Summary of the invention
The object of the present invention is to provide a kind of KNN-LT leadless piezoelectric ceramics and preparation method thereof, the method technique is simple, energy consumption is low, cost is low, the chemical formula of obtained KNN-LT leadless piezoelectric ceramics is (1-x) (0.5KNbO
3-0.5NaNbO
3)-xLiTaO
3(x=0 ~ 0.10).
For achieving the above object, the technical solution used in the present invention is:
A kind of KNN-LT leadless piezoelectric ceramics, its chemical formula is:
(1-x) (0.5KNbO
3-0.5NaNbO
3)-xLiTaO
3, wherein x=0 ~ 0.10.
It is perovskite structure, its piezoelectric constant d
33=104 ~ 167pC/N, electromechanical coupling factor K
p=17.1 ~ 37.3%, mechanical quality factor Q
m=19.2 ~ 131.9, Curie temperature T
c=444.4 ~ 461.8 DEG C.
When x≤0.04, the principal crystalline phase of KNN-LT leadless piezoelectric ceramics is orthogonal perovskite structure; When x >=0.10, the principal crystalline phase of KNN-LT leadless piezoelectric ceramics is cubic perovskite structure.
A preparation method for KNN-LT leadless piezoelectric ceramics, comprises the following steps:
Step 1: by (1-x) (0.5KNbO
3-0.5NaNbO
3)-xLiTaO
3, the stoichiometric ratio of x=0 ~ 0.10, calculating K NbO
3powder, NaNbO
3powder and LiTaO
3the quality of powder also takes, and obtains raw material;
Step 2: reaction vessel put into by raw material step 1 taken, adds organic matter binding agent and water, and stirred at ambient temperature, to mixing and forming colloid, is then dried, and obtains batch mixing; The quality of the organic matter binding agent wherein added is 0.7% ~ 2.3% of raw materials quality, and the quality of the water added is 50 ~ 100% of raw materials quality;
Step 3: the water adding raw materials quality 3 ~ 5% in the batch mixing of step 2 gained, is placed in no light conditions old, then granulation after mixing, more dry-pressing formed, obtains ceramic green blank;
Step 4: ceramic green blank, through plastic removal process, at ambient pressure in 1060 ~ 1080 DEG C of sintering 2 ~ 3h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
With the KNbO of water heat transfer
3, NaNbO
3and LiTaO
3powder is raw material.
Organic binder bond in described step 2 is the sodium polyacrylate of the sodium alginate of raw materials quality 0.1% ~ 0.3%, the sodium humate of raw materials quality 0.5% ~ 1.5% and raw materials quality 0.1% ~ 0.5%.
Churning time in described step 2 is 1 ~ 2h, and bake out temperature is 60 ~ 80 DEG C.
The old time in described step 3 is 12 ~ 48h, and dry-pressing formed pressure is 20 ~ 30MPa.
The temperature of the plastic removal process in described step 4 is 600 ~ 700 DEG C;
In the sintering process of described step 4 around ceramic green blank with same constitutive material as buried powder to reduce the volatilization of alkali metal cation in sintering process.
Described KNN-LT leadless piezoelectric ceramics also needs to carry out polarization operations, and concrete steps are: by KNN-LT leadless piezoelectric ceramics by upper silver electrode, and in the silicone oil of 100 ~ 120 DEG C, polarize 30 ~ 60mins under 3 ~ 3.5kV/mm voltage.
Relative to prior art, beneficial effect of the present invention is:
The preparation method of KNN-LT leadless piezoelectric ceramics provided by the invention, with KNbO
3, NaNbO
3and LiTaO
3powder is raw material, theoretical according to diffusion double layer, utilize diffusion double layer principle batch mixing method, add organic matter binding agent and water to stir into stable colloid and make it mix, recycling dry pressing prepares ceramic green blank, in atmospheric conditions ceramic green blank is sintered again, obtained KNN-LT leadless piezoelectric ceramics, i.e. (1-x) (0.5KNbO
3-0.5NaNbO
3)-xLiTaO
3(x=0 ~ 0.10) leadless piezoelectric ceramics.Be that a kind of technique is simple, efficiency is high, energy consumption is low, with low cost and have very much a leadless piezoelectric ceramics preparation method of practicality.And obtained (1-x) (0.5KNbO
3-0.5NaNbO
3)-xLiTaO
3(x=0 ~ 0.10) leadless piezoelectric ceramics stable in properties, densification, functional.
Further, KNN-LT leadless piezoelectric ceramics provided by the invention is perovskite structure, has good piezoelectricity, ferroelectric properties, its piezoelectric constant d
33=104 ~ 167pC/N, electromechanical coupling factor K
p=17.1 ~ 37.3%, mechanical quality factor Q
m=19.2 ~ 131.9, Curie temperature T
c=444.4 ~ 461.8 DEG C.And the KNN-LT leadless piezoelectric ceramics (x=0.06) of accurate homotype phase boundary composition has better piezoelectricity, ferroelectric properties.
Further, the present invention in sintering process around ceramic green blank with same constitutive material as buried powder to reduce the volatilization of alkali metal cation in sintering process.
Embodiment
Below in conjunction with embodiment and accompanying drawing, the invention will be further described.
With the KNbO of water heat transfer in following examples
3, NaNbO
3and LiTaO
3powder is that KNN-LT leadless piezoelectric ceramics prepared by raw material, and wherein the concrete preparation method of each raw material is:
KNbO
3the Hydrothermal Synthesis of powder:
Weigh 13mol/L KOH, 0.5mol/L Nb
2o
5be dissolved in ionized water, magnetic agitation 1h, move in teflon-lined reactor, adding water to compactedness is hydro-thermal reaction 24h under 70%, 230 DEG C of constant temperature, naturally cools to room temperature, and with distilled water cleaning to neutral, at 80 DEG C, drying obtains KNbO
3powder.
NaNbO
3the Hydrothermal Synthesis of powder:
Weigh 6mol/L NaOH, 0.5mol/L Nb
2o
5be dissolved in ionized water, magnetic agitation 1h, move in teflon-lined reactor, adding water to compactedness is hydro-thermal reaction 24h under 70%, 230 DEG C of constant temperature, naturally cools to room temperature, and with distilled water cleaning to neutral, at 80 DEG C, drying obtains NaNbO
3powder.
LiTaO
3the Hydrothermal Synthesis of powder:
Weigh the Li of 0.2mol/L
2cO
3, 0.1mol/L Ta
2o
5, 0.40 ~ 0.61mol/L LiOHH
2o is dissolved in ionized water, magnetic agitation 1h, and move in teflon-lined reactor, adding water to compactedness is hydro-thermal reaction 36h under 70%, 240 DEG C of constant temperature, naturally cools to room temperature, and with distilled water cleaning to neutral, at 80 DEG C, drying obtains LiTaO
3powder.
Fig. 1 is the NaNbO of Hydrothermal Synthesis of the present invention
3, KNbO
3and LiTaO
3the XRD figure of powder.Wherein a is NaNbO
3the XRD figure of powder, NaNbO
3all diffraction peaks are consistent with PDF card (JCPDS NO.73-0803), and illustrate that it is orthorhombic phase, it is spacer Pbcm; B is KNbO
3the XRD figure of powder, KNbO
3the all diffraction peaks of powder are consistent with PDF card (JCPDS NO.71-0946), are orthorhombic phase structure, and it is spacer Amm2; C is LiTaO
3the XRD figure of powder, LiTaO
3the all diffraction peaks of powder are consistent with PDF card (JCPDS NO.71-0951), and be the rhombohedral structure extended along [111], its spacer is R-3c.
Embodiment 1:
Step 1: with the KNbO of water heat transfer
3powder and NaNbO
3powder is raw material, by 0.5KNbO
3-0.5NaNbO
3(x=0) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.15%, the sodium humate of raw materials quality 1.25% and raw materials quality 0.1%) and quality are 100% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1h to mixing and forming colloid; then the baking oven putting into 80 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 3% in the batch mixing of step 2 gained, old 24h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 25MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through plastic removal (binder removal) process of 700 DEG C, at ambient pressure in 1060 DEG C of sintering 2h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 120 DEG C, polarize 40mins under 3kV/mm voltage, after having polarized, places diel test ceramic performance.
Obtained ceramic performance: d
33=104pC/N, K
p=17.1%, Q
m=131.9, T
c=444.4 DEG C.
Embodiment 2:
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.475KNbO
3-0.475NaNbO
3-0.05LiTaO
3(x=0.05) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.18%, the sodium humate of raw materials quality 1.2% and raw materials quality 0.12%) and quality are 100% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1h to mixing and forming colloid; then the baking oven putting into 80 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 3% in the batch mixing of step 2 gained, old 24h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 25MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 700 DEG C, at ambient pressure in 1060 DEG C of sintering 2h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 120 DEG C, polarize 40mins under 3kV/mm voltage, after having polarized, places diel test ceramic performance.
Obtained ceramic performance: d
33=142pC/N, K
p=33.5%, Q
m=48.03, T
c=458.2 DEG C
Embodiment 3:
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.47KNbO
3-0.47NaNbO
3-0.06LiTaO
3(x=0.06) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.2%, the sodium humate of raw materials quality 1.15% and raw materials quality 0.15%) and quality are 100% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1h to mixing and forming colloid; then the baking oven putting into 80 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 3% in the batch mixing of step 2 gained, old 24h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 25MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 700 DEG C, at ambient pressure in 1060 DEG C of sintering 2h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 120 DEG C, polarize 40mins under 3kV/mm voltage, after having polarized, places diel test ceramic performance.
Obtained ceramic performance: d
33=167pC/N, K
p=37.3%, Q
m=19.2, T
c=461.8 DEG C
Embodiment 4:
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.465KNbO
3-0.465NaNbO
3-0.07LiTaO
3(x=0.07) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.25%, the sodium humate of raw materials quality 1% and raw materials quality 0.25%) and quality are 100% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1h to mixing and forming colloid; then the baking oven putting into 80 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 3% in the batch mixing of step 2 gained, old 24h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 25MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 700 DEG C, at ambient pressure in 1060 DEG C of sintering 2h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 120 DEG C, polarize 40mins under 3kV/mm voltage, after having polarized, places diel test ceramic performance.
Obtained ceramic performance: d
33=147pC/N, K
p=33.5%, Q
m=26.6, T
c=458.6 DEG C
Embodiment 5:
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.45KNbO
3-0.45NaNbO
3-0.1LiTaO
3(x=0.1) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.3%, the sodium humate of raw materials quality 0.8% and raw materials quality 0.4%) and quality are 100% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1h to mixing and forming colloid; then the baking oven putting into 80 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 3% in the batch mixing of step 2 gained, old 24h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 25MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 700 DEG C, at ambient pressure in 1060 DEG C of sintering 2h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 120 DEG C, polarize 40mins under 3kV/mm voltage, after having polarized, places diel test ceramic performance.
Obtained ceramic performance: d
33=121pC/N, K
p=23.9%, Q
m=42.9, T
c=455.6 DEG C
Fig. 2 is the XRD figure spectrum of KNN-LT leadless piezoelectric ceramics prepared by the present invention, and wherein a ~ e is respectively the XRD figure spectrum of KNN-LT leadless piezoelectric ceramics prepared by embodiment 1 ~ 5.Can find that from figure all KNN-LT leadless piezoelectric ceramics samples are at room temperature perovskite structure, not find obvious second-phase, illustrate that KNN-LT leadless piezoelectric ceramics defines sosoloid.According to swarming height relation near 45 °, can find, when x≤0.04, KNN-LT leadless piezoelectric ceramics principal crystalline phase is orthogonal perovskite structure; When x >=0.10, KNN-LT leadless piezoelectric ceramics principal crystalline phase is cubic perovskite structure.Therefore infer, under room temperature, the accurate homotype phase boundary of KNN-LT leadless piezoelectric ceramics appears at 0.04 < x < 0.10 place.
Fig. 3 is Jie's temperature collection of illustrative plates of KNN-LT leadless piezoelectric ceramics prepared by the present invention, and wherein a ~ e is respectively Jie's temperature collection of illustrative plates of KNN-LT leadless piezoelectric ceramics prepared by embodiment 1 ~ 5, and wherein ordinate zou represents relative permittivity.As can be seen from the figure, all KNN-LT leadless piezoelectric ceramics samples all show typical relative permittivity-temperature dependence, all have two dielectric peaks, respectively corresponding four directions-cube phase in version (T
c) phase in version (T in and orthogonal-four directions
o-T).Along with LiTaO
3the increase of content, the high-T_c superconductors point of KNN-LT leadless piezoelectric ceramics sample is to the translation of low temperature direction, and four directions-Emission in Cubic height is to the translation of high temperature direction simultaneously.As x=0.06, faint orthogonal-cubic dielectric peak can be observed in cold zone, and cold zone has not observed orthogonal-cubic dielectric peak when x>=0.07, show that near x=0.06, KNN-LT leadless piezoelectric ceramics sample interior exists accurate homotype phase boundary under room temperature, and KNN-LT leadless piezoelectric ceramics has higher Curie temperature, T near accurate homotype phase boundary
cup to 461.8 DEG C.
Fig. 4 is the SEM figure of KNN-LT leadless piezoelectric ceramics prepared by the present invention, and wherein a, b, c, d, e are respectively the SEM figure of KNN-LT leadless piezoelectric ceramics prepared by embodiment 1 ~ 5.As can be seen from the figure, pure KNN pottery is due to Na in sintering process
2o, K
2the a large amount of pore of O; With a large amount of pore of formation; Along with LT(LiTaO
3) increase of doping x, KNN-LT leadless piezoelectric ceramics sample interior pore first reduces rear increase, causes the change of KNN-LT leadless piezoelectric ceramics density first increases and then decreases.As LT doping x=0.06, KNN-LT leadless piezoelectric ceramics sample interior only has a small amount of Minute pores, and now sample density reaches the highest.
Embodiment 6
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.495KNbO
3-0.495NaNbO
3-0.01LiTaO
3(x=0.01) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken, adds organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.1%, the sodium humate of raw materials quality 0.5% and raw materials quality 0.1%) and quality is raw materials quality
The distilled water of 50%, adopt diffusion double layer principle batch mixing method, room temperature lower magnetic force stirs 2h to mixing and forming colloid, and the baking oven then putting into 60 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 4% in the batch mixing of step 2 gained, old 48h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 20MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 600 DEG C, at ambient pressure in 1070 DEG C of sintering 3h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 110 DEG C, polarize 30mins under 3.2kV/mm voltage.
Embodiment 7
Step 1: with the KNbO of water heat transfer
3powder, NaNbO
3powder and LiTaO
3powder is raw material, by 0.485KNbO
3-0.485NaNbO
3-0.03LiTaO
3(x=0.03) stoichiometric ratio, calculates required each powder quality and takes, obtaining raw material.
Step 2: beaker put into by raw material step 1 taken; add the distilled water that organic matter binding agent (being made up of the sodium polyacrylate of the sodium alginate of raw materials quality 0.18%, the sodium humate of raw materials quality 1.2% and raw materials quality 0.12%) and quality are 75% of raw materials quality; adopt diffusion double layer principle batch mixing method; room temperature lower magnetic force stirs 1.5h to mixing and forming colloid; then the baking oven putting into 70 DEG C is dried, and obtains batch mixing;
Step 3: the distilled water adding raw materials quality 5% in the batch mixing of step 2 gained, old 12h in no light conditions is placed on after mixing, then the particle of good fluidity is obtained through granulation, more dry-pressing formed under 30MPa pressure, obtain the ceramic green blank that diameter is about 10mm;
Step 4: ceramic green blank, through the plastic removal process of 650 DEG C, at ambient pressure in 1080 DEG C of sintering 2.5h, obtains KNN-LT leadless piezoelectric ceramics after cooling.
KNN-LT leadless piezoelectric ceramics is by upper silver electrode, and in the silicone oil of 100 DEG C, polarize 60mins under 3.5kV/mm voltage.
The foregoing is only one embodiment of the present invention, it not whole or unique embodiment, the conversion of those of ordinary skill in the art by reading specification sheets of the present invention to any equivalence that technical solution of the present invention is taked, is claim of the present invention and contains.