Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a niobate-based energy storage glass ceramic material with a compact boron-added glass structure and a preparation method thereof.
In order to realize the purpose, the technical scheme adopted by the glass ceramic is as follows:
the crystal phase is formed by K with a molar ratio of 7:1:82CO3、Na2CO3And Nb2O5(ii) a The glass phase is formed by mol ratio ofx:(1-x) SiO of (2)2、H3BO3(ii) a The molar ratio of the crystal phase to the glass phase is 4: the formula 1 is prepared by mixing, melting, molding, annealing and crystallizing.
The preparation method of the glass ceramic material adopts the technical scheme that the preparation method comprises the following steps:
1) k according to a 4 molar ratio of 7:1:82CO3、Na2CO3And Nb2O5(ii) a The glass phase is formed by SiO with a molar ratio of 1:32、H3BO3(ii) a The molar ratio of the crystal phase to the glass phase is 4:1 and mixing;
2) adding the mixture obtained in the step 1) into a quartz crucible and heating until a uniformly mixed melt is formed; pouring the melt into a mold for molding to obtain a glass sample, and annealing the glass sample;
3) the glass sample after annealing treatment is crystallizedThe crystallization treatment is heat preservation at 950 ℃ for 2 hours to obtain K2O-Na2O-Nb2O5-SiO2-B2O3The system is made of glass ceramic material.
Further, the heating temperature in the step 2) is 1450-1500 ℃.
Further, the annealing treatment in the step 2) is heat preservation for 8-11 hours at 500-600 ℃.
Further, the crystallization temperature of the glass sample in the step 3) is about 950 ℃.
Further, the devitrification temperature in step 3) is determined by DSC differential thermal analysis of the glass substrate sample.
Compared with the prior art, the invention has the beneficial effects that:
the potassium-sodium niobate glass ceramic material prepared by the invention has extremely low porosity, and simultaneously, three parts of a network forming body, a network outer body and a network intermediate are required for forming glass. B is2O3The glass network forming body has a more compact structure when it has an octahedral structure. Therefore, the invention reasonably controls B2O3The content ratio of the components can generate a compact network structure, the dielectric constant can reach 180, the breakdown field strength can reach 460kV/cm, the dielectric loss can be reduced to 0.073, the energy storage density is increased to 1.64J/cm3. In addition, NaNbO is formed in multiple forms during the preparation process3Phase example more addition of Na2CO3Therefore, these examples can also obtain more crystal phases.
The preparation method of the invention only needs to carry out mixing melting, molding, annealing and crystallization treatment on all raw materials to obtain the potassium-sodium niobate glass ceramic material.
Detailed Description
The method comprises the following specific steps:
1) k in a molar ratio of 7:1:82CO3、Na2CO3And Nb2O5(ii) a The glass phase is formed by mol ratio ofx:(1-x) SiO of (2)2、H3BO3(ii) a The molar ratio of the crystal phase to the glass phase is 4:1 and mixing to obtain a mixture;
2) heating a quartz crucible to 1000-1200 ℃ along with a furnace from room temperature, starting adding the mixture, then continuously heating to 1450-1500 ℃, and preserving heat for 50-60 min to ensure that the mixture is fully melted and has no bubbles to finally obtain a mixed molten material; molding the mixed molten material on a copper plate mold at room temperature, and quickly putting the copper plate mold into a furnace to anneal for 8-11 hours at 500-600 ℃ so as to eliminate internal stress and obtain a glass sample;
preserving the temperature of the glass sample at 950 ℃, performing segmented crystallization treatment for 4 hours, and cooling to room temperature along with the furnace to obtain K2O-Na2O-Nb2O5-SiO2-B2O3The system is made of glass ceramic material.
The present invention is further illustrated in detail below with reference to specific examples:
example 1:
crystallization treatment of the glass sample in this example: the temperature is kept at 950 ℃ for 4 h.
The preparation method of the glass ceramic material comprises the following steps:
1) k in the molar ratio of 7:1:8 in this example2CO3、Na2CO3And Nb2O5(ii) a The glass phase is formed by SiO with the mol ratio of 1:02、H3BO3(ii) a The molar ratio of the crystal phase to the glass phase is 4:1 and mixing.
2) Heating a quartz crucible along with a furnace from room temperature to 1100 ℃, starting adding the mixture, then continuing heating to 1500 ℃, and preserving heat at 1500 ℃ for 60min to uniformly melt the mixture to obtain a mixed molten material; molding the mixed molten material on a copper plate, and quickly putting the copper plate into a furnace to anneal for 11 hours at 500 ℃ to obtain an annealed glass substrate;
3) keeping the temperature at 950 ℃ for 4h, and then cooling the mixture to room temperature along with the furnace to obtain K2O-Na2O-Nb2O5-SiO2-B2O3The system is made of glass ceramic material.
Cutting the potassium-sodium niobate glass ceramic obtained in the embodiment into a sheet with the thickness of 0.1-0.2 mm by using a cutting machine, polishing and cleaning the sheet, uniformly coating silver electrode slurry on the front surface and the back surface of the sheet, and preserving heat at 600 ℃ for 20 minutes to obtain a glass ceramic sample to be detected.
Example 2:
the glass phase of the glass sample in this example is prepared by mixing the following components in a molar ratio of 0.85: 0.15 SiO2、H3BO3And the mixture was melted by feeding at 1500 ℃ and heat-preserved for 60min, under the same conditions as in example 1.
Example 3:
the formulation of the glass sample in this example was 0.7: 0.3 SiO2、H3BO3The other conditions were the same as in example 1.
Example 4:
the formulation of the glass sample in this example was 0.54: 0.46 SiO2、H3BO3The other conditions were the same as in example 1.
Example 5:
the formulation of the glass sample in this example was 0.37: 0.63 SiO2、H3BO3The other conditions were the same as in example 1.
Example 6:
the formulation of the glass sample in this example was 0: 1 SiO2、H3BO3The other conditions were the same as in example 1.
FIG. 1 is an X-ray diffraction analysis of the above six examples, showing the effect of different experimental formulations on their degree of crystallinity and phase. Can be seen at 950oAt the crystallization temperature of C, the crystallization degree of 6 examples is high, and the crystal phase is mainly NaNbO3。
FIG. 2 shows the dielectric property test results of the first glass-ceramic material prepared by the above six examples, which are as follows:
TABLE Performance test data for the glass-ceramic samples prepared in examples 1 to 4
Examples
|
1
|
2
|
3
|
4
|
5
|
6
|
Dielectric constant
|
150
|
75
|
100
|
73
|
70
|
72
|
Breakdown field strength (kV/cm)
|
425
|
460
|
400
|
415
|
375
|
350
|
Dielectric loss
|
0.060
|
0.074
|
0.045
|
0.027
|
0.025
|
0.028
|
Energy storage Density (J/cm)3)
|
1.34
|
1.43
|
1.18
|
1.05
|
0.89
|
0.73 |
According to the energy storage formula:
the breakdown field intensity is one of the most obvious factors influencing the energy storage density, and the glass ceramic material has reduced dielectric constant and increased breakdown field intensity due to the existence of glass, so the invention generates the ferroelectric glass ceramic with high dielectric constant, high breakdown field intensity and low dielectric loss by reasonably controlling the content of the antiferroelectric sodium niobate crystal. And the sample is prepared by adopting a melting method, the process is simple and convenient, the forming method is more, the breakdown strength is high, and the method is an important method for preparing the material with high energy storage density. The prepared potassium-sodium niobate glass ceramic with high dielectric constant and high breakdown field strength is expected to replace the traditional ferroelectric ceramic materialBecomes one of important candidate materials of the energy storage material with excellent technical and economic aspects.
The invention adopts the melting method to prepare the potassium-sodium niobate glass ceramic material, and has the advantages of simple and convenient preparation method, simple process flow, randomly controlled molding according to the requirement, short production period and particular suitability for industrial production. The crystallization treatment adopts the heat preservation time of 4 hours so that the crystal phase grows more completely and the crystallization is more thorough, and the crystal phase can be obtained through later test, and when the heat preservation treatment is carried out at a higher crystallization peak, the content of the internal crystal phase of the obtained potassium sodium niobate-based glass ceramic sample is higher, and the energy storage density is higher. The potassium-sodium niobate-based glass ceramic material prepared by the invention is a ferroelectric glass ceramic with high dielectric constant, high breakdown field strength and low dielectric loss.
The above description is only one embodiment of the present invention, and not all or only one embodiment, and any equivalent alterations to the technical solutions of the present invention, which are made by those skilled in the art through reading the present specification, are covered by the claims of the present invention.