CN111892093B - Microwave absorbing material and preparation method thereof - Google Patents
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Abstract
The invention provides a microwave absorbing material, the molecular formula of which is Bi (0～0.3) La (0.7～1) FeO 3 . Book (I)The microwave absorbing material provided by the invention has multiple polarizations, including space charge polarization, dipole polarization and interface polarization, so that the dielectric loss of the material is reduced, meanwhile, a large number of irregular micropores are formed in the material, the pore size distribution is narrow, multiple reflection channels exist, when electromagnetic waves are emitted into the material, the electromagnetic waves are reflected and scattered for multiple times in the material, so that the electromagnetic waves are attenuated more, and the purpose of reducing the thickness of the material and realizing excellent wave absorption performance is achieved. Experimental results show that the microwave absorbing material provided by the invention can absorb electromagnetic waves in a 2-18 GHz microwave band, the absorption efficiency is more than 90%, and the microwave absorbing material can obtain excellent microwave absorbing performance within the thickness of 1.6-2.0 mm.
Description
Technical Field
The invention relates to the technical field of materials, in particular to a microwave absorbing material and a preparation method thereof.
Background
With the development of communication technology, 5G technology will be a trend of development. When a 5G signal base station is constructed, high-frequency electromagnetic equipment has large energy output during working, the formed high-frequency electromagnetic radiation is strong, and great interference is generated on other electronic equipment and communication facilities, so that the daily life of people is seriously influenced, and the health of human beings is harmed. Therefore, it is necessary to load microwave absorbing materials on the surface of the equipment to reduce the influence of electromagnetic waves on the environment and human body.
The current microwave absorbing materials mainly comprise alloy micro powder, ferrite, rare earth oxide, rubber-based composite materials and the like. Among them, rare earth oxides are widely used by virtue of their excellent wave-absorbing properties. For example "Bi 1-x La x FeO 3 Bi has been studied in the microwave absorption properties of the multiferroic system (Zhongnan university journal, 42 th volume, 11 th, 2011, zhao News, etc.) 1-x La x FeO 3 The microwave electromagnetic response characteristic of the powder crystal in the frequency range of 2-18 GHz shows that the effective absorption bandwidth of the sample reaches 3.4GHz above 10dB and the absorption peak reaches 27.7dB when the thickness of the sample is 2.6mm and x = 0.1. Although the above studies have improved the wave absorption properties of the microwave absorbing materialHowever, the coating is thick, which greatly increases the production cost. With the rapid development of the microwave absorption field, the requirement for the thickness of the microwave absorption material coating is higher and higher. Therefore, there is a need for further improvements in microwave absorbing materials that ensure their excellent wave absorbing properties while reducing their thickness and hence cost.
Disclosure of Invention
The invention aims to provide a microwave absorbing material and a preparation method thereof. The microwave absorbing material provided by the invention is thin in coating thickness and has excellent wave absorbing performance.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a microwave absorbing material, the molecular formula of which is Bi (0～0.3) La (0.7～1) FeO 3 。
Preferably, the molecular formula of the microwave absorbing material is Bi (0.1～0.3) La (0.7～0.9) FeO 3 。
Preferably, the molecular formula of the microwave absorbing material is Bi (0.2～0.3) La (0.7～0.8) FeO 3 。
The invention also provides a preparation method of the microwave absorbing material in the technical scheme, which comprises the following steps:
(1) Mixing metal nitrate with citric acid solution, and carrying out gelation reaction to obtain gel; the metal nitrate comprises three types of bismuth nitrate, lanthanum nitrate and ferric nitrate, or two types of lanthanum nitrate and ferric nitrate;
(2) And (2) drying, ashing and calcining the gel obtained in the step (1) in sequence to obtain the microwave absorbing material.
Preferably, the ratio of the amount of metal ions in the metal nitrate salt to the amount of citric acid in the citric acid solution in step (1) is 1: (1-2).
Preferably, the mass concentration of the citric acid solution in the step (1) is 15.8-16.1%.
Preferably, the temperature of the gelation reaction in the step (1) is 80-100 ℃, and the time of the gelation reaction is 3-4.5 h.
Preferably, the drying temperature in the step (2) is 80-100 ℃, and the drying time is 20-36 h.
Preferably, the ashing temperature in step (2) is 200-300 ℃, and the ashing time is 5-10 min.
Preferably, the calcining temperature in the step (2) is 600-700 ℃, and the calcining time is 5-10 h.
The invention provides a microwave absorbing material, the molecular formula of which is Bi (0～0.3) La (0.7～1) FeO 3 . The microwave absorbing material provided by the invention has multiple polarizations, including space charge polarization, dipole polarization and interface polarization, so that the dielectric loss of the material is reduced, meanwhile, a large number of irregular micropores are formed in the material, the pore size distribution is narrow, multiple reflection channels exist, when electromagnetic waves are emitted into the material, the electromagnetic waves are reflected and scattered for multiple times in the material, so that the electromagnetic waves are attenuated more, and the purpose of reducing the thickness of the material and realizing excellent wave absorption performance is achieved. Experimental results show that the microwave absorbing material provided by the invention can absorb electromagnetic waves in a 2-18 GHz microwave band, the absorption efficiency is more than 90%, and the microwave absorbing material can obtain excellent microwave absorbing performance within the thickness of 1.6-2.0 mm.
Drawings
FIG. 1 is an XRD pattern of a microwave absorbing material prepared in examples 1 to 4;
FIG. 2 shows Bi prepared in examples 1 to 4 (0～0.3) La (0.7～1) FeO 3 A reflectivity loss plot for a microwave absorbing material having a thickness of 2 mm;
FIG. 3 shows LaFeO prepared in example 1 3 A reflectance loss plot of the microwave absorbing material;
FIG. 4 shows Bi prepared in example 2 0.1 La 0.9 FeO 3 A reflectance loss plot of the microwave absorbing material;
FIG. 5 shows Bi prepared in example 3 0.2 La 0.8 FeO 3 A reflectance loss plot of the microwave absorbing material;
FIG. 6 shows Bi prepared in example 4 0.3 La 0.7 FeO 3 Reflectance loss plot of microwave absorbing material.
Detailed Description
The invention provides a microwave absorbing material, the molecular formula of which is Bi (0～0.3) La (0.7～1) FeO 3 Further preferably Bi (0.1～0.3) La (0.7～0.9) FeO 3 More preferably Bi (0.2～0.3) La (0.7～0.8) FeO 3 Most preferably Bi 0.3 La 0.7 FeO 3 . In the present invention, the microwave absorbing material Bi (0～0.3) La (0.7～1) FeO 3 The microwave absorbing material has multiple polarizations, including space charge polarization (a large number of gaps and cavities exist in the microwave absorbing material and generate space charge polarization as a polarization center), dipole polarization (increase of Bi doping amount causes increase of lattice defects in the microwave absorbing material and increase of dipoles in the material to cause aggravation of dipole polarization) and interface polarization (after the microwave absorbing material is mixed with paraffin to prepare a composite material, multiple phases exist in the composite material, when electromagnetic waves enter the material, charge accumulation can be generated between the phase and the phase interface to generate interface polarization), dielectric loss of the material is reduced, meanwhile, a large number of irregular micropores exist in the material, the pore size distribution is narrow, multiple reflection channels exist, and the electromagnetic waves are reflected and scattered for multiple times after entering the material to cause greater electromagnetic wave attenuation, so that the purpose of reducing the thickness of the material and realizing excellent wave absorbing performance is achieved.
In the present invention, when the microwave absorbing material contains Bi, bi is used 3+ Rare earth element La substituted for A site 3 + Leading the crystal structure to change, leading the Fe-O-Fe bond angle to generate spin inclination, changing the dielectric constant of the wave-absorbing material, leading the imaginary part of the complex dielectric constant to increase, leading the dielectric loss to microwave to increase, increasing the natural resonance absorption peak by doping Bi element, simultaneously moving the absorption peak to the low-frequency area, leading the generation of oxygen vacancy, in order to ensure the charge conservation, fe 2+ With Fe 3+ The transition between electrons is intensified, the conductivity of the material is increased, and the dielectric is formedThe real part of the electric constant is enhanced, and the wave absorbing performance of the microwave absorbing material is further improved.
The microwave absorbing material provided by the invention absorbs electromagnetic waves in a 2-18 GHz wave band, and the wave absorbing peak shows a double-peak trend along with the change of frequency, shows a stronger broadband characteristic, and has certain stability and stronger oxidation resistance.
The invention also provides a preparation method of the microwave absorbing material in the technical scheme, which comprises the following steps:
(1) Mixing metal nitrate with citric acid solution, and carrying out gelation reaction to obtain gel; the metal nitrate comprises bismuth nitrate, lanthanum nitrate and ferric nitrate or lanthanum nitrate and ferric nitrate;
(2) And (2) drying, ashing and calcining the gel obtained in the step (1) in sequence to obtain the microwave absorbing material.
Mixing metal nitrate with citric acid solution, and carrying out gelation reaction to obtain gel; the metal nitrate comprises three types of bismuth nitrate, lanthanum nitrate and ferric nitrate, or two types of lanthanum nitrate and ferric nitrate. In the present invention, the bismuth nitrate is preferably bismuth nitrate pentahydrate; the lanthanum nitrate is preferably lanthanum nitrate hexahydrate, and the ferric nitrate is preferably ferric nitrate nonahydrate. In the present invention, the purity of the metal nitrate is preferably 99.9% or more. The source of the metal nitrate is not particularly limited in the present invention, and a commercially available product known to those skilled in the art may be used. In the present invention, when the metal nitrate is bismuth nitrate, lanthanum nitrate and iron nitrate, the ratio of the amounts of the substances of bismuth nitrate, lanthanum nitrate and iron nitrate is preferably (0 to 0.3): (0.7-1): 1, more preferably (0.2 to 0.25): (0.8-0.85): 1; when the metal nitrate is lanthanum nitrate and iron nitrate, the ratio of the amounts of the lanthanum nitrate and the iron nitrate is preferably (0.7 to 1): 1, more preferably (0.8 to 0.85): 1. in the invention, the metal nitrate can be completely decomposed by heating, impurities are not introduced during the subsequent high-temperature treatment of the sol-gel method, and an oxidizing atmosphere can be provided.
In the present invention, the mass concentration of the citric acid solution is preferably 15.8% to 16.1%, and more preferably 15.9% to 16.0%. In the present invention, the citric acid solution is preferably obtained by mixing citric acid and distilled water. The operation of mixing the citric acid and the distilled water is not particularly limited in the invention, and the technical scheme for preparing the mixed material which is well known to the technical personnel in the field can be adopted. The source of each component in the citric acid solution is not particularly limited in the present invention, and commercially available products well known to those skilled in the art may be used. In the invention, the citric acid is used as a complexing agent, plays a role of complexing metal ions and can ensure the generation of gel.
In the present invention, the ratio of the amount of metal ions in the metal nitrate to the amount of citric acid in the citric acid solution is preferably 1: (1-2), more preferably 1: (1-1.5). In the present invention, the cost can be reduced when the ratio of the amount of the metal ions in the metal nitrate to the amount of the substance of citric acid in the citric acid solution is within the above range.
The operation of mixing the metal nitrate and the citric acid solution is not particularly limited in the invention, and the technical scheme for preparing the mixed material, which is well known to those skilled in the art, can be adopted.
In the present invention, the temperature of the gelation reaction is preferably 80 to 100 ℃, more preferably 80 to 90 ℃; the time for the gelation reaction is preferably 3 to 4.5 hours, more preferably 3.5 to 4 hours. In the present invention, the gelation reaction is preferably carried out under stirring conditions. In the present invention, the rotation speed of the stirring is preferably 200 to 250r/min. In the present invention, the gelation reaction is preferably carried out in a constant temperature water bath. The type of the constant-temperature water bath kettle is not particularly limited, and instruments and equipment well known to those skilled in the art can be adopted. In the invention, the metal nitrate and the citric acid solution are mixed, and in the gelation reaction process, the metal nitrate forms red viscous gel through hydrogen bonds under the complexation of citric acid, so that the gel is obtained.
After the gel is obtained, the microwave absorbing material is obtained by sequentially drying, ashing and calcining the gel. In the present invention, the drying temperature is preferably 80 to 100 ℃; the drying time is preferably 20 to 36 hours. The drying operation is not particularly limited in the present invention, and a drying operation known to those skilled in the art may be employed.
In the present invention, the ashing temperature is preferably 200 to 300 ℃, more preferably 250 to 300 ℃; the time for the ashing is preferably 5 to 10min. In the present invention, the ashing is preferably performed in an electron oven. The type of the electronic oven is not particularly limited in the present invention, and the electronic oven can be made by using instruments and equipment well known to those skilled in the art. In the present invention, the ashing can be used to remove organic substances and impurities in the gel before calcination.
In the present invention, the temperature of the calcination is preferably 600 to 700 ℃, more preferably 650 to 700 ℃; the calcination time is preferably 5 to 10 hours. In the present invention, the calcination is preferably carried out in a muffle furnace. The muffle furnace is not particularly limited in type, and instruments and equipment well known to those skilled in the art can be adopted. In the present invention, when the calcination temperature is in the above range, pure LaFeO can be obtained 3 Phase, and can effectively prevent the increase of Bi volatilization quantity, so that the Bi element enters LaFeO 3 Lattice, forming a solid solution.
The preparation method of the microwave absorbing material provided by the invention can obtain the wave absorbing material through gelation reaction, drying, ashing and calcining, has a simple preparation process, and is suitable for batch production.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Example 1
Step (1), according to the molecular formula LaFeO 3 5.35g of lanthanum nitrate hexahydrate and 4.99g of ferric nitrate nonahydrate (the mass ratio of lanthanum nitrate hexahydrate to ferric nitrate nonahydrate is 1)) The molar ratio of the citric acid to the citric acid is 1:1, weighing 5.21g of citric acid, mixing the citric acid with distilled water to obtain a citric acid solution (the mass concentration of the citric acid solution is 16.1%), then adding lanthanum nitrate and ferric nitrate into the citric acid solution for mixing, putting the obtained solution into a water bath kettle, continuously stirring at constant temperature and magnetic force (the stirring speed is 250 r/min) at 80 ℃, and carrying out gelation reaction for 3 hours to obtain gel;
and (2) drying the gel obtained in the step (1) in a forced air drying oven at 80 ℃ for 20h, ashing the obtained dried substance at 300 ℃ for 5min, putting the treated dried substance into a muffle furnace, and calcining the dried substance at 700 ℃ in an air atmosphere for 10h to obtain a microwave absorbing material, namely LaFeO 3 。
Example 2
Step (1), bi 0.1 La 0.9 FeO 3 Weighing 0.72g of bismuth nitrate pentahydrate, 4.81g of lanthanum nitrate hexahydrate and 4.99g of ferric nitrate nonahydrate (the mass ratio of the substances of the bismuth nitrate pentahydrate, the lanthanum nitrate hexahydrate and the ferric nitrate nonahydrate is 0.1;
and (2) drying the gel obtained in the step (1) in a forced air drying oven at 80 ℃ for 20h, ashing the obtained dried substance at 300 ℃ for 5min, putting the treated dried substance into a muffle furnace, and calcining the dried substance at 700 ℃ for 10h in an air atmosphere to obtain a microwave absorbing material, namely Bi 0.1 La 0.9 FeO 3 。
Example 3
Step (1) of preparing Bi according to the molecular formula 0.2 La 0.8 FeO 3 1.32g of bismuth nitrate pentahydrate, 4.28g of lanthanum nitrate hexahydrate and 4.99g of ferric nitrate nonahydrate (nitrate pentahydrate) with the purity of more than or equal to 99.9 percent are weighedThe ratio of the amounts of bismuth, lanthanum nitrate hexahydrate and iron nitrate nonahydrate was 0.2:0.8: 1) Then, weighing 5.19g of citric acid according to the molar ratio of metal ions (lanthanum ions, iron ions and bismuth ions) to citric acid being 1;
and (2) drying the gel obtained in the step (1) in a forced air drying oven at 80 ℃ for 20h, ashing the obtained dried substance at 300 ℃ for 5min, putting the treated dried substance into a muffle furnace, and calcining the dried substance at 700 ℃ for 10h in an air atmosphere to obtain a microwave absorbing material, namely Bi 0.2 La 0.8 FeO 3 。
Example 4
Step (1) of preparing Bi according to the molecular formula 0.3 La 0.7 FeO 3 Weighing 1.92g of bismuth nitrate pentahydrate, 3.74g of lanthanum nitrate hexahydrate and 4.99g of ferric nitrate nonahydrate (the mass ratio of the bismuth nitrate pentahydrate, the lanthanum nitrate hexahydrate and the ferric nitrate nonahydrate is 0.3;
and (2) drying the gel obtained in the step (1) in a forced air drying oven at 80 ℃ for 20h, ashing the obtained dried substance at 300 ℃ for 5min, putting the treated dried substance into a muffle furnace, and calcining the dried substance at 700 ℃ for 10h in an air atmosphere to obtain a microwave absorbing material, namely Bi 0.3 La 0.7 FeO 3 。
Prepared in examples 1 to 4XRD detection is carried out on the microwave absorbing material, the detection result is shown in figure 1, and figure 1 is the XRD spectrum of the microwave absorbing material prepared in the examples 1-4. As can be seen from FIG. 1, bi is present at a calcination temperature of 700 ℃ in the case of (0～0.3) La (0.7～1) FeO 3 Pure LaFeO can be obtained from the microwave absorbing material 3 And (4) phase.
The microwave absorbing materials prepared in examples 1 to 4 were subjected to a reflectance loss test at a thickness of 2.0mm, and the test results are shown in fig. 2, and fig. 2 is a graph showing the reflectance loss at a thickness of 2.0mm of the microwave absorbing materials prepared in examples 1 to 4. As can be seen from FIG. 2, bi (0～0.3) La (0.7～1) FeO 3 The material moves to a low-frequency region along with the increase of Bi content, the minimum reflectivity peak value is gradually increased, the minimum reflectivity peak values are all smaller than-10 dB (the absorptivity is larger than 90%), when the Bi content is 0,0.1,0.2 and 0.3, the minimum reflectivity peak frequencies are 14GHz,12.8GHz,12GHz and 11.5GHz respectively, and the minimum reflectivity peak values are correspondingly-16.32 dB, -21.45dB, -22.44dB and-27 dB, which shows that the microwave absorbing material has excellent microwave absorbing performance in the frequency band of 10-18 GHz.
The microwave absorbing material prepared in examples 1 to 4 was mixed with paraffin to prepare a ferrite composite wave-absorbing material, and the reflectivity of the material was tested.
The measuring method comprises the following steps: the microwave absorbing material prepared in the embodiments 1 to 4 comprises the following powders: paraffin = 3: 1 (mass ratio), making coaxial samples with the outer diameter and the inner diameter of 7mm and 3mm respectively and the thickness of 3-3.5 mm, measuring the complex permeability and the complex dielectric constant of the sample in the 2-18 GHz frequency band respectively by adopting an Agilent N5230C vector network analyzer, and then calculating and simulating the reflectivity R of the single-layer wave-absorbing material by adopting the following formula:
in the formula, epsilon r 、μ r And d is the relative dielectric constant, the relative permeability and the thickness of the wave-absorbing material respectively, f is the frequency of the electromagnetic wave, and C is the propagation speed of the electromagnetic wave in the free space (namely the propagation speed of the electromagnetic wave in the free space)Speed of light), j is an imaginary unit.
A. For LaFeO 3 The results of calculating the reflectivities R of the simulated single-layer wave-absorbing material with the thicknesses of 2.0mm, 2.2mm, 2.4mm and 2.6mm are shown in FIG. 3, and FIG. 3 shows the LaFeO prepared in example 1 3 Reflectance loss plot of microwave absorbing material. It can be seen from fig. 3 that, as the matching thickness increases, the reflection ratio increases first and then decreases, and when the matching thickness is 2.2mm, the optimum microwave absorption performance is obtained at 13.44GHz, the minimum reflectivity peak is about-21.32 dB (the absorption rate is about 99%), and the optimum bandwidth effect is obtained (the maximum bandwidth effect is about: (2))<-10dB (absorption rate)>90％))3.2GHz。
B. For Bi 0.1 La 0.9 FeO 3 The results of calculating the reflectivities R of the simulated single-layer wave-absorbing material with the thicknesses of 1.8mm,2.0mm and 2.2mm are shown in FIG. 4, and FIG. 4 shows that Bi prepared in example 2 is shown in FIG. 4 0.1 La 0.9 FeO 3 Reflectance loss plot of microwave absorbing material. As can be seen from fig. 4, the reflectivity shows a decreasing trend with the increase of the matching thickness, and when the matching thickness is 1.8mm, the optimal microwave absorption performance is obtained at 13.20GHz, the maximum value of the reflectivity is about-24.02 dB (the absorptivity is about 99.60%), and the optimal frequency modulation effect is obtained (c), (d), and (d) in the maximum value<-10dB (absorption rate)>90％))4.48GHz。
C. For Bi 0.2 La 0.8 FeO 3 The calculation simulates the reflectivity R of the single-layer wave-absorbing material with the thickness of 1.6mm,1.8mm and 2.0mm respectively, and the result is shown in figure 5, and figure 5 shows that the Bi prepared in the embodiment 3 is Bi 0.2 La 0.8 FeO 3 A reflectivity loss plot for the microwave absorbing material. As can be seen from fig. 5, the reflectance shows a tendency of decreasing first and then increasing as the matching thickness increases, and the optimum microwave absorption performance is obtained at 11.84GHz at a matching thickness of 2.0mm, with a maximum value of reflectance of about-22.44 dB (absorption rate of about 99.43%). And obtain the optimum wide frequency effect (c:)<-10dB (absorptivity)>90％))2.24GHz。
D. For Bi 0.3 La 0.7 FeO 3 The calculation simulates the reflectivities R of the single-layer wave-absorbing material with the thicknesses of 1.6mm,1.8mm,2.0mm and 2.2mm respectively, and the result is shown in FIG. 6, wherein FIG. 6 is a graphBi prepared in example 4 0.3 La 0.7 FeO 3 Reflectance loss plot of microwave absorbing material. It can be seen from fig. 6 that the minimum reflectance peak is less than-10 dB (absorption) in all thicknesses>90%). When the matching thickness is 2.0mm, the minimum reflectivity peak value is about-26.30 dB (the absorptivity is about 99.77%) at 11.36GHz, and the optimum frequency modulation effect (the maximum frequency modulation effect) is obtained<-10dB (absorption rate)>90％))2.48GHz。
As can be seen from the above examples and comparative examples, the perovskite structure microwave absorbing material provided by the invention can absorb electromagnetic waves in a 2-18 GHz microwave band, has a wide absorption band and high absorption efficiency (more than 90%), has good stability and oxidation resistance, and can obtain excellent microwave absorption performance when the thickness of the coating is thin within 1.6-2.0 mm, which indicates that the microwave absorbing material provided by the invention has a thin coating and excellent wave absorption performance.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (1)
1. Microwave absorbing material Bi (0.1~0.3) La (0.7~0.9) FeO 3 The application of the material in microwave absorption is characterized in that the microwave absorption material Bi (0.1~0.3) La (0.7~0.9) FeO 3 The material can absorb electromagnetic waves in a 2-18GHz microwave band, has wide absorption band and absorption efficiency of more than 90 percent, has good stability and oxidation resistance, and can obtain excellent microwave absorption performance when the thickness of the coating is thin within 1.6-2.0 mm;
the microwave absorbing material Bi (0.1~0.3) La (0.7~0.9) FeO 3 The preparation method comprises the following steps:
(1) Mixing metal nitrate with citric acid solution, and carrying out gelation reaction to obtain gel; the metal nitrate is three of bismuth nitrate, lanthanum nitrate and ferric nitrate;
(2) Subjecting the step (1)The obtained gel is sequentially dried, ashed and calcined to obtain the microwave absorbing material Bi (0.1~0.3) La (0.7~0.9) FeO 3 ；
In the step (1), the ratio of the metal ions in the metal nitrate to the amount of the citric acid in the citric acid solution is 1:1;
the ashing temperature in the step (2) is 200 to 300 ℃, and the ashing time is 5 to 10min;
the calcining temperature in the step (2) is 600-700 ℃, and the calcining time is 5-10 h.
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| CN101269842A (en) * | 2008-05-07 | 2008-09-24 | 中国科学院电工研究所 | Method for preparing BiFeO3 nano-particle and fine particle |
| CN102019184B (en) * | 2010-12-27 | 2012-12-26 | 内蒙古大学 | Preparation method of novel perovskite photocatalyst containing bismuth |
| CN102167821B (en) * | 2011-03-24 | 2013-06-12 | 南昌航空大学 | Preparation method of lanthanum-doped barium ferrite-polyaniline composite material microwave absorbent |
| CN103771847B (en) * | 2014-01-02 | 2015-06-03 | 陕西科技大学 | La0.1Bi0.9FeO3/BiY2Fe5O12 magnetoelectric composite powder and preparation method thereof |
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| CN111205078A (en) * | 2020-01-13 | 2020-05-29 | 桂林电子科技大学 | Bi1-xNdxFeO3Preparation method of rare earth ferrite magnetic wave-absorbing material |
| CN111196721A (en) * | 2020-01-13 | 2020-05-26 | 桂林电子科技大学 | La1-xBixFeO3Rare earth ferrite magnetic material and preparation method thereof |
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Application publication date: 20201106 Assignee: Guangxi yunzhishuo Energy Technology Co.,Ltd. Assignor: GUILIN University OF ELECTRONIC TECHNOLOGY Contract record no.: X2022450000477 Denomination of invention: A microwave absorbing material and its preparation method Granted publication date: 20221021 License type: Common License Record date: 20221229 |
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