CN103864147B - A kind of potassium niobate powder and preparation method thereof - Google Patents
A kind of potassium niobate powder and preparation method thereof Download PDFInfo
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- CN103864147B CN103864147B CN201210544546.4A CN201210544546A CN103864147B CN 103864147 B CN103864147 B CN 103864147B CN 201210544546 A CN201210544546 A CN 201210544546A CN 103864147 B CN103864147 B CN 103864147B
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- UKDIAJWKFXFVFG-UHFFFAOYSA-N potassium;oxido(dioxo)niobium Chemical compound [K+].[O-][Nb](=O)=O UKDIAJWKFXFVFG-UHFFFAOYSA-N 0.000 title claims abstract description 67
- 239000000843 powder Substances 0.000 title claims abstract description 31
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 239000000243 solution Substances 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 25
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 24
- 239000007864 aqueous solution Substances 0.000 claims abstract description 18
- 239000007787 solid Substances 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 9
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 238000000926 separation method Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 61
- 230000003068 static effect Effects 0.000 claims description 10
- 239000002245 particle Substances 0.000 abstract description 21
- 238000009826 distribution Methods 0.000 abstract description 17
- 238000002425 crystallisation Methods 0.000 abstract description 12
- 230000008025 crystallization Effects 0.000 abstract description 12
- 238000005054 agglomeration Methods 0.000 abstract description 11
- 230000002776 aggregation Effects 0.000 abstract description 11
- 238000004458 analytical method Methods 0.000 abstract description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 222
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 29
- 239000010955 niobium Substances 0.000 description 28
- 239000012071 phase Substances 0.000 description 18
- 239000008367 deionised water Substances 0.000 description 17
- 229910021641 deionized water Inorganic materials 0.000 description 17
- 238000002441 X-ray diffraction Methods 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 11
- 239000002994 raw material Substances 0.000 description 11
- 238000005406 washing Methods 0.000 description 11
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 10
- 238000004140 cleaning Methods 0.000 description 9
- 238000003756 stirring Methods 0.000 description 9
- 238000001816 cooling Methods 0.000 description 8
- 239000011259 mixed solution Substances 0.000 description 8
- 238000002156 mixing Methods 0.000 description 7
- 238000007789 sealing Methods 0.000 description 7
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000013019 agitation Methods 0.000 description 2
- 238000007605 air drying Methods 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 235000011194 food seasoning agent Nutrition 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000010977 jade Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- LUMVCLJFHCTMCV-UHFFFAOYSA-M potassium;hydroxide;hydrate Chemical compound O.[OH-].[K+] LUMVCLJFHCTMCV-UHFFFAOYSA-M 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 238000001778 solid-state sintering Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000010189 synthetic method Methods 0.000 description 1
- 238000002076 thermal analysis method Methods 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention discloses a kind of preparation method of potassium niobate powder, the method comprises Nb
2o
5join in the KOH aqueous solution, the solution mixed is carried out Hydrothermal Synthesis, solid-liquid separation is carried out to the product of Hydrothermal Synthesis gained, and drying obtains solid.By aforesaid method provided by the invention, compared with prior art, can obtain purity higher, size distribution is narrower, and particle agglomeration degree is comparatively light, crystallization degree higher (by the analysis degree of crystallinity of XRD result more than 95%) potassium niobate powder.
Description
Technical field
The present invention relates to a kind of preparation method of potassium niobate powder, and the potassium niobate powder prepared by the method.
Background technology
Potassium niobate possesses special character in such as sense of hearing optics, electron optics, nonlinear optics and piezoelectricity, often as frequency converting material important in waveguide and holographic storage medium.Simultaneously in the application aspect of nano-machine electronic system and the sensor of unleaded and biocompatibility, all serve very important effect.And potassium niobate shows unique and superior performance, especially for the control of environmental pollution and green energy resource aspect as heterogeneous catalyst in recent years.
At present, the preparation method of potassium niobate mainly contains solid phase method, oligometric comples method, sol-gel method, hydrothermal synthesis method etc.Solid state sintering is generally difficult to raw material is mixed, and sintering temperature is high, is difficult to synthesize homogeneous niobium acid potassium crystal.Oligometric comples method employs large amount of organic and makes mass loss in roasting process very large, and the consumption of raw material and pH value have considerable influence to the formation of product and performance, so condition is not easy to control.Sol-gel method employs the alkoxide of extremely unstable, expensive, and preparation process conditional is comparatively harsh, and reaction and operation all must be carried out in the nitrogen atmosphere of drying.And Hydrothermal Synthesis rule is a gentle synthetic method, have product composition evenly, particle size distribution is narrow, crystallization degree advantages of higher.And the different crystalline phases of potassium niobate have a great impact for its catalytic performance tool.Therefore seek to utilize the hydrothermal synthesis method of mild condition high to synthesize purity, narrow diameter distribution, particle agglomeration mild degree, the potassium niobate that crystallization degree is high and crystalline phase is controlled becomes the focus in potassium niobate synthesis field.
Summary of the invention
The object of this invention is to provide a kind of preparation method of potassium niobate powder, and the purity prepared by the method is high, narrow diameter distribution, particle agglomeration mild degree, potassium niobate powder that crystallization degree is high.
The present inventor is found by a large amount of experiments, limits feeding sequence, by Nb
2o
5add in KOH solution, the solution mixed is carried out Hydrothermal Synthesis, contributes to KNbO like this
3the nucleation of crystal and growth.
The invention provides a kind of preparation method of potassium niobate powder, wherein, the method comprises Nb
2o
5join in the KOH aqueous solution, the solution mixed is carried out Hydrothermal Synthesis, solid-liquid separation is carried out to the product of Hydrothermal Synthesis gained, and drying obtains solid.
Present invention also offers the potassium niobate powder obtained by aforesaid method.
According to technique scheme, by limiting feeding sequence, by Nb
2o
5add in KOH solution, and carry out Hydrothermal Synthesis, by aforesaid method provided by the invention, compared with prior art, purity can be obtained higher, size distribution is narrower (as shown in Figure 5, the size distribution of 500-800nm reaches 67%), particle agglomeration degree is comparatively light, crystallization degree higher (by the analysis degree of crystallinity of XRD result more than 95%) potassium niobate powder, in addition, by control KOH and Nb
2o
5molar ratio, different crystalline phase, potassium niobate that crystallization degree is high can be obtained.
Under preferable case of the present invention, consider that KOH is as water content during raw material, and accurately control the concentration of KOH solution, purity and the better potassium niobate powder of degree of crystallinity can be obtained.
Under the further preferable case of the present invention, the present inventor finds Nb
2o
5join after in the KOH aqueous solution and the solution mixed is carried out Hydrothermal Synthesis under static conditions, than being more conducive to obtaining the better potassium niobate powder of degree of crystallinity under the agitation condition of prior art.
Other features and advantages of the present invention are described in detail in embodiment part subsequently.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification sheets, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:
Fig. 1 is the KNbO of the orthorhombic phase that embodiment 1 prepares
3sEM (scanning electronic microscope) photo of powder;
Fig. 2 is the KNbO of the orthorhombic phase that embodiment 1 prepares
3the constituency image of TEM (high resolution transmission electron microscopy) photo of powder;
Fig. 3 is the KNbO of the Emission in Cubic that embodiment 2 prepares
3sEM (scanning electronic microscope) photo of powder;
Fig. 4 is the KNbO of the Emission in Cubic that embodiment 2 prepares
3the constituency image of TEM (high resolution transmission electron microscopy) photo of powder;
Fig. 5 is the KNbO of the Emission in Cubic that embodiment 2 prepares
3the grain size distribution of powder;
Fig. 6 is the KNbO of the orthorhombic phase for preparing of embodiment 1 and embodiment 2 and Emission in Cubic
3the XRD spectra of powder;
Fig. 7 is the KNbO of the orthorhombic phase that embodiment 6 prepares
3sEM (scanning electronic microscope) photo of powder;
Fig. 8 is the KNbO of the orthorhombic phase that embodiment 6 prepares
3the XRD spectra of powder;
Fig. 9 is the KNbO that comparative example 1 prepares
3sEM (scanning electronic microscope) photo of powdered sample;
Figure 10 is the KNbO that comparative example 1 prepares
3the XRD spectra of powder.
Figure 11 is the KNbO that comparative example 2 prepares
3sEM (scanning electronic microscope) photo of powdered sample;
Figure 12 is the KNbO that comparative example 2 prepares
3the XRD spectra of powder.
Figure 13 is the KNbO that comparative example 3 prepares
3sEM (scanning electronic microscope) photo of powdered sample;
Figure 14 is the KNbO that comparative example 3 prepares
3the XRD spectra of powder.
Embodiment
Below the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.
The invention provides a kind of preparation method of potassium niobate powder, wherein, the method comprises Nb
2o
5join in the KOH aqueous solution, the solution mixed is carried out Hydrothermal Synthesis, solid-liquid separation is carried out to the product of Hydrothermal Synthesis gained, and drying obtains solid.
According to the present invention, first obtain KOH solution, then by Nb
2o
5add in KOH solution, be conducive to Nb
2o
5fully dissolve in KOH solution, then carry out Hydrothermal Synthesis, contribute to KNbO by such feeding sequence
3the nucleation of crystal and growth.
In addition, the present inventor finds, because KOH very easily absorbs moisture in air and deliquescence, so when adopting KOH as raw material, inevitably containing the water of some, the water content of usual KOH is 5-10 % by weight, sometimes up to 30 % by weight.Water contained in KOH becomes the solvent in KOH solution the most at last, and change of moisture content in KOH raw material is larger, such as can change in 5-30 % by weight scope, the water comprised in KOH will cause the concentration of the KOH solution of the aimed concn of actual preparation to change in a relatively wide scope.Thus, be easy to cause there is difference (namely between the actual pH of solution and theoretical pH value, the actual pH of solution is less than theoretical pH value), this difference increases with the increase of the water content in KOH raw material, and the pH value of solution can by affecting the charging property of particle surface thus affecting the product types (i.e. the pattern of resultant and crystalline phase) of reaction system.Therefore, under further preferable case, by accurately controlling the concentration of potassium hydroxide aqueous solution, thus purity and the higher product of degree of crystallinity can be prepared.
Therefore, when configuring the KOH aqueous solution of a certain concentration, the first water content of clear and definite KOH reagent, then weigh in the amount of the KOH reagent of KOH butt, calculate the quality of the water in KOH reagent, and add the water yield required except the quality of the water in KOH reagent, the more accurate KOH aqueous solution of this concentration can be configured.
According to the present invention, under preferable case, to be that the KOH solid by being 5-30 % by weight is soluble in water by water content obtain the described KOH aqueous solution, water (water that described water comprises water contained in KOH solid and adds as required) and in the weight ratio of the KOH solid of butt for 0.95-1.52:1.Adopt the KOH aqueous solution of the concentration of this proportional arrangement, be conducive to obtaining purity and the better product of degree of crystallinity.
Owing to considering that KOH can contain the water of 5-30 % by weight usually; the KOH solution of its configuration is not only because the minimizing of solute but also the increase because of solvent can reduce the concentration of solution; and the pH value error usually adopting pH value meter or pH value tester to measure is comparatively large, so the usual also out of true of the pH value of the KOH solution obtained.The present inventor to consider in raw material KOH that when configuring KOH solution the contained water yield can become a part for solvent, can the more accurate KOH solution of configuration concentration, thus reaches ingredient proportion more accurately, obtains purity and the better product of degree of crystallinity.
According to the present invention, KOH and Nb
2o
5weight ratio those skilled in the art can select according to prior art, but if KOH is moisture, the existence of water not only can cause KOH solution concentration to reduce, and the actual KOH molar weight dropped into also can be caused to reduce.So, in order to better realize object of the present invention, at calculating K OH and Nb
2o
5consumption time, KOH needs in butt, if directly with the weighing scale of the KOH raw material containing water, then actual KOH and the Nb obtained
2o
5weight ratio will lower than KOH and the Nb of theory
2o
5weight ratio, such as, adopt water content be 10 % by weight KOH raw material and Nb
2o
5when the weight ratio calculating theoretical input amount is 25:1, when considering KOH feed moisture content, KOH input amount is 111g, Nb
2o
5input amount is that 4g just can reach KOH and Nb
2o
5weight ratio be 25:1; When not considering KOH feed moisture content, KOH input amount is 100g, Nb
2o
5input amount is 4g, its actual KOH and Nb
2o
5weight ratio be 22.5:1.When raw material KOH water content is higher, actual KOH and Nb
2o
5weight ratio will be larger with the gap of theoretical weight ratio.So, when considering that raw material KOH is moisture, preferably in KOH and the Nb of butt
2o
5mol ratio be 25-40:1, in order to obtain the KNbO of orthorhombic phase and Emission in Cubic
3crystal, further preferred KOH and Nb
2o
5mol ratio be 25-35:1.
It should be noted that, when in KOH and the Nb of butt
2o
5mol ratio when being 25-30:1, can purity be obtained high, particle agglomeration mild degree, the potassium niobate of the orthorhombic phase that crystallization degree is high; When in KOH and the Nb of butt
2o
5mol ratio when being 35:1, can purity be obtained high, narrow diameter distribution, particle agglomeration mild degree, the potassium niobate of the Emission in Cubic that crystallization degree is high.And work as in KOH and the Nb of butt
2o
5mol ratio be: be greater than 30 to being less than 35:1, and be in and be greater than 35 to when being less than or equal to 40:1, obtain orthorhombic phase phase potassium niobate.
According to the present invention, hydrothermal synthesis method is adopted to carry out the preparation of potassium niobate powder, the condition of carrying out Hydrothermal Synthesis can be selected according to prior art, but in order to better realize object of the present invention, under preferable case, the temperature of carrying out Hydrothermal Synthesis is 160-170 DEG C, and the time is 11-12 hour.The temperature of Hydrothermal Synthesis can be realized by the type of heating such as oil bath, baking oven.The present invention preferably adopts baking oven for heating, be heated evenly, be more conducive to synthesis purity high, the potassium niobate that degree of crystallinity is high.
Usually under the condition stirred, Hydrothermal Synthesis is carried out.The present invention preferably carries out Hydrothermal Synthesis under static conditions.Owing to present invention defines feeding sequence, be conducive to Nb
2o
5homogeneous phase mixing in KOH solution, so by Nb
2o
5join in the KOH aqueous solution, the solution mixed is carried out Hydrothermal Synthesis under static conditions, be conducive to obtaining purity and the better product of degree of crystallinity.
According to the present invention, the mode of the product of Hydrothermal Synthesis gained being carried out to solid-liquid separation can be carried out with reference to prior art, and such as filtration, centrifugation etc., the present invention preferably adopts centrifugation mode.
According to the present invention, under preferable case, the method is washed before being also included in and carrying out drying to the solid obtained.The object of described washing is removing foreign ion, and cleaning solvent used can be water and/or ethanol.Preferred employing water and ethanol wash the solid obtained respectively, and first wash with water, then use washing with alcohol, until the solution of washing is neutrality.
According to the present invention, the method for described drying is conventionally known to one of skill in the art, such as, seasoning, forced air drying, vacuum-drying etc., the present invention preferably adopts the method for forced air drying to carry out drying; Dry condition is not particularly limited, and the temperature of preferred described drying is 60-80 DEG C, and the time is 12-18 hour.
In the present invention, KOH butt weight is obtained by gravitational thermal analysis method measurement.
Present invention also offers a kind of potassium niobate powder prepared by aforesaid method.Compared with the potassium niobate powder prepared according to the conventional method, the grain diameter of described potassium niobate powder of the present invention is 500-1000nm, size distribution is narrower (as shown in Figure 5, the size distribution of 500-800nm reaches 67%), purity is higher, particle agglomeration degree is comparatively light, crystallization degree higher (by the analysis degree of crystallinity of XRD result more than 95%).
Below will be described the present invention by embodiment, but the present invention is not limited in following embodiment.
In following examples, TEM test adopts the TecnaiG2F20U-TWIN equipment of FEI Co. to carry out; SEM test adopts the HitachiS-4800 equipment of FEI Co. to carry out; XRD test adopts the XRD-6000 equipment of Shimadzu company to carry out; Degree of crystallinity is analyzed by XRD analysis software MDI-jade and is obtained; Size-grade distribution adopts methods analyst SEM photo being carried out to statistical study.
Following reagent is commercial goods unless stated otherwise.
Embodiment 1
Under room temperature (all referring to 25 DEG C in the present invention), in three neck round-bottomed flasks, add 26.92gKOH (water content 30 % by weight) and 20mL deionized water, be stirred to and dissolve completely, by 3.57gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
As shown in Figure 1, as shown in Figure 2, XRD spectra is as shown in Fig. 6 (a) for TEM photo for the SEM photo of gained potassium niobate product.
Potassium niobate particle agglomeration degree is lighter as can be seen from Figure 1; Be (001) and (110) face (by contrasting with PDF card, can find out that spacing corresponding to these two faces is consistent with the orthorhombic phase of potassium niobate) of orthorhombic phase potassium niobate as can be seen from Figure 2 in picture; Can find out that the potassium niobate obtained is orthorhombic phase from Fig. 6 (a), and inclusion-free peak in picture, illustrate that the potassium niobate purity obtained is higher, and degree of crystallinity reaches 97%.
Embodiment 2
At room temperature, in three neck round-bottomed flasks, add 37.69gKOH (water content 30 % by weight) and 17mL deionized water, be stirred to and dissolve completely, by 3.57gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
As shown in Figure 3, as shown in Figure 4, as shown in Figure 5, XRD spectra is as shown in Fig. 6 (b) for size distribution for TEM photo for the SEM photo of gained potassium niobate product.
The growth of potassium niobate particle crystalline form is complete as can be seen from Figure 3, size is comparatively even, reunion degree is lighter; Be (100) and (001) face (by contrasting with PDF card, can find out that spacing corresponding to these two faces is consistent with the Emission in Cubic of potassium niobate) of Emission in Cubic potassium niobate as can be seen from Figure 4 in picture; The potassium niobate sample particle diameter distribution range that can obtain as apparent from the grain size distribution of Fig. 5 is narrower, reaches 67% in the size distribution of 500-800nm; Can find out that the potassium niobate obtained is Emission in Cubic from Fig. 6 (b), and inclusion-free peak in picture, illustrate that the potassium niobate purity obtained is higher, and degree of crystallinity reaches 98%.
Embodiment 3
At room temperature, in three neck round-bottomed flasks, add 31.04gKOH (water content 15 % by weight) and 23.5mL deionized water, be stirred to and dissolve completely, by 3.57gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 80 DEG C dry 15 hours, obtain potassium niobate product.
The SEM photo of gained potassium niobate product is similar to Fig. 3, and TEM photo is similar to Fig. 4, and size distribution is close with Fig. 5, and XRD spectra is similar to Fig. 6 (b); The growth of particle crystalline form is complete, size is comparatively even, crystallization degree is high.
Embodiment 4
At room temperature, in three neck round-bottomed flasks, add 27.77gKOH (water content 5 % by weight) and 27mL deionized water, be stirred to and dissolve completely, by 3.57gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
The SEM photo of gained potassium niobate product is similar to Fig. 3, and TEM photo is similar to Fig. 4, and size distribution is close with Fig. 5, and XRD spectra is similar to Fig. 6 (b); The growth of particle crystalline form is complete, size is comparatively even, crystallization degree is high.
Embodiment 5
At room temperature, in three neck round-bottomed flasks, add 22.689gKOH (water content 30 % by weight) and 14mL deionized water, be stirred to and dissolve completely, by 2.5gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 170 DEG C, heats 11 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
The SEM photo of gained potassium niobate product is similar to Fig. 1, and TEM photo is similar to Fig. 2, and XRD spectra is similar to Fig. 6 (a); Crystallization degree is high.
Embodiment 6
At room temperature, in three neck round-bottomed flasks, add 30.15gKOH (water content 30 % by weight) and 15mL deionized water, be stirred to and dissolve completely, by 2.5gNb
2o
5join in the above-mentioned KOH aqueous solution, stir half an hour (mixing).It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then under static conditions, autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
As shown in Figure 7, XRD spectra as shown in Figure 8 for the SEM photo of gained potassium niobate product.
Potassium niobate particle agglomeration degree is lighter as can be seen from Figure 7; The potassium niobate obtained as can be seen from Figure 8 is orthorhombic phase, and inclusion-free peak in picture, illustrate that the potassium niobate purity obtained is higher, and degree of crystallinity is 95%.
Comparative example 1
At room temperature, in three neck round-bottomed flasks, 27mL deionized water and 3.57gNb is added
2o
5, add 27.77gKOH (water content 5 % by weight), stir half an hour.It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, sealing.Then autoclave being put into temperature is in the baking oven of 160 DEG C, heats 12 hours.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
As shown in Figure 9, XRD spectra as shown in Figure 10 for the SEM photo of gained potassium niobate product.
Gained potassium niobate particle crystalline form is grown incomplete more as can be seen from Figure 9, and shape size obvious difference, particle agglomeration degree is serious; The potassium niobate purity obtained as can be seen from Figure 10 is not high, and containing a lot of impurity peaks in figure, as there is impurity peaks the many places such as 12 °, 25 °, 39 °, and degree of crystallinity also reduces, and is 90%.
Comparative example 2
Potassium niobate powder is prepared according to the method for comparative example 1, unlike, when configuring the KOH solution of the concentration of comparative example 1, do not consider the water content of KOH, namely in three neck round-bottomed flasks, add 27mL deionized water and 3.57gNb
2o
5, add 25.1gKOH (theoretical concentration of KOH solution is 48.2 % by weight), the actual concentrations of KOH solution is 45.8 % by weight.
As shown in figure 11, XRD spectra as shown in figure 12 for the SEM photo of gained potassium niobate product.
Gained potassium niobate particle crystalline form is grown incomplete more as can be seen from Figure 11, and shape size obvious difference, particle agglomeration degree is serious; The potassium niobate degree of crystallinity obtained as can be seen from Figure 12 reduces, and is 87%.
Comparative example 3
At room temperature, in three neck round-bottomed flasks, 27mL deionized water and 3.57gNb is added
2o
5, add 25.1gKOH (not considering water content), stir half an hour.It is in the autoclave of 50mL that mixed solution in three neck round-bottomed flasks is transferred to volume, seals after putting into magnetic stir bar.Then put into by autoclave in the middle of the oil bath pan filling silicone oil, it is 160 DEG C that temperature controls, and heats 12 hours under agitation.After naturally cooling to room temperature, using water and ethanol (deionized water wash three times, washing with alcohol one time) to carry out eccentric cleaning to pH value of solution successively to the white product obtained is about 7, then in the baking oven of 60 DEG C dry 12 hours, obtain potassium niobate product.
As shown in figure 13, XRD spectra as shown in figure 14 for the SEM photo of gained potassium niobate product.
Gained particle crystalline form is grown incomplete more as can be seen from Figure 13, and shape size obvious difference, and should be unreacted Niobium Pentxoxide from the known most of particle of XRD analysis; The XRD peak of the potassium niobate obtained as can be seen from Figure 14 does not occur substantially, and the XRD peak in figure is more identical with the peak of commercial Niobium Pentxoxide, illustrates that reaction not exclusively.
More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.
It should be noted that in addition, each concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode, in order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible array mode.
In addition, also can carry out arbitrary combination between various different embodiment of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (4)
1. a preparation method for potassium niobate powder, is characterized in that, the method comprises Nb
2o
5join in the KOH aqueous solution, the solution mixed is carried out Hydrothermal Synthesis under static conditions, solid-liquid separation is carried out to the product of Hydrothermal Synthesis gained, and drying obtains solid; To be that the KOH solid by being 5-30 % by weight is soluble in water by water content obtain the described KOH aqueous solution, water with in the weight ratio of the KOH solid of butt for 0.95-1.52:1; In KOH and the Nb of butt
2o
5mol ratio be 25-40:1.
2. method according to claim 1, wherein, in KOH and the Nb of butt
2o
5mol ratio be 25-35:1.
3. method according to claim 1, wherein, the condition of carrying out Hydrothermal Synthesis comprises: temperature is 160-170 DEG C, and the time is 11-12 hour.
4. method according to claim 1, wherein, dry condition comprises: temperature is 60-80 DEG C, and the time is 12-18 hour.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101186339A (en) * | 2007-12-04 | 2008-05-28 | 北京科技大学 | Microwave hydro-thermal synthesis method for sodium niobate potassium niobate leadless piezoelectric ceramic powder |
| CN101249985A (en) * | 2008-03-25 | 2008-08-27 | 大连理工大学 | Controllable preparation method of orthorhombic-phase rhombohedral-phase sodium niobate having high Curie point |
| CN101575215A (en) * | 2009-06-10 | 2009-11-11 | 桂林理工大学 | Hydro-thermal synthesis method of potassium niobate powder |
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| CN101186339A (en) * | 2007-12-04 | 2008-05-28 | 北京科技大学 | Microwave hydro-thermal synthesis method for sodium niobate potassium niobate leadless piezoelectric ceramic powder |
| CN101249985A (en) * | 2008-03-25 | 2008-08-27 | 大连理工大学 | Controllable preparation method of orthorhombic-phase rhombohedral-phase sodium niobate having high Curie point |
| CN101575215A (en) * | 2009-06-10 | 2009-11-11 | 桂林理工大学 | Hydro-thermal synthesis method of potassium niobate powder |
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