A kind of ZnO/Bi
2o
3the preparation method of composite granule
Technical field
The present invention relates to a kind of ZnO/Bi
2o
3the preparation method of composite nano materials, more precisely, the present invention relates to a kind of ZnO/Bi of nucleocapsid structure of being got everything ready by in-stiu coating legal system
2o
3the method of nano-powder, belongs to composite nano powder preparing technical field.
Background technology
ZnO is a kind of II-VI group broad-band gap direct band gap wide bandgap semiconductor compound-material, and under its room temperature, forbidden band is wide is 3.37eV, has n-type semiconductor conductive characteristic, and be hexagonal wurtzite crystalline structure, crystal formation belongs to hexagonal system.ZnO nano material yardstick is little, surface-area is huge, and stable performance, photoelectric response characteristic are given prominence to, and has ultrafast time effect, so ZnO is widely used in construct detector, photovoltaic art, degradable organic pollutant etc.; The pressure-sensitive electronic ceramics of ZnO is matrix with ZnO and a class new function material of other metal ions (Bi, Mn, Co, Sb, Gr etc.) that adulterate, and in the production of zinc oxide pressure-sensitive ceramic, adds the larger low price ion of radius (as Bi
2o
3), formed by principal mode insulation layer, in sintering process, segregation is in crystal boundary, makes bill of material reveal good pressure-sensitive character.
The preparation method of current zinc oxide pressure-sensitive composite granule is mainly divided into two large classes: solid phase mechanical attrition method and liquid chemical method; Core-shell nano composite particles prepared by the employing high-energy ball milling method doping metals particle that Wang Wei etc. report, but obtained composite granule pattern is fuzzy, particle size is large, and churning time is long, although solid phase mechanical attrition method is simple to operate and cost is lower, but product purity is low, size distribution is uneven; The Surface coating of powder adopts physics or chemical process to process particle surface exactly, change the physics of particle surface, chemical property consciously, designed by surface coating technology and prepare the nano zine oxide of nucleocapsid structure, and then improve sintering and the microtexture performance of voltage-sensitive ceramic, significant to the application of accelerating oxidation zinc nano-powder on electronic ceramics; Realize coated nano particle performance with mechanical attrition method to be improved, but the bonding force of its nucleocapsid structure is not strong, covered effect is not fine.
Traditional surface cladding tech is first dissolved in distilled water by zinc salt, then add precipitation agent heated and stirred, is precipitated thing, then throw out filtration, washing, drying and calcining are obtained ZnO core; Then by ZnO powder and the mixing of bismuth salt, add applicable solvent, be obtained by reacting throw out, then by throw out filtration, washing, oven dry, calcining obtain the ZnO/Bi of nucleocapsid structure
2o
3composite nano powder, due to links such as the repeated drying in particulate production and roastings, carry out the dispersion that coated particle is often difficult to obtain, therefore covered effect is restricted; The present invention proposes a kind of new cladding process---in-stiu coating, react by certain density zinc nitrate solution and ammonium bicarbonate soln, obtain the precursor of ZnO------zinc subcarbonate, slurries are dispersed into further again by after zinc subcarbonate filtration washing, add ammonium bicarbonate soln and continue reaction, slowly add bismuth nitrate solution after for some time, question response carries out completely, bismuth throw out is made to be coated on zinc throw out surface completely, the ZnO/Bi of the nucleocapsid structure finally simultaneously formed
2o
3nano-powder, this technique not only eliminates multiple oven dry and roasting link, the more important thing is and can realize coated uniformly by the state controlling precursor, and improve the compactness that coating layer is combined with matrix; By the ZnO/Bi that this technique is obtained
2o
3composite granule uniform particles, particle size is less, and after sintering, ZnO voltage-sensitive ceramic compactness is high, and in-stiu coating method energy consumption in implementation process is lower, and products collection efficiency is higher, thing is uniformly dispersed mutually, can avoid the agglomeration traits produced because of high temperature sintering.
Summary of the invention
The present invention adopts in-stiu coating legal system for Bi
2o
3nano powder surface clading ZnO, obtained Bi
2o
3coated ZnO composite nano powder and composite ceramics.Found that through Bi
2o
3coated ZnO composite nano powder particle microstructure is even, and composite ceramics has higher compactness, and the present invention is achieved through the following technical solutions.
1, a kind of making ZnO-Bi
2o
3the method of composite nano powder, its concrete steps are as follows:
(1) with analytically pure Zn (NO
3)
26H
2o, Bi (NO
3)
25H
2o and NH
4hCO
3for raw material, calculate with molar content, according to the ZnO of 99%, the Bi of 1%
2o
3proportioning, configure Zn (NO respectively
3)
2, Bi (NO
3)
2, NH
4hCO
3the aqueous solution.
(2) by Zn (NO obtained for step (1)
3)
2the aqueous solution and NH
4hCO
3the aqueous solution stoichiometrically mixes, and keeps temperature of reaction 50 DEG C, stirs 30 min.
(3) by the white precipitate suction filtration of step (2) gained, and fully wash removal impurity with deionized water and ethanol, then disperse further in deionized water filtering the zinc subcarbonate obtained, form dispersion slurries.
(4) with analytically pure NH
4hCO
3for raw material, again prepare NH
4hCO
3the aqueous solution.
(5) ammonium bicarbonate soln that step (4) is obtained is stoichiometrically added the dispersion slurries that step (3) obtains, continuous stirring, and make system remain on 50 DEG C, then slowly add Bi (NO prepared by step (1)
3)
2the aqueous solution, makes the ZnO meeting 99%, the Bi of 1%
2o
3proportioning, continue stirring 30 min, make reaction carry out completely, make bismuth throw out be coated on the throw out of zinc completely surperficial.Finally the composite precipitation thing obtained filtered, wash, dry, calcining after grinding, the zinc oxide compound nano powder of acquisition Surface coating bismuth oxide.
Zn (the NO of preparation in described step 1
3)
2, Bi (NO
3)
2, NH
4hCO
3concentration of aqueous solution is 0.1mol/L.
In described step 3, zinc subcarbonate dispersion pulp fluid solid content is 10%.
The NH of preparation in described step 4
4hCO
3concentration of aqueous solution is 0.1mol/L.
Calcining in described step 5 refers to calcine 2h at 500 DEG C.
2, the preparation of ZnO pottery
(1) prepare massfraction be 5% polyvinyl alcohol water solution be added drop-wise in nano combined ZnO powder, grind in mortar, with 200 object sieve granulations, under 20MPa, be pressed into sheet.
(2) sintered at 1100 DEG C by the sheet biscuit that step (1) is obtained, under air atmosphere, be incubated 2h, temperature rate 2 DEG C/min, obtains ZnO voltage-sensitive ceramic.
(3) by the ZnO voltage-sensitive ceramic surface finish that step (2) is obtained, polishing, silver-colored, make electrode.
Material prescription provided by the invention and the nano combined ZnO powder obtained by preparation method are faint yellow, and particle diameter is 20 ~ 30nm; ZnO voltage-sensitive ceramic sheet is dark yellow solid, shrinking percentage 4% ~ 12%, pressure sensitive voltage V
1mAbe 120 ~ 260V/mm, leakage current J
leakbe 26 ~ 30 μ A(0.83V
1mA), nonlinear factor α is 4.9 ~ 11.5; Because potential gradient is relatively high, may be used for the overvoltage protection product etc. manufacturing high pressure, extra-high voltage Force system.
The present invention adopts the advantage of technique scheme to be:
(1) in-stiu coating method adopts that low temperature controls 50 ~ 60 DEG C of liquid phases, energy consumption is lower; Raw material is easy to get, with low cost;
(2) nano combined ZnO powder preparation technology is comparatively simple, carries out in-stiu coating, directly synthesizes, eliminate multiple oven dry and roasting link at the precursor of ZnO------basic carbonate zinc surface, realizes coated uniformly by the state controlling precursor.And energy consumption is lower, products collection efficiency is higher, thing is uniformly dispersed mutually, can avoid the agglomeration traits produced because of high temperature sintering.
Accompanying drawing explanation
?fig. 1 is the TEM figure of nano combined ZnO powder obtained by the present invention, and as can be seen from the figure nano ZnO powder granular size is 10-20nm, and pattern is homogeneous.
Fig. 2 is the infrared spectrogram of powder in the embodiment of the present invention 1,2,3,4, as seen from Figure 2, at 3444.71cm
-1peak be the stretching vibration peak of O-H, at 1633.43 cm
-1peak corresponding be absorb the flexural vibration of water.At 1383.17 cm
-1the peak observed is the stretching vibration of Zn-O key.At 480.59 cm
-1appearance strong peak, the stretch mode of corresponding is Bi-O key, infrared spectrum analytic explanation, bismuth oxide is evenly coated on nano granular of zinc oxide surface.
Fig. 3 is the relative density figure of pressure sensitive in the embodiment of the present invention 1,2,3,4, as can be seen from the figure ZnO/Bi
2o
3voltage-sensitive ceramic has high compactness.
Embodiment
Below in conjunction with drawings and Examples, the present invention will be further described, but never limit the scope of the invention:
Embodiment 1
1, ZnO/Bi
2o
3the preparation of powder
(1) taking the bicarbonate of ammonia of 7.8175g and 14.7130g zinc nitrate, to make concentration be respectively the 0.1 mol/L aqueous solution.
(2) zinc nitrate solution that step (1) is obtained is added in ammonium bicarbonate soln, constantly stir, keep temperature of reaction at 50 DEG C, after question response carries out 30min, obtain the zinc subcarbonate throw out (zinc carbonate) of white.
(3) by the precipitation suction filtration of step (2) gained, weighing filtering the zinc subcarbonate obtained (5.1413g), adding 51.4130g distilled water and disperseing further, forming dispersion slurries (solid content 10%)
(4) take 11.7328g bicarbonate of ammonia, 0.4836g Bismuth trinitrate makes the 0.1 mol/L aqueous solution respectively.
(5) ammonium bicarbonate soln that step (4) is obtained is added in the obtained slurries of step (3), continuous stirring, and make system remain on 50 DEG C, then the bismuth nitrate solution that step (4) is obtained is slowly added, continue to stir 30min, make reaction carry out completely, make bismuth throw out be coated on the throw out surface of zinc completely.
(6) finally the composite precipitation thing that step (5) obtains is filtered, washs, dried.At 500 DEG C of calcination 2h after pulverizing, obtain the zinc oxide compound nano powder of Surface coating bismuth oxide
2, ZnO/Bi
2o
3the preparation of pottery
(1) at ZnO/Bi
2o
3add the polyvinyl alcohol water solution that massfraction is 5% in composite granule, be ground to half-dried in mortar, with 200 object sieve granulations, tabletted under 20MPa;
(2) sintered at 1100 DEG C by the sheet biscuit that step (1) is obtained, under air atmosphere, be incubated 2h, temperature rate 2 DEG C/min, obtains ZnO/Bi
2o
3voltage-sensitive ceramic.
(3) by ZnO/Bi obtained for step (2)
2o
3voltage-sensitive ceramic surface finish, polishing, silver-colored, make electrode.
Embodiment 2
In the present embodiment, in-stiu coating legal system is for ZnO/Bi
2o
3during powder, take 1.4553g Bismuth trinitrate, calculate with molar content, make the ZnO meeting 97%, the Bi of 3%
2o
3proportioning; All the other each composition weight in the same manner as in Example 1; Above-mentioned materials adopts the processing step identical with embodiment 1, is prepared into ZnO voltage-sensitive ceramic.
Embodiment 3
In the present embodiment, in-stiu coating legal system is for ZnO/Bi
2o
3during powder, take 2.4255g Bismuth trinitrate, calculate with molar content, make the ZnO meeting 95%, the Bi of 5%
2o
3proportioning; All the other each composition weight in the same manner as in Example 1; Above-mentioned materials adopts the processing step identical with embodiment 1, is prepared into ZnO voltage-sensitive ceramic.
Embodiment 4
In the present embodiment, in-stiu coating legal system is for ZnO/Bi
2o
3during powder, take 3.3957g Bismuth trinitrate, calculate with molar content, make the ZnO meeting 93%, the Bi of 7%
2o
3proportioning; All the other each composition weight in the same manner as in Example 1; Above-mentioned materials adopts the processing step identical with embodiment 1, is prepared into ZnO voltage-sensitive ceramic.