CN115304369B - Preparation method of high-dielectric high-breakdown strontium titanate ceramic - Google Patents
Preparation method of high-dielectric high-breakdown strontium titanate ceramic Download PDFInfo
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Abstract
The application discloses a preparation method of high-dielectric high-breakdown strontium titanate ceramic, and belongs to the technical field of ceramic material preparation. The preparation method comprises the following steps: preparing a strontium titanate ceramic blank; heating the strontium titanate ceramic blank to 1000-1150 ℃ and preserving heat for 30min at the temperature of 1000-1150 ℃; applying a constant voltage electric field with the intensity of 250V/cm to two ends of the strontium titanate ceramic blank after heat preservation until flash burning occurs, and then controlling the current density to be increased to 10-30 mA/mm 2 And continuing to flash, and ending the flash after 30-120S to obtain the high-dielectric high-breakdown strontium titanate ceramic. The preparation method provided by the application obviously shortens the sintering time and reduces the sintering temperature by performing flash sintering of the technological parameters such as control voltage, current density and the like after preheating at a high temperature in a short time, and inhibits the grain growth of the ceramic under the condition of keeping high densification, thereby realizing the improvement of dielectric and breakdown characteristics of the strontium titanate ceramic.
Description
Technical Field
The application belongs to the technical field of ceramic material preparation, and particularly relates to a preparation method of high-dielectric high-breakdown strontium titanate ceramic.
Background
The ceramic dielectric capacitor is used as a common energy storage element in a pulse power system, has the advantages of high power density, high charge and discharge speed, long cycle life and the like, and can be widely applied to the fields of military weapons, aerospace, electric automobiles, medical equipment and the like. However, as electronic devices gradually enter the miniaturization and microminiaturization times, the energy storage density of dielectric materials is urgently required to be improved.
Strontium titanate ceramics, as a typical linear dielectric material, not only exhibit a paraelectric phase at room temperature, but also exhibit excellent electrical characteristics such as extremely low dielectric loss (< 1%), relatively high breakdown strength (> 200 kV/cm), and medium dielectric constant (-300), have been attracting attention in dielectric capacitor applications.
However, the existing preparation of strontium titanate ceramics generally needs to be carried out at high temperature (1350-1500 ℃) for a long time (more than 2 hours), and long-time high-temperature treatment can not only cause abnormal growth of crystal grains and seriously deteriorate the breakdown performance of the ceramics, thereby limiting the improvement of energy storage density, but also cause the problems of excessive energy consumption, aggravation of environmental pollution and the like due to relatively high energy consumption and time consumption in the whole preparation process.
Disclosure of Invention
The application aims to provide a preparation method of high dielectric high breakdown strontium titanate ceramic, which comprises the steps of heating a strontium titanate ceramic blank to 1000-1150 ℃ and preserving heat for 30min, applying a constant voltage electric field of 250V/cm until flash burning occurs, and then controlling the current density to be increased to 10-30 mA/mm 2 The continuous flash firing not only solves the technical problems of energy consumption and time consumption in the existing preparation of strontium titanate ceramics, but also solves the technical problem of abnormal growth of ceramic grains.
In order to achieve the above purpose, the present application adopts the following technical scheme:
the embodiment of the application provides a preparation method of high-dielectric high-breakdown strontium titanate ceramic, which comprises the following steps:
preparing a strontium titanate ceramic blank;
heating the strontium titanate ceramic blank to 1000-1150 ℃ and preserving heat for 30min at the temperature of 1000-1150 ℃;
applying a constant voltage electric field with the intensity of 250V/cm to two ends of the strontium titanate ceramic blank after heat preservation until flash burning occurs, and then controlling the current density to be increased to 10-30 mA/mm 2 And continuing to flash, and ending the flash after 30-120S to obtain the high-dielectric high-breakdown strontium titanate ceramic.
As a further improvement of the embodiment of the present application, the preparing a strontium titanate ceramic body includes:
preparing strontium titanate ceramic powder by taking strontium carbonate and titanium dioxide as raw materials;
and sequentially performing secondary ball milling, secondary drying, sieving and pressing on the strontium titanate ceramic powder to obtain a strontium titanate ceramic blank.
As a further improvement of the embodiment of the present application, the preparing a strontium titanate ceramic body further includes:
and (3) performing cold isostatic pressing treatment on the strontium titanate ceramic blank, wherein the pressure of the cold isostatic pressing is controlled to be 200Mpa, and the pressure maintaining time is 3min.
As a further improvement of the embodiment of the application, the preparation of the strontium titanate ceramic powder by taking strontium carbonate and titanium dioxide as raw materials comprises the following steps:
weighing strontium carbonate and titanium dioxide raw materials according to the stoichiometric ratio of strontium titanate, and then mixing and ball milling the strontium carbonate and titanium dioxide raw materials with zirconia ball stone and deionized water according to the mass ratio of 1:3:1 for 8-12 hours;
drying the ball-milled mixed raw materials at the temperature of 80 ℃, and then calcining for 2 hours at the temperature of 1200 ℃ to obtain the strontium titanate ceramic powder.
As a further improvement of the embodiment of the application, the time for performing secondary ball milling on the strontium titanate ceramic powder is 8-12 hours; the temperature of the secondary drying was 80 ℃.
As a further improvement of the embodiment of the application, the standard mesh number of sieving the strontium titanate ceramic powder is 120-200 meshes.
As a further improvement of the embodiment of the application, the heating rate of the strontium titanate ceramic body is 10 ℃/min.
As a further improvement of the embodiment of the application, the control current density is increased to 10-30 mA/mm 2 Completed in 1S.
As a further improvement of the embodiment of the application, the high dielectric high breakdown strontium titanate ceramic has a breakdown strength of 370kV/cm; the energy storage density is 2.21J/cm 3 。
As a further improvement of the embodiment of the application, the dielectric constant of the high-dielectric high-breakdown strontium titanate ceramic at 1kHz is 380, and the dielectric loss is 0.008.
One or more technical solutions provided in the embodiments of the present application have the following technical effects or advantages:
the preparation method of the high-dielectric high-breakdown strontium titanate ceramic provided by the embodiment of the application comprises the following steps ofHeating the porcelain blank to 1000-1150 ℃ and preserving heat for 30min, then applying a constant voltage electric field of 250V/cm until flash firing occurs, and then controlling the current density to be increased to 10-30 mA/mm 2 And continuing to flash for 30-120S to prepare the high-dielectric high-breakdown strontium titanate ceramic. In view of this, the embodiment of the application adopts the short-time high-temperature preheating and the joule heat under the action of the electric field to sinter the strontium titanate ceramic, the sintering time is obviously shortened, the energy and time saving in the preparation process is realized, the grain growth of the ceramic is inhibited under the condition of keeping high densification, and the improvement of the dielectric and breakdown characteristics of the strontium titanate ceramic is realized. In addition, the preparation method provided by the embodiment of the application has the advantages of simple equipment, high production efficiency, energy conservation and environmental protection, and can be widely applied to the industrial production of ceramic materials.
The performance test of the strontium titanate ceramic prepared by the embodiment of the application comprises the following steps: has a compact microstructure, no obvious air holes exist, the relative density reaches 97%, and the average grain size is 1.77 mu m; has good dielectric properties, dielectric constant epsilon=380 at 1kHz, dielectric loss tan delta=0.008, and the dielectric properties show excellent temperature and frequency stability; has more excellent breakdown strength and energy storage density, wherein the breakdown strength is 370kV/cm, and the energy storage density is 2.21J/cm 3 。
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments of the present application will be briefly described below. It will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the application and that other drawings may be derived from them without undue effort.
FIG. 1 is a graph of voltage strength and current density versus time for the preparation of strontium titanate ceramic in accordance with an embodiment of the present application;
FIG. 2 is a graph of power loss over time for a strontium titanate ceramic prepared in accordance with an embodiment of the present application;
FIG. 3 is an SEM image of a strontium titanate ceramic prepared according to an embodiment of the present application;
FIG. 4 is a graph of the grain size distribution of strontium titanate ceramic prepared in accordance with an embodiment of the present application;
FIG. 5 is a graph of dielectric properties of strontium titanate ceramics prepared in accordance with the examples of the present application as a function of frequency;
FIG. 6 is a graph of dielectric properties of strontium titanate ceramics prepared in accordance with the examples of the present application as a function of temperature;
FIG. 7 is a graph of the strontium titanate ceramic P-E loops prepared in accordance with the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the following description, the ball mill for performing ball milling was a QM-3SP2 planetary ball mill manufactured by Nanjin Instrument Co., ltd; the drying oven is a 101-AB electrothermal blowing drying oven manufactured by Tianjin Test instruments Co., ltd; the press for cold isostatic pressing is an LDJ100/320-300 type press manufactured by Chuan machine Limited liability company; the flash Power supply is a direct current Power supply with the model SL1250-1.2/UI manufactured by Magna-Power company of America, the voltage is adjustable within the range of 0-1250V, and the current is adjustable within the range of 0-1.2A.
The preparation method of the high-dielectric high-breakdown strontium titanate ceramic provided by the embodiment of the application comprises the steps S101 to S103.
S101: preparing a strontium titanate ceramic blank;
s102: heating the strontium titanate ceramic blank to 1000-1150 ℃ and preserving heat for 30min at the temperature of 1000-1150 ℃;
s103: applying a constant voltage electric field with the intensity of 250V/cm to two ends of the strontium titanate ceramic blank after heat preservation until flash burning occurs, and then controlling the current density to be increased to 10-30 mA/mm 2 And continue the flash firing, and finish the flash after 30-120SFiring to obtain the high dielectric high breakdown strontium titanate ceramic.
The preparation method of the high dielectric high breakdown strontium titanate ceramic provided by the embodiment of the application heats the strontium titanate ceramic blank to 1000-1150 ℃ and carries out heat preservation treatment for 30min, then the strontium titanate ceramic blank is subjected to flash firing by applying a constant voltage electric field of 250V/cm, and the current density is controlled to be increased to 10-30 mA/mm after the flash firing occurs 2 And continuing to flash for 30-120S to prepare the high-dielectric high-breakdown strontium titanate ceramic. In view of this, the embodiment of the application performs flash sintering of control of technological parameters such as voltage, current density, etc. after preheating at a high temperature in a short time, and in the first aspect, the sintering temperature of the strontium titanate ceramic is reduced from 1350-1500 ℃ to 1000-1150 ℃ and the whole sintering time is less than or equal to 2min, so that the sintering time is obviously shortened while the sintering temperature is reduced. Meanwhile, the flash sintering is a sintering mode of 'from inside to outside' by means of the Joule heat under the action of an electric field, and compared with the traditional 'from outside to inside' heat radiation sintering mode, the flash sintering can avoid excessive loss of heat, so that the heating efficiency is higher. The second aspect carries out flash sintering after preheating at a high temperature in a short time, and carries out effective control of technological parameters such as voltage, current density and the like in the flash sintering, so that not only can the grain growth of the strontium titanate ceramic be inhibited, but also the microstructure of the strontium titanate ceramic can be improved, thereby preparing the dielectric ceramic with high densification degree and fine grains, and realizing further improvement of the dielectric property and breakdown strength of the strontium titanate ceramic. According to the preparation method provided by the embodiment of the application, the traditional tube furnace or the muffle furnace is only required to be used for flash sintering, large-scale or complex professional equipment is not required, the preparation method has the advantage of simple process equipment, the whole preparation process is energy-saving and time-saving, the production efficiency is high, the energy is saved, and the environment is protected, so that the preparation method can be widely applied to the industrial production of ceramic materials.
It should be noted that, the strontium titanate ceramic body prepared in the embodiment of the application is preferably dog-bone-shaped, and in the embodiment of the application, holes are preferably drilled at two ends of the prepared dog-bone-shaped strontium titanate ceramic body, the dog-bone-shaped strontium titanate ceramic body is respectively hung on parallel platinum wires through the holes at two ends, and after the other end of the platinum wires is connected with a power supply, the dog-bone-shaped strontium titanate ceramic body and the platinum wires are integrally placed in a traditional tube furnace or a muffle furnace for flash sintering.
It should be noted that, the embodiment of the application researches the change relation of voltage intensity and current density with time in sintering of the dog-bone strontium titanate ceramic blank, and the results are shown in fig. 1-2. Wherein FIG. 1 is a graph of voltage intensity and current density versus time for an embodiment of the present application in the preparation of strontium titanate ceramic; FIG. 2 is a graph of power loss over time for a strontium titanate ceramic prepared in accordance with an embodiment of the present application.
As can be seen from FIGS. 1 and 2, the dog-bone strontium titanate ceramic body of the embodiment of the application is flash-burned quickly after a constant voltage electric field of 250V/cm is applied, and then the current density is controlled to be rapidly increased to 10-30 mA/mm 2 And simultaneously, the resistance of the sample is changed to a certain steady-state range, and an obvious power loss peak is generated at a flash burning occurrence point.
In an embodiment of the present application, the step of preparing a strontium titanate ceramic body preferably includes:
preparing strontium titanate ceramic powder by taking strontium carbonate and titanium dioxide as raw materials;
and sequentially performing secondary ball milling, secondary drying, sieving and pressing on the strontium titanate ceramic powder to obtain a strontium titanate ceramic blank.
The specific sources of the strontium carbonate and the titanium dioxide are not particularly specified in the embodiment of the present application, so as to obtain strontium titanate meeting the chemical composition requirements.
In an embodiment of the present application, the preparation of the strontium titanate ceramic body preferably further includes:
and (3) performing cold isostatic pressing treatment on the strontium titanate ceramic blank, wherein the pressure of the cold isostatic pressing is controlled to be 200Mpa, and the pressure maintaining time is 3min.
In the embodiment of the application, the preparation of the strontium titanate ceramic powder by taking the strontium carbonate and the titanium dioxide as raw materials preferably comprises the following steps:
weighing strontium carbonate and titanium dioxide raw materials according to the stoichiometric ratio of strontium titanate, and then mixing and ball milling the strontium carbonate and titanium dioxide raw materials with zirconia ball stone and deionized water according to the mass ratio of 1:3:1 for 8-12 hours;
drying the ball-milled mixed raw materials at the temperature of 80 ℃, and then calcining for 2 hours at the temperature of 1200 ℃ to obtain the strontium titanate ceramic powder.
In the embodiment of the application, when the strontium carbonate and the titanium dioxide raw materials are weighed, the strontium carbonate and the titanium dioxide are taken according to the amounts of the substances, and a proper amount of the ball milling auxiliary agent is added for mixing after the strontium carbonate and the titanium dioxide raw materials are weighed, wherein the specific components, sources and the amount of the ball milling auxiliary agent are not particularly limited, so that the ball milling quality and the ball milling efficiency of the strontium carbonate and the titanium dioxide can be improved.
In the embodiment of the application, the time for performing secondary ball milling on the strontium titanate ceramic powder is preferably 8-12 hours; the temperature of the secondary drying is preferably 80 ℃.
In the embodiment of the application, the standard mesh number of sieving the strontium titanate ceramic powder is preferably 120-200 meshes.
In the embodiment of the application, the heating rate of the strontium titanate ceramic blank is preferably 10 ℃/min.
In the embodiment of the application, the control current density is increased to 10-30 mA/mm 2 Preferably in 1S, so that the voltage intensity is converted into a certain steady-state range following the resistance of the strontium titanate ceramic powder and a more obvious power loss peak is generated at the flash-burning occurrence point.
In the embodiment of the application, the breakdown strength of the high-dielectric high-breakdown strontium titanate ceramic is preferably 370kV/cm; the energy storage density is preferably 2.21J/cm 3 。
In the embodiment of the application, the dielectric constant of the high-dielectric high-breakdown strontium titanate ceramic at 1kHz is preferably 380, and the dielectric loss is preferably 0.008.
Based on the above description, the preparation method of the high dielectric high breakdown strontium titanate ceramic provided by the embodiment of the application preferably comprises the following steps:
s101: and weighing strontium carbonate and titanium dioxide as raw materials according to the stoichiometric ratio of strontium titanate, mixing and ball milling the raw materials, zirconia ball stone and deionized water for 8-12 hours according to the mass ratio of 1:3:1, drying the mixed raw materials obtained by ball milling at the temperature of 80 ℃ in sequence, and calcining for 2 hours in a muffle furnace at the temperature of 1200 ℃ to obtain the strontium titanate ceramic powder.
S102: performing secondary ball milling on the strontium titanate ceramic powder obtained by calcining in the step S101, zirconia ball stone and deionized water according to the mass ratio of 1:3:1 for 8-12 h, and performing secondary drying at 80 ℃ to obtain dry powder; sieving the dry powder by adopting a sample separating sieve of 120-200 ℃ to obtain fine and uniform strontium titanate ceramic powder; weighing a proper amount of strontium titanate ceramic powder, adding the powder into a mold, and pressing to obtain a dog-bone-shaped strontium titanate ceramic blank; and (3) carrying out cold isostatic pressing treatment on the dog-bone-shaped strontium titanate ceramic blank under the condition that the pressure is 200Mpa, and maintaining the pressure for 3min.
S103: after drilling holes at two ends of the dog-bone-shaped strontium titanate ceramic body, hanging the dog-bone-shaped strontium titanate ceramic body on a parallel platinum wire through holes at two ends of the dog-bone-shaped strontium titanate ceramic body, connecting the other end of the parallel platinum wire with a power supply, and finally, integrally placing the dog-bone-shaped strontium titanate ceramic body in a tube furnace;
s104: heating up the tube furnace to 1000-1150 ℃ at 10 ℃/min, preserving heat for 30min at 1000-1150 ℃, then applying a constant electric field with voltage strength of 250V/cm until flash burning occurs, and controlling the current to be rapidly increased to 10-30 mA/mm 2 And (5) cutting off a power supply after maintaining the flash state for 30-120S, and performing flash sintering to obtain the high-breakdown high-dielectric strontium titanate ceramic.
The technical scheme of the application will be further elaborated in the following in conjunction with specific embodiments.
Example 1
The preparation method of the high dielectric high breakdown strontium titanate ceramic provided in the embodiment 1 comprises the following steps:
s101: weighing strontium carbonate and titanium dioxide as raw materials according to the stoichiometric ratio of strontium titanate, and then sending the raw materials, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for mixing and ball milling for 8 hours; and (3) drying the mixed raw materials obtained by ball milling in an oven at the temperature of 80 ℃, and then calcining in a muffle furnace at the temperature of 1200 ℃ for 2 hours to obtain the strontium titanate ceramic powder.
S102: feeding the strontium titanate ceramic powder obtained by calcining in the step S101, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for secondary ball milling for 8 hours, and placing the mixture at the temperature of 80 ℃ for secondary drying to obtain dry powder; sieving the dry powder by adopting a 200 sample separating sieve to obtain fine and uniform strontium titanate ceramic powder; weighing a proper amount of strontium titanate ceramic powder, adding the powder into a mold, and pressing to obtain a dog-bone-shaped strontium titanate ceramic blank; and carrying out cold isostatic pressing treatment on the dog-bone-shaped strontium titanate ceramic blank under the condition that the pressure is 200Mpa, and maintaining the pressure for 3min, wherein the size of the measuring part of the dog-bone-shaped strontium titanate ceramic blank is 20mm multiplied by 3mm multiplied by 2.26mm.
S103: after drilling holes at two ends of the dog-bone-shaped strontium titanate ceramic body, hanging the dog-bone-shaped strontium titanate ceramic body on a parallel platinum wire through holes at two ends of the dog-bone-shaped strontium titanate ceramic body, connecting the other end of the parallel platinum wire with a power supply, and finally, integrally placing the dog-bone-shaped strontium titanate ceramic body in a tube furnace;
s104: heating the tube furnace to 1150 ℃ at a speed of 10 ℃ per minute, preserving heat at 1150 ℃ for 30min, then applying a constant electric field with a voltage strength of 250V/cm until a flash phenomenon occurs, and controlling the current to be rapidly increased to 10mA/mm 2 And (5) cutting off the power supply after maintaining the flash state 120S, and performing flash sintering to obtain the high-breakdown high-dielectric strontium titanate ceramic.
Example 2
The preparation method of the high dielectric high breakdown strontium titanate ceramic provided in the embodiment 2 comprises the following steps:
s101: weighing strontium carbonate and titanium dioxide as raw materials according to the stoichiometric ratio of strontium titanate, and then sending the raw materials, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for mixing and ball milling for 12 hours; and (3) drying the mixed raw materials obtained by ball milling in an oven at the temperature of 80 ℃, and then calcining in a muffle furnace at the temperature of 1200 ℃ for 2 hours to obtain the strontium titanate ceramic powder.
S102: feeding the strontium titanate ceramic powder obtained by calcining in the step S101, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for secondary ball milling for 12 hours, and placing the mixture at the temperature of 80 ℃ for secondary drying to obtain dry powder; sieving the dry powder by adopting a 120-mesh sample separating sieve to obtain fine and uniform strontium titanate ceramic powder; weighing a proper amount of strontium titanate ceramic powder, adding the powder into a mold, and pressing to obtain a dog-bone-shaped strontium titanate ceramic blank; and carrying out cold isostatic pressing treatment on the dog-bone-shaped strontium titanate ceramic blank under the condition that the pressure is 200Mpa, and maintaining the pressure for 3min, wherein the size of the measuring part of the dog-bone-shaped strontium titanate ceramic blank is 20mm multiplied by 3mm multiplied by 2.26mm.
S103: after drilling holes at two ends of the dog-bone-shaped strontium titanate ceramic body, hanging the dog-bone-shaped strontium titanate ceramic body on a parallel platinum wire through holes at two ends of the dog-bone-shaped strontium titanate ceramic body, connecting the other end of the parallel platinum wire with a power supply, and finally, integrally placing the dog-bone-shaped strontium titanate ceramic body in a tube furnace;
s104: heating the tube furnace to 1050 ℃ at 10 ℃/min, preserving heat at 1050 ℃ for 30min, then applying a constant electric field with voltage strength of 250V/cm until a flash phenomenon occurs, and controlling the current to be rapidly increased to 20mA/mm 2 And (5) cutting off the power supply after maintaining the flash state for 60S, and performing flash sintering to obtain the high-breakdown high-dielectric strontium titanate ceramic.
Example 3
The preparation method of the high dielectric high breakdown strontium titanate ceramic provided in the embodiment 2 comprises the following steps:
s101: weighing strontium carbonate and titanium dioxide as raw materials according to the stoichiometric ratio of strontium titanate, and then sending the raw materials, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for mixing and ball milling for 12 hours; and (3) drying the mixed raw materials obtained by ball milling in an oven at the temperature of 80 ℃, and then calcining in a muffle furnace at the temperature of 1200 ℃ for 2 hours to obtain the strontium titanate ceramic powder.
S102: feeding the strontium titanate ceramic powder obtained by calcining in the step S101, zirconia ball stone and deionized water into a ball mill according to the mass ratio of 1:3:1 for secondary ball milling for 12 hours, and placing the mixture at the temperature of 80 ℃ for secondary drying to obtain dry powder; sieving the dry powder by adopting a sample separating sieve of 120 to obtain fine and uniform strontium titanate ceramic powder; weighing a proper amount of strontium titanate ceramic powder, adding the powder into a mold, and pressing to obtain a dog-bone-shaped strontium titanate ceramic blank; and carrying out cold isostatic pressing treatment on the dog-bone-shaped strontium titanate ceramic blank under the condition that the pressure is 200Mpa, and maintaining the pressure for 3min, wherein the size of the measuring part of the dog-bone-shaped strontium titanate ceramic blank is 20mm multiplied by 3mm multiplied by 2.26mm.
S103: after drilling holes at two ends of the dog-bone-shaped strontium titanate ceramic body, hanging the dog-bone-shaped strontium titanate ceramic body on a parallel platinum wire through holes at two ends of the dog-bone-shaped strontium titanate ceramic body, connecting the other end of the parallel platinum wire with a power supply, and finally, integrally placing the dog-bone-shaped strontium titanate ceramic body in a tube furnace;
s104: heating the tube furnace to 1100 ℃ at 10 ℃/min, preserving heat at 1100 ℃ for 30min, then applying a constant electric field with the voltage strength of 250V/cm until the flash burning phenomenon occurs, and controlling the current to be rapidly increased to 30mA/mm 2 And after maintaining the flash state for 30S, cutting off the power supply, and performing flash sintering to obtain the high-breakdown high-dielectric strontium titanate ceramic.
The high-breakdown high-dielectric strontium titanate ceramic prepared in example 3 was subjected to performance characterization, and the results are shown in detail in fig. 3 to 7. Wherein, FIG. 3 is an SEM image of the strontium titanate ceramic prepared in example 3; FIG. 4 is a graph of the grain size distribution of the strontium titanate ceramic prepared in example 3; FIG. 5 is a graph of dielectric properties of the strontium titanate ceramic prepared in example 3 as a function of frequency; FIG. 6 is a graph of dielectric properties of the strontium titanate ceramic prepared in example 3 as a function of temperature; FIG. 7 is a P-E loops of the strontium titanate ceramic prepared in example 3.
As can be seen from fig. 3 to 4, the strontium titanate ceramic prepared in example 3 has a dense microstructure, no obvious pores exist, a relative density of 97%, an average grain size of 1.77 μm, and grain growth thereof is suppressed compared with the conventional sintering method.
As can be seen from fig. 5 to 6, the strontium titanate ceramic prepared in example 3 has good dielectric properties, a dielectric constant epsilon=380 at 1kHz, a dielectric loss tan δ=0.008, and excellent temperature and frequency stability.
As can be seen from FIG. 7, the titanium prepared in example 3The strontium titanate ceramics have a linear increasing trend of P-Eloops along with the continuous increase of an electric field, and the breakdown strength and the polarization strength are continuously increased, and the breakdown strength and the energy storage density of the strontium titanate ceramics prepared by the embodiment of the application are respectively up to 370kV/cm and 2.21J/cm 3 Whereas the breakdown and energy storage densities reported in the literature are 210kV/cm and 0.7J/cm 3 . Therefore, the preparation method provided by the embodiment of the application can obviously improve the breakdown strength and the energy storage density of the strontium titanate ceramic, wherein the breakdown strength of the strontium titanate ceramic is improved by 76.19% in a same way, and the energy storage density is improved by 215.71% in a same way.
The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances. In this specification, each embodiment is described in a progressive manner, and the same or similar parts of each embodiment are referred to each other, and each embodiment is mainly described as a difference from other embodiments.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the present application; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; such modifications and substitutions do not depart from the spirit of the application.
Claims (3)
1. The preparation method of the high dielectric high breakdown strontium titanate ceramic is characterized by comprising the following steps:
preparing a strontium titanate ceramic blank;
heating the strontium titanate ceramic blank to 1100 ℃, and preserving heat at 1100 ℃ for 30min;
applying a constant voltage electric field with the intensity of 250V/cm to two ends of the insulated strontium titanate ceramic blank until flash burning occurs, and then controlling the current density to be increased to 30mA/mm 2 And continuing to flash, and ending the flash after 30S to obtain the high-dielectric high-breakdown strontium titanate ceramic;
the preparation of the strontium titanate ceramic blank comprises the following steps:
preparing strontium titanate ceramic powder by taking strontium carbonate and titanium dioxide as raw materials;
sequentially performing secondary ball milling, secondary drying, sieving and pressing on the strontium titanate ceramic powder to obtain a strontium titanate ceramic blank;
the preparation of the strontium titanate ceramic body further comprises:
performing cold isostatic pressing treatment on the strontium titanate ceramic blank, wherein the pressure of the cold isostatic pressing is controlled to be 200Mpa, and the pressure maintaining time is 3min;
the preparation of the strontium titanate ceramic powder by taking strontium carbonate and titanium dioxide as raw materials comprises the following steps:
weighing strontium carbonate and titanium dioxide raw materials according to the stoichiometric ratio of strontium titanate, and then mixing and ball-milling the strontium carbonate and titanium dioxide raw materials with zirconia ball stone and deionized water according to the mass ratio of 1:3:1 for 12 hours;
drying the ball-milled mixed raw materials at the temperature of 80 ℃, and then calcining for 2 hours at the temperature of 1200 ℃ to obtain strontium titanate ceramic powder;
performing secondary ball milling on the strontium titanate ceramic powder for 12 hours; the temperature of the secondary drying is 80 ℃;
sieving the strontium titanate ceramic powder with a standard mesh number of 120 meshes;
the heating rate of the strontium titanate ceramic body is 10 ℃/min.
2. The method for producing a high dielectric high breakdown strontium titanate ceramic according to claim 1, wherein the high dielectric high breakdown strontium titanate ceramic has a breakdown strength of 370kV/cm; the energy storage density is 2.21J/cm 3 。
3. The method for producing a high dielectric high breakdown strontium titanate ceramic according to claim 1, wherein the high dielectric high breakdown strontium titanate ceramic has a dielectric constant of 380 at 1kHz and a dielectric loss of 0.008.
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| CN103708817A (en) * | 2013-12-19 | 2014-04-09 | 桂林电子科技大学 | High pressure-resistance leadless high-temperature ferroelectric ceramic and preparation method thereof |
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| US9334194B2 (en) * | 2011-07-29 | 2016-05-10 | The Regents Of The University Of Colorado, A Body Corporate | Methods of flash sintering |
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| CN103708817A (en) * | 2013-12-19 | 2014-04-09 | 桂林电子科技大学 | High pressure-resistance leadless high-temperature ferroelectric ceramic and preparation method thereof |
| CN109081691A (en) * | 2018-09-13 | 2018-12-25 | 长安大学 | A kind of tubular ceramic preparation method |
| CN111981847A (en) * | 2020-07-24 | 2020-11-24 | 北京科技大学 | Pressure-assisted induction heating vacuum atmosphere flash sintering device |
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