorten the distance of material diffusion, promote the synthetic of principal crystalline phase, and residual pore after can blanketing gas overflowing, the carrying out that promotes densification process, finally can obtain the ceramic product of high-compactness by low temperature reaction sintering, and in product, there is no the generation of second-phase; 4, product microwave dielectric property excellence, relative permittivity ε
r22~26.5 interior adjustable, quality factor q f is 21000~63400GHz, temperature coefficient of resonance frequency τ
fadjustable in-16.0~7.0ppm/ ℃; 5, product microwave dielectric property and quality stability are good, can be applied to and manufacture chip multilayer microwave device, thereby the not division of history into periods of widespread production is for current material.
Embodiment:
Further illustrate technique effect of the present invention below in conjunction with example.
Table 1 is the compound of 12 kinds of component prescriptions.
The composition proportion of 12 kinds of compounds of table 1
Embodiment 1:
The first step: by Li
2cO
3, AO and TiO
2powder is by formula general formula Li
2aTi
3o
8stoichiometric ratio preparation base-material, wherein A is Zn, Mg, Co, the one in Ni ion, then requires to add B according to composition described in table 1
2o
3powder, obtains compound;
Second step: compound is placed in to planetary ball mill wet ball grinding 12 hours, and described planetary ball mill rotating speed is 300rpm;
The 3rd step: the polyvinyl alcohol water solution that the concentration that adds compound weight 5wt% is 5wt%, the dry rear 40-60 eye mesh screen granulation of crossing;
The 4th step: on pressing machine, be pressed into right cylinder base substrate with the pressure of 100MPa;
The 5th step: base substrate is risen to 550 ℃ and be incubated 4 hours to remove polyvinyl alcohol forming agent with the temperature rise rate of 1.5 ℃/min in high-temperature box type electric furnace, be warming up to subsequently 800 ℃ of sintering 8 hours, obtain low temperature sintering lithium-base microwave dielectric ceramic material.
Under above-mentioned preparation process condition, be prepared into lithium-based microwave media ceramic, and measured respectively its DIELECTRIC CONSTANT ε
r, quality factor q f value and temperature coefficient of resonance frequency τ
f, the microwave dielectric property of the lithium-based microwave media ceramic of heterogeneity proportioning is in table 2.
Table 2 adopts embodiment 1 to prepare the microwave dielectric property of different lithium base microwave dielectric ceramics
Embodiment 2:
The first step: by Li
2cO
3, AO and TiO
2powder is by formula general formula Li
2aTi
3o
8stoichiometric ratio preparation base-material, wherein A is Zn, Mg, Co, the one in Ni ion, then requires to add B according to composition described in table 1
2o
3powder, obtains compound;
Second step: compound is placed in to planetary ball mill wet ball grinding 24 hours, and described planetary ball mill rotating speed is 300rpm;
The 3rd step: the polyvinyl alcohol water solution that the concentration that adds compound weight 8wt% is 5wt%, the dry rear 40-60 eye mesh screen granulation of crossing;
The 4th step: on pressing machine, be pressed into right cylinder base substrate with the pressure of 150MPa;
The 5th step: base substrate is risen to 550 ℃ and be incubated 4 hours to remove polyvinyl alcohol forming agent with the temperature rise rate of 1.5 ℃/min in high-temperature box type electric furnace, be warming up to subsequently 900 ℃ of sintering 4 hours, obtain low temperature sintering lithium-base microwave dielectric ceramic material.
Under above-mentioned preparation process condition, be prepared into lithium-based microwave media ceramic, and measured respectively its DIELECTRIC CONSTANT ε
r, quality factor q f value and temperature coefficient of resonance frequency τ
f, the microwave dielectric property of the lithium-based microwave media ceramic of heterogeneity proportioning is in table 3.
Table 3 adopts embodiment 2 to prepare the microwave dielectric property of different lithium base microwave dielectric ceramics
Embodiment 3:
The first step: by Li
2cO
3, AO and TiO
2powder is by formula general formula Li
2aTi
3o
8stoichiometric ratio preparation base-material, wherein A is Zn, Mg, Co, the one in Ni ion, then requires to add B according to composition described in table 1
2o
3powder, obtains compound;
Second step: compound is placed in to planetary ball mill wet ball grinding 20 hours, and described planetary ball mill rotating speed is 300rpm;
The 3rd step: the polyvinyl alcohol water solution that the concentration that adds compound weight 6wt% is 5wt%, the dry rear 40-60 eye mesh screen granulation of crossing;
The 4th step: on pressing machine, be pressed into right cylinder base substrate with the pressure of 120MPa;
The 5th step: base substrate is risen to 550 ℃ and be incubated 4 hours to remove polyvinyl alcohol forming agent with the temperature rise rate of 1.5 ℃/min in high-temperature box type electric furnace, be warming up to subsequently 850 ℃ of sintering 6 hours, obtain low temperature sintering lithium-base microwave dielectric ceramic material.
Under above-mentioned preparation process condition, be prepared into lithium-based microwave media ceramic, and measured respectively its DIELECTRIC CONSTANT ε
r, quality factor q f value and temperature coefficient of resonance frequency τ
f, the microwave dielectric property of the lithium-based microwave media ceramic of heterogeneity proportioning is in table 4.
Table 4 adopts embodiment 3 to prepare the microwave dielectric property of different lithium base microwave dielectric ceramics
By the contrast of between table 1, table 2, table 3 and table 4, can draw:
1,, in the time that in lithium-based microwave media ceramic, A is Zn, the dielectric loss of gained lithium-based microwave media ceramic is relatively low.
2, in the time that in lithium-based microwave media ceramic, A is Co and Ni, the temperature coefficient of resonance frequency relatively nearly zero of gained lithium-based microwave media ceramic.
3, sintering temperature is relatively large on the impact of microwave dielectric property, and in the time of the sintering temperature value of mediating, when being 850 ℃, the ceramic dielectric loss of above-mentioned formula is relatively low.
Above-described embodiment is just for content of the present invention is set forth, rather than restriction, and therefore any change in implication and the scope suitable with claims of the present invention, all should think to be included in the scope of claims.