Two, background technology
Piezoceramic material is an important functional material, is widely used in transducer, piezoelectric transformer, fields such as filter and ultrasonic motor.Piezoelectric ceramic occupies quite great proportion as important functional material in field of electronic materials.In recent years, piezoelectric ceramic was pressed about 15% speed increment at global annual sales.According to statistics, global piezoelectric ceramic product sales reached more than 3,000,000,000 dollars approximately in 2000.But; Traditional piezoceramic material mainly is the lead base pottery, though it has piezoelectric property preferably, plumbous all have very big harm to environment and human health; With the PZT piezoelectric ceramic is example; Lead oxide accounts for more than 60% of its material content, in preparation, all can produce adverse influence to environment in use and the discarded reprocessing.Calendar year 2001, European Parliament passed through the decree about " limiting harmful substance in electrical equipment and the electronic equipment ", and implemented due to 2006.Wherein in the material that is limited to use, just comprise leaded piezoelectric device.This shows that the forbidding that contains lead piezoelectric ceramics is an inexorable trend, thereby lead-free environmentally friendly lead-free piezoceramic material becomes the focus of research.
Present lead-free piezoceramic material mainly contains BaTiO
3Base, Bi
1/2Na
1/2TiO
3(BNT) base, niobate, bismuth laminated leadless piezoelectric ceramic etc.Na wherein
05K
05NbO
3(being called for short KNN) piezoceramic material belongs to perovskite structure; Its Curie temperature is about 415 ℃; It under the room temperature oblique side's phase; Be regarded as one of candidate material that substitutes conventional P ZT piezoelectric ceramic, in a very long time both at home and abroad this side and research rest on simple system more, the piezoelectric property of material is not high yet.In people's such as the Saito Y of research institute of central authorities of Japanese Toyota research, obtained d
33At the niobate lead-free piezoelectric ceramics of 416pC/N, this has just caused people's attention again.But technology is too complicated, is difficult to be employed.Compare with the PZT piezoelectric ceramic, because potassium oxide and sodium oxide molybdena volatilize easily, preparation technology's property of KNN is poor, and when normal atmosphere was depressed sintering, the density of pottery had only 90% of solid density, short texture, and performance is undesirable.
The synthetic methods such as solid-phase synthesis, hydro thermal method, sol-gal process that mainly contain of piezoelectric ceramic powder.Solid-phase synthesis is a kind of traditional powder synthetic method, raw materials mix is pulverized behind high temperature solid state reaction and is obtained powder.The method has advantages such as cost is low, and technology is simple, but the method is difficult to make raw materials mix even, and particle slightly disperses, and to potassium-sodium niobate series leadless piezoelectric ceramics, the powder of the method preparation is difficult to sintering.Therefore, adopt the synthetic potassium-sodium niobate system lead-free piezoelectric ceramic powder of wet chemical method such as hydro thermal method and sol-gal process more and more to come into one's own.
That the superfine powder of Hydrothermal Preparation has is high-purity, ultra-fine, good fluidity, narrow diameter distribution, the particle agglomeration degree is light, crystal development is complete and the sintering activity advantages of higher.Simultaneously; The Hydrothermal Preparation powder is in liquid phase, once to accomplish; Do not need the heat treatment in later stage; Thereby avoided growing up voluntarily and sneaking into impurity etc. easily owing to hard aggregation, crystal grain that the later stage sintering produces powder, so the Hydrothermal Preparation ceramic powder is active to improving ceramic post sintering, reducing sintering temperature has very significance.Hydro thermal method has obtained in fields such as nano materials using widely in recent years; At present the synthetic potassium-sodium niobate powder preparing KNN series lead-free piezoelectric ceramic of hydro thermal method report very few, but (Takahashi H, Numamoto Y such as Takahashi; Tani J; Et al. [J] .Jpn J Appl Phys, 2006,45 (1-3): L30-L32.).With the synthetic BT lead-free piezoelectric ceramic powder of hydro thermal method, obtained the ceramic of compact that density reaches solid density 98.3%, electromechanical coupling factor has reached 36%; (Karaki T, YanK, Adachi M, [J] .Applied Physics Express, 2008 (1): 111402.) such as Karaki.Use the hydro-thermal powder to adopt two-step sintering method to prepare the BT piezoelectric ceramic of piezoelectric constant, shown good piezoelectric property as 460pC/N.Vousden (Vousden P, [J] .Acta Crystallogr, 1951,4:373-376.) at first with the synthetic NaNbO of hydro thermal method
3Powder, people such as Kinomura are with Na
8[Nb
6O
9] 13H
20 is raw material, is that mineralizer has prepared NaNbO with NaOH
3(Kinomura N, Kumata N, Muto F, [J] .Mat Res Bull, 1984,19:299-304.), human hydro thermal methods such as Santos have been synthesized the NaNbO of single-phase rhombic system
3Powder, and reported the differential responses time, different mol ratio to the influence of product (Santos I, Loureiro L, Silva M, et al. [J] .Polyhedron, 2002,21:2009-2015.).There has been in the recent period the researcher to begin to carry out the research of the synthetic pure phase KNN of hydro-thermal, and obtained preliminary progress (Zhang F, Han L, Bai S, et al. [J] .Jpn J Appl Phys, 2008.47 (9): 7685-7688.).But these preparation methods are one-step method.Because sodium ion radius (0.97
) less than potassium ion radius (1.33
); Sodium ion is faster than potassium ion with the niobium pentaoxide reaction speed under hydrothermal condition, when making the disposable hydro-thermal reaction of raw materials such as potassium hydroxide, NaOH and niobium pentaoxide, is easy to synthetic separately sodium niobate and potassium niobate; Mostly the powder that obtains is two-phase coexistent, is not easy to obtain the K that has of pure phase
0.5Na
0.5NbO
3The ceramic powder of composition.
The patent No. is the preparation method that 200610104948.7 Chinese invention patent discloses the substituted potassium niobate based leadless piezoelectric ceramics of a kind of tantalum, and the general formula of the substituted potassium niobate based leadless piezoelectric ceramics of its tantalum is (K
0.44Na
0.52Li
0.04) (Nb
0.96-xTa
xSb
0.04) O
3, 0.00≤x≤0.40.This method is a kind of solid-phase synthesis.
Three, summary of the invention
1, technical problem: the technical problem that the present invention will solve provides the potassium-sodium niobate lead-free ceramic material of a kind of lithium, antimony and tantalum codope, and two one-step hydro-thermal synthesis methods of the potassium-sodium niobate lead-free ceramic material of a kind of lithium, antimony and tantalum codope are provided simultaneously,
2, technical scheme: in order to solve above-mentioned technical problem, the molecular formula of the potassium-sodium niobate lead-free ceramic material of lithium of the present invention, antimony and tantalum codope is [(K
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10).
Two one-step hydro-thermal synthesis methods of the potassium-sodium niobate lead-free ceramic material of lithium of the present invention, antimony and tantalum codope comprise the following steps:
Step 1: compound concentration is potassium hydroxide, the NaOH of 2M~10M, and lithium hydroxide solution, and preparation basicity is the potassium hydroxide of 2~10M and the mixed liquor that the lithium hydroxide mol ratio is 10: 1~100: 1;
Step 2: adopt potassium hydroxide and the mixed liquor of lithium hydroxide and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4~2: 3 of step 1, pour in the polytetrafluoroethyllining lining of stainless steel hydrothermal reaction kettle, the maintenance compactedness is 20%-80%;
Step 3: take by weighing niobium pentaoxide, antimony pentoxide and tantalum pentoxide powder, pour in the mixed solution of step 2, stirred 5~60 minutes, the mol ratio of niobium pentaoxide, antimony pentoxide and tantalum pentoxide is 1: 1: 8~8: 1: 1;
Step 4: with the polytetrafluoroethyllining lining of the step 2 stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 160 ℃~300 ℃, and the time is 4~36 hours, obtains sediment;
Step 5: the sediment that step 4 obtains is extremely neutral with the deionized water vacuum filtration; The filter cake that obtains descended dry 24~48 hours 60~100 ℃ of temperature, obtained the powder of good dispersion;
Step 1 to five prepares the dispersed potassium niobate powder of lithium, antimony, tantalum codope preferably.
Step 6: adopt the sodium hydroxide solution of step 1 and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4~2: 3, pour in the polytetrafluoroethyllining lining of stainless steel hydrothermal reaction kettle, keeping compactedness is 20%~80%;
Step 7: take by weighing the powder that step 5 obtains and pour in the mixed solution of step 6, mechanical agitation 5~60 minutes guarantees that the NaOH mol ratio in powder and the solution is 2: 1~1: 1;
Step 8: with the polytetrafluoroethyllining lining stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 160 ℃~300 ℃, and the time is 4~36 hours, obtains sediment;
Step 9: the sediment that step 8 obtains is extremely neutral with the deionized water vacuum filtration; [(the K that the filter cake that obtains in 80 ℃ of dry down molecular formula that obtained good dispersion, lithium antimony tantalum codope in 24 hours of temperature is
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10) lead-free piezoceramic material.
The synthetic potassium-sodium niobate that obtains lithium, antimony and tantalum codope of the potassium niobate powder of the lithium that step 6 to nine obtains through step 5, antimony, tantalum codope.
Method of the present invention can be considered the synthetic lead-free piezoceramic material method of hydro-thermal of two-step method.The first step is a raw material with potassium hydroxide, lithium hydroxide, niobium pentaoxide, antimony pentoxide and tantalum pentoxide, isopropyl alcohol auxiliary water thermal response, the potassium niobate powder of synthetic antimony, tantalum codope; Second step was raw material with NaOH with the synthetic powder of the first step again, isopropyl alcohol auxiliary water thermal response, synthetic the potassium-sodium niobate [(K that obtains antimony and tantalum codope
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10) powder; Above-mentioned isopropyl alcohol helps in the hydro-thermal reaction, and the volume ratio of isopropyl alcohol and water is 3: 2.
3, beneficial effect:
As shown in Figure 2; Adopt that the synthetic potassium-sodium niobate system lead-free piezoelectric ceramic powder of two one-step hydro-thermal synthesis methods provided by the invention has high-purity, ultra-fine, good fluidity, narrow diameter distribution, the particle agglomeration degree is light, crystal development is complete and the sintering activity advantages of higher; Be convenient to sintered leadless free piezoelectric ceramic at a lower temperature; Thereby avoid the volatilization of oxide such as potassium oxide and sodium oxide molybdena in the sintering process, finally realize the raising of potassium-sodium niobate system leadless piezoelectric ceramics piezoelectric property and mechanical performance; While two one-step hydro-thermal synthesis methods provided by the invention can synthesize accurate molecular formula and be [(K
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, the lead-free piezoelectric ceramic powder of (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10), the piezoelectric ceramic with these molecular formula is because its composition is in accurate homotype phase boundary region, and piezoelectric activity is the highest; The equipment that two one-step hydro-thermal synthesis methods provided by the invention adopt is simple, and operation is prone to row, and synthesis condition is gentle, is convenient to suitability for industrialized production.
Five, embodiment
Embodiment 1:
Present embodiment relates to a kind of preparation method of lead-free piezoceramic material, comprises the following steps:
Step 1: compound concentration is potassium hydroxide, the NaOH of 10M, and lithium hydroxide solution, and preparation basicity is the potassium hydroxide of 10M and the mixed liquor that the lithium hydroxide mol ratio is 10: 1;
Step 2: adopt potassium hydroxide and the mixed liquor of lithium hydroxide and the mixed solution that isopropyl alcohol configuration volume ratio is 2: 3 of step 1, pour in the polytetrafluoroethyllining lining 11 of stainless steel hydrothermal reaction kettle 1 as shown in Figure 1, keeping compactedness is 20%;
Step 3: take by weighing niobium pentaoxide, antimony pentoxide and tantalum pentoxide powder, pour in the mixed solution of step 2, stirred 30 minutes, the mol ratio of niobium pentaoxide, antimony pentoxide and tantalum pentoxide is 1: 1: 8;
Step 4: with the polytetrafluoroethyllining lining of the step 2 stainless steel hydrothermal reaction kettle 1 of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 160 ℃, and the time is 10 hours, obtains sediment;
Step 5: the sediment that step 4 obtains is extremely neutral with the deionized water vacuum filtration; The filter cake that obtains obtains the powder of good dispersion 60 times dryings of temperature 24 hours;
Step 1 to five prepares the dispersed potassium niobate powder of lithium, antimony, tantalum codope preferably.
Step 6: adopt the sodium hydroxide solution of step 1 and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4, pour in the polytetrafluoroethyllining lining 11 of stainless steel hydrothermal reaction kettle 1 as shown in Figure 1, keeping compactedness is 50%;
Step 7: take by weighing the powder that step 5 obtains and pour in the mixed solution of step 6, mechanical agitation 30 minutes guarantees that the NaOH mol ratio in powder and the solution is 2: 1;
Step 8: with the polytetrafluoroethyllining lining stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 160 °, and the time is 24 hours, obtains sediment;
Step 9: the sediment that step 8 obtains is extremely neutral with the deionized water vacuum filtration; [(the K that the filter cake that obtains in 80 ℃ of dry down molecular formula that obtained good dispersion, lithium antimony tantalum codope in 24 hours of temperature is
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10) lead-free piezoceramic material.
The synthetic potassium-sodium niobate that obtains lithium, antimony and tantalum codope of the potassium niobate powder of the lithium that step 6 to nine obtains through step 5, antimony, tantalum codope.
Embodiment 2:
Step 1: compound concentration is potassium hydroxide, the NaOH of 2M, and lithium hydroxide solution, and preparation basicity is the mixed liquor that 2 potassium hydroxide and lithium hydroxide mol ratio are 100: 1;
Step 2: adopt potassium hydroxide and the mixed liquor of lithium hydroxide and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4 of step 1, pour in the polytetrafluoroethyllining lining 11 of stainless steel hydrothermal reaction kettle 1, keeping compactedness is 80%;
Step 3: take by weighing niobium pentaoxide, antimony pentoxide and tantalum pentoxide powder, pour in the mixed solution of step 2, stirred 60 minutes, the mol ratio of niobium pentaoxide, antimony pentoxide and tantalum pentoxide is 8: 1: 1;
Step 4: with the polytetrafluoroethyllining lining of the step 2 stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 300 ℃, and the time is 36 hours, obtains sediment;
Step 5: the sediment that step 4 obtains is extremely neutral with the deionized water vacuum filtration; The filter cake that obtains descended dry 48 hours 80 ℃ of temperature, obtained the powder of good dispersion;
Step 1 to five prepares the dispersed potassium niobate powder of lithium, antimony, tantalum codope preferably.
Step 6: adopt the sodium hydroxide solution of step 1 and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4, pour in the polytetrafluoroethyllining lining of stainless steel hydrothermal reaction kettle, keeping compactedness is 80%;
Step 7: take by weighing the powder that step 5 obtains and pour in the mixed solution of step 6, mechanical agitation 60 minutes guarantees that the NaOH mol ratio in powder and the solution is 1: 1;
Step 8: with the polytetrafluoroethyllining lining stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 300 ℃, and the time is 36 hours, obtains sediment;
Step 9: the sediment that step 8 obtains is extremely neutral with the deionized water vacuum filtration; [(the K that the filter cake that obtains in 80 ℃ of dry down molecular formula that obtained good dispersion, lithium antimony tantalum codope in 24 hours of temperature is
0.5Na
0.5)
1-xLi
x] (Nb
1-y-zTa
ySb
z) O
3, (x=0.01~0.10, y=0.01~0.20, z=0.01~0.10) lead-free piezoceramic material.
The synthetic potassium-sodium niobate that obtains lithium, antimony and tantalum codope of the potassium niobate powder of the lithium that step 6 to nine obtains through step 5, antimony, tantalum codope.
Embodiment 3:
Step 1: compound concentration is potassium hydroxide, the NaOH of 5M, and lithium hydroxide solution, and preparation basicity is the mixed liquor that 2 potassium hydroxide and lithium hydroxide mol ratio are 80: 1;
Step 2: adopt potassium hydroxide and the mixed liquor of lithium hydroxide and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 3 of step 1, pour in the polytetrafluoroethyllining lining 11 of stainless steel hydrothermal reaction kettle 1, keeping compactedness is 80%;
Step 3: take by weighing niobium pentaoxide, antimony pentoxide and tantalum pentoxide powder, pour in the mixed solution of step 2, stirred 60 minutes, the mol ratio of niobium pentaoxide, antimony pentoxide and tantalum pentoxide is 2: 1: 2;
Step 4: with the polytetrafluoroethyllining lining of the step 2 stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 300 ℃, and the time is 36 hours, obtains sediment;
Step 5: the sediment that step 4 obtains is extremely neutral with the deionized water vacuum filtration; The filter cake that obtains descended dry 48 hours 80 ℃ of temperature, obtained the powder of good dispersion;
Step 1 to five prepares the dispersed potassium niobate powder of lithium, antimony, tantalum codope preferably.
Step 6: adopt the sodium hydroxide solution of step 1 and the mixed solution that isopropyl alcohol configuration volume ratio is 1: 4, pour in the polytetrafluoroethyllining lining of stainless steel hydrothermal reaction kettle, keeping compactedness is 80%;
Step 7: take by weighing the powder that step 5 obtains and pour in the mixed solution of step 6, mechanical agitation 60 minutes guarantees that the NaOH mol ratio in powder and the solution is 1: 1;
Step 8: with the polytetrafluoroethyllining lining stainless steel hydrothermal reaction kettle of packing into, put into baking oven and carry out hydro-thermal reaction, temperature is 300 ℃, and the time is 36 hours, obtains sediment;
Step 9: the sediment that step 8 obtains is extremely neutral with the deionized water vacuum filtration; The filter cake that obtains is (K in 80 ℃ of dry down molecular formula that obtained good dispersion, lithium antimony tantalum codope in 24 hours of temperature
0.74Na
0.26) (Nb
0.9Sb
0.1) O
3) lead-free piezoceramic material.
The synthetic potassium-sodium niobate that obtains lithium, antimony and tantalum codope of the potassium niobate powder of the lithium that step 6 to nine obtains through step 5, antimony, tantalum codope.
As shown in Figure 2, it is complete to find out that lead-free piezoelectric ceramic powder that the present embodiment method prepares has crystal development, advantages such as the particle agglomeration degree is light, good fluidity.