CN104925868A - Alpha-LiFeO2 nanocrystalline-graphene composite material, preparation method thereof and application - Google Patents

Alpha-LiFeO2 nanocrystalline-graphene composite material, preparation method thereof and application Download PDF

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CN104925868A
CN104925868A CN201510290018.4A CN201510290018A CN104925868A CN 104925868 A CN104925868 A CN 104925868A CN 201510290018 A CN201510290018 A CN 201510290018A CN 104925868 A CN104925868 A CN 104925868A
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nanocrystalline
lifeo
composite material
graphene composite
graphene
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孙根班
吴红
杨晓晶
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Beijing Normal University
Beijing Normal University Science Park Technology Development Co Ltd
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Beijing Normal University
Beijing Normal University Science Park Technology Development Co Ltd
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Abstract

The embodiment of the invention discloses an alpha-LiFeO2 nanocrystalline-graphene composite material, which is formed by compositing alpha-LiFeO2 nanocrystallines and graphene; the graphene is flaky and serves as a base of the composite material; the alpha-LiFeO2 nanocrystallines are dispersed on the graphene. The embodiment of the invention also discloses a preparation method of the alpha-LiFeO2 nanocrystalline-graphene composite material and an application of the preparation method in the field of electromagnetic wave absorption. In the alpha-LiFeO2 nanocrystalline-graphene composite material prepared by the embodiment of the invention, the alpha-LiFeO2 nanocrystallines are orderly inlaid on two-dimensional graphene nanosheets to avoid an agglomeration phenomenon, and the composite material shows a better absorbing property than that of the alpha-LiFeO2 nanocrystallines; besides, as a thermal decomposition one-pot method is adopted, the alpha-LiFeO2 nanocrystalline-graphene composite material is composited in one step, and simpleness, convenience, quickness and cost reduction are realized.

Description

α-LiFeO 2nanocrystalline-graphene composite material, its preparation method and application
Technical field
The present invention relates to absorbing material field, particularly a kind of α-LiFeO 2nanocrystalline-graphene composite material, its preparation method and application.
Background technology
In recent years, the telecommunication technology developed rapidly is just being widely used in military affairs, civilian and industrial circle.Militarily, the fast development of the radar exploration technique, constitutes serious threat to the existence of military target, therefore develops the radar signal of target such as stealthy technique shielding warship, aircraft etc., has become the important development direction of military technique.In addition, civilian and industrial, telecommunication technology brings to the life of people and also creates a large amount of electromagnetic radiation easily simultaneously.The electromagnetic interference (EMI) that the electromagnetic environment worsened produces not only works the mischief to the daily communication of people, computer and various electronic system, and can bring threat to people are healthy.Therefore, for hertzian wave have high-selenium corn capacity, wide absorption region, resistance of oxidation is good, quality is light absorbing material research cause the great attention of people.
Current Li ferrite is as typical iron, nontoxic, environmental friendliness, and is easy to get at a low price, is therefore considered to very potential absorbing material.Wherein, as the α-LiFeO of one of Li ferrite 2, because its density is little, be only 4.38g/cm 3, therefore more favourable as absorbing material.But, α-LiFeO 2nanocrystalline ratio is easier to reunite, and is difficult to control its size and dispersiveness, so absorbing property is affected.
Summary of the invention
For solving the problem, the embodiment of the invention discloses a kind of α-LiFeO 2nanocrystalline-graphene composite material, described α-LiFeO 2nanocrystalline-graphene composite material solves α-LiFeO 2nanocrystalline ratio is easier to the problem of reuniting, and generates monodispersed α-LiFeO 2nanocrystalline-graphene composite material.Technical scheme is as follows:
A kind of α-LiFeO 2nanocrystalline-graphene composite material, by α-LiFeO 2nanocrystalline and Graphene is composited, described Graphene in the form of sheets and as the substrate of described matrix material, described α-LiFeO 2nanocrystallinely to be dispersed on described Graphene.
In preferred implementations more of the present invention, described α-LiFeO 2nanocrystalline is face-centered cubic phase, and in (111), (200), there is diffraction peak in (220) face.
In preferred implementations more of the present invention, described α-LiFeO 2nanocrystalline particle diameter is 2 ~ 15nm.
In preferred implementations more of the present invention, reflection loss value is-9.30 ~-21.00dB.
A kind of above-mentioned α-LiFeO 2the preparation method of nanocrystalline-graphene composite material, comprises the following steps:
A) graphite oxide is joined in oleyl amine, disperse, obtain the first dispersion liquid;
B) ferric acetyl acetonade, a hydronium(ion) Lithium Oxide 98min and stearylamine are added in described first dispersion liquid, form the first mixed solution, after the first mixed solution being heated to the first preset temp under whipped state, carry out first time isothermal holding, then continue, under whipped state, to be heated to the second preset temp, carry out second time isothermal holding, obtain the first reaction solution, all standing process is carried out to the first reaction solution;
C) separation is carried out to the first reaction solution after all standing process and obtain α-LiFeO 2nanocrystalline-graphene composite material head product, to α-LiFeO 2nanocrystalline-graphene composite material head product carries out washing, centrifugal and drying treatment, obtains α-LiFeO 2nanocrystalline-graphene composite material.
In preferred implementations more of the present invention, the grams of described graphite oxide is 10 ~ 50 with the ratio of the mole number of described ferric acetyl acetonade, and the number that rises of described oleyl amine is 10 ~ 50 with the ratio of the mole number of described ferric acetyl acetonade.
In preferred implementations more of the present invention, the mol ratio of a described hydronium(ion) Lithium Oxide 98min and described ferric acetyl acetonade is 2 ~ 20, and the grams of described stearylamine is 0.25 ~ 4 with the ratio of the mole number of described ferric acetyl acetonade.
In preferred implementations more of the present invention, described first preset temp is 90 DEG C ~ 160 DEG C, and the time of isothermal holding described first time is more than 5min, and described second preset temp is more than 200 DEG C, and the time of described second time isothermal holding is more than 30min.
In preferred implementations more of the present invention, described all standing process is carried out by adding ethanol or acetone realizes in the first reaction solution to the first reaction solution.
Above-mentioned α-LiFeO 2nanocrystalline-graphene composite material is in the application in electromagnetic wave absorption field.
The embodiment of the present invention has the following advantages:
1) α-LiFeO prepared 2in nanocrystalline-graphene composite material, α-LiFeO 2nanocrystallinely " to inlay " in two-dimensional graphene nanometer sheet in an orderly manner, avoid agglomeration.
2) α-LiFeO prepared 2nanocrystalline-graphene composite material, compared to α-LiFeO 2nanocrystalline, show better absorbing property.
3) thermolysis " one kettle way " is adopted, one-step synthesis α-LiFeO 2nanocrystalline-graphene composite material, easy, quick, saving cost.
Certainly, arbitrary product of the present invention is implemented or method might not need to reach above-described all advantages simultaneously.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is graphite oxide (GO), Graphene (GN) and α-LiFeO 2the XRD figure of nanocrystalline-graphene composite material, wherein Fig. 1 (a) is the XRD figure of graphite oxide (GO), and Fig. 1 (b) is the XRD figure of Graphene (GN), and Fig. 1 (c) is α-LiFeO 2the XRD figure of nanocrystalline-graphene composite material;
Fig. 2 is graphite oxide (GO), Graphene (GN) and α-LiFeO 2the Raman spectrogram of nanocrystalline-graphene composite material, wherein Fig. 2 (a) is the Raman spectrogram of graphite oxide (GO), and Fig. 2 (b) is the Raman spectrogram of Graphene (GN), and Fig. 2 (c) is α-LiFeO 2the Raman spectrogram of nanocrystalline-graphene composite material;
Fig. 3 is α-LiFeO 2the electron microscopy image analysis of nanocrystalline-graphene composite material, wherein Fig. 3 (a) is α-LiFeO 2the scanning electron microscope (SEM) photograph of nanocrystalline-graphene composite material, Fig. 3 (b), (c) are α-LiFeO 2the transmission electron microscope figure of nanocrystalline-graphene composite material, Fig. 3 (d) are α-LiFeO 2the high resolution transmission electron microscopy figure of nanocrystalline-graphene composite material, that insert Fig. 3 (d) is selected area electron diffraction figure;
Fig. 4 is α-LiFeO 2the graph of a relation of the microwave reflection rate loss value of nanocrystalline-graphene composite material and thickness of sample, frequency.
Embodiment
Graphene is because having large surface-area, and quality is light, fabulous electroconductibility, snappiness and erosion resistance and become perfect substrate, using Graphene as base material and α-LiFeO 2the nanocrystalline material carrying out compound gained, can make α-LiFeO 2nanocrystallinely can to disperse well, and due to Graphene be dielectric loss consumption material, therefore, by Graphene and magnetic loss material α-LiFeO 2nano crystal constructed α-LiFeO 2nanocrystalline-graphene composite material, has and is better than α-LiFeO 2nanocrystalline absorption of electromagnetic wave performance.Based on analysis above, the invention provides α-LiFeO 2nanocrystalline-graphene composite material, its preparation method and application.
α-LiFeO 2nanocrystalline-graphene composite material is by α-LiFeO 2nanocrystalline and Graphene (GN) is composited, and above-mentioned Graphene is two-dimensional sheet and as the substrate of described matrix material, above-mentioned α-LiFeO 2nanocrystallinely to be dispersed on above-mentioned Graphene.Wherein, above-mentioned α-LiFeO 2nanocrystalline is face-centered cubic phase, and in (111), (200), there is diffraction peak in (220) face, and particle diameter is 2 ~ 15nm, and median size is 7nm.Above-mentioned α-LiFeO 2the reflection loss value of nanocrystalline-graphene composite material is-9.30 ~-21.00dB.
Above-mentioned α-LiFeO 2the preparation method of nanocrystalline-graphene composite material, comprises the following steps:
A) graphite oxide (GO) is joined in oleyl amine, disperse, obtain the first dispersion liquid.The amount of graphite oxide and oleyl amine is that benchmark is selected, therefore in step b according to following ferric acetyl acetonade) after be described.The dispersing mode of above-mentioned dispersion can be ultrasonic disperse, vibrating dispersion or its combination, is preferably ultrasonic disperse.Time the present invention of dispersion does not do concrete restriction at this, is as the criterion, in general, can disperses 1 ~ 3 hour can obtain finely dispersed dispersion liquid.
B) ferric acetyl acetonade, a hydronium(ion) Lithium Oxide 98min and stearylamine are added in above-mentioned first dispersion liquid, form the first mixed solution, after the first mixed solution being heated to the first preset temp under whipped state, carry out first time isothermal holding, then continue, under whipped state, to be heated to the second preset temp, carry out second time isothermal holding, obtain the first reaction solution, all standing process is carried out to the first reaction solution.
In optimal ways more of the present invention, the grams (g) of above-mentioned graphite oxide is 10 ~ 50 with the ratio of the mole number (mol) of above-mentioned ferric acetyl acetonade, is more preferably 20.
In optimal ways more of the present invention, the number that rises of above-mentioned oleyl amine is 10 ~ 50 with the ratio of the mole number of above-mentioned ferric acetyl acetonade, is more preferably 20 ~ 40.
In optimal ways more of the present invention, the mol ratio of an above-mentioned hydronium(ion) Lithium Oxide 98min and above-mentioned ferric acetyl acetonade is 2 ~ 20, is more preferably 4.
In optimal ways more of the present invention, the grams of above-mentioned stearylamine is 0.25 ~ 4 with the ratio of the mole number of above-mentioned ferric acetyl acetonade.Adding stearylamine in the present invention, it can be used as confinement agent to make for limiting nanocrystalline growth uneven, be conducive to forming monodispersed α-LiFeO 2nanocrystalline, stearylamine is also a kind of reductive agent simultaneously, if content is too much, and can by Fe 3+be reduced to Fe 2+, be unfavorable for the generation of target product.Therefore, more preferably the grams of above-mentioned stearylamine is 0.5 ~ 2 with the ratio of the mole number of above-mentioned ferric acetyl acetonade, more preferably 1.
In optimal ways more of the present invention, above-mentioned first preset temp is 90 DEG C ~ 160 DEG C, is more preferably 120 DEG C.In optimal ways more of the present invention, the time of isothermal holding above-mentioned first time is more than 5min.Be heated to the first preset temp and the object of carrying out first time isothermal holding is because in the present context, α-LiFeO 2nanocrystalline easy nucleation, and can grow lentamente, therefore be conducive to forming mono-dispersed nano brilliant, also can remove the moisture in reaction system in addition, therefore above-mentioned first the fixed time more long-acting fruit better, but consideration time cost, more preferably above-mentioned first fixed time is 15min ~ 60min, more preferably 30min.In optimal ways more of the present invention, under whipped state can be under magnetic agitation state.
In optimal ways more of the present invention, above-mentioned second preset temp is more than 200 DEG C.Boiling point due to oleyl amine is 348 ~ 350 DEG C, therefore the second preset temp can be considered to select between 200 DEG C and the boiling point of oleyl amine, that is, more preferably above-mentioned second preset temp is 200 ~ 350 DEG C, and preferably above-mentioned second preset temp is 200 ~ 340 DEG C further.In optimal ways more of the present invention, the time of above-mentioned second time isothermal holding is more than 30min, and the time, more long-acting fruit was better, but considers time cost, and more preferably the time of above-mentioned second time isothermal holding is 60 ~ 180min, more preferably 120min.
In order to make the first reaction solution cooling and stopped reaction and carry out all standing process to the first reaction solution.The known method that all standing process can adopt those skilled in the art is carried out to the first reaction solution, is not specifically limited at this.In optimal ways more of the present invention, above-mentioned all standing process is carried out by adding ethanol or acetone realizes in the first reaction solution to the first reaction solution.
C) separation is carried out to the first reaction solution after all standing process and obtain α-LiFeO 2nanocrystalline-graphene composite material head product, to α-LiFeO 2nanocrystalline-graphene composite material head product carries out washing, centrifugal and drying treatment, obtains α-LiFeO 2nanocrystalline-graphene composite material.
Above-mentioned separation can adopt the known method of those skilled in the art, is not specifically limited at this.In optimal ways more of the present invention, adopt centrifugal mode to be separated, this centrifugal centrifugal method that can adopt those skilled in the art's routine, is not specifically limited at this.The object of carrying out being separated in this step is to isolate α-LiFeO from the first reaction solution 2nanocrystalline-graphene composite material head product.
Above-mentioned washing can adopt and well known to a person skilled in the art that ordinary method is carried out, and is not specifically limited at this.In optimal ways more of the present invention, adopt the mode that normal hexane and acetone alternately wash.
Above-mentioned to α-LiFeO 2nanocrystalline-graphene composite material head product carries out washing, the centrifugal centrifugal method that can adopt those skilled in the art's routine in centrifugal and drying treatment, is not specifically limited at this.The object adopting centrifugal mode to carry out being separated in this step is in order to by the α-LiFeO after carrying out washing treatment 2nanocrystalline-graphene composite material head product is separated with washing composition.
Above-mentioned drying can adopt the drying means of those skilled in the art's routine, is not specifically limited at this, such as, adopt vacuum drying mode.
According to the α-LiFeO that aforesaid method obtains 2nanocrystalline-graphene composite material may be used for electromagnetic wave absorption.
It should be noted that all raw materials that the embodiment of the present invention adopts do not have special restriction to its source, commercially buy or make by oneself further.Such as, in the present invention, Graphite Powder 99 is purchased from Qingdao Nan Shu graphite company limited; Oleyl amine is purchased from Shanghai Jing Chun biochemical technology limited-liability company (Aladdin, 80-90%); Ferric acetyl acetonade purchased from Shanghai Jing Chun biochemical technology limited-liability company (Aladdin), analytical pure; One hydronium(ion) Lithium Oxide 98min purchased from Chemical Reagent Co., Ltd., Sinopharm Group, analytical pure; Stearylamine purchased from Chemical Reagent Co., Ltd., Sinopharm Group, analytical pure.
In addition, the embodiment of the present invention is at preparation α-LiFeO 2the experimental installation adopted in the process of nanocrystalline-graphene composite material, is the equipment that this area is general, all can commercially buy.Contriver believes, those skilled in the art can select suitable experimental installation by the description of technical solution of the present invention completely, and the present invention does not carry out concrete restriction and explanation to experimental installation at this.
It should be noted that further, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operational zone, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.
In order to further illustrate the present invention, be described technical scheme of the present invention below in conjunction with specific embodiment, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
The preparation of graphite oxide
Graphite oxide (GO) used by raw material of the present invention.Preparation method for graphite oxide belongs to prior art, and those skilled in the art can adopt suitable preparation method as required.Present invention employs following making method, adopt the graphite oxide that the method makes, degree of oxidation is high, and dispersion effect is in organic solvent good.
The present invention adopts the Hummers method of improvement to prepare graphite oxide, prepares α-LiFeO as embodiment 1 ~ embodiment 5 2the raw material of nanocrystalline-graphene composite material.
Take 5g Graphite Powder 99,5gNaNO 3h dense with 230mL 2sO 4, be placed in ice-water bath, slowly add 30gKMnO while stirring 4.
After about 45min, remove ice-water bath, put into 35 DEG C of water-baths, slowly add 460mL distilled water, this process is about 30min, and product graduates into brown by black.
Be put in afterwards in 98 DEG C of oil baths and be incubated 15min.
After withdrawing from oil bath, add 1400mL warm water, stir, add 100mLH 2o 2, now product becomes golden yellow.Filter, be rare HCl solution washing of 5% with massfraction, then use distilled water wash 4 times, without SO to filtrate 4 2-till.Products therefrom, in 70 DEG C of air dryings, obtains 4.8g graphite oxide.
Embodiment 1
A) homemade 40mg graphite oxide (GO) is joined in 40mL oleyl amine, carry out ultrasonic disperse 2 hours, obtain the first dispersion liquid;
B) by 2mmol (0.7063g) ferric acetyl acetonade Fe (acac) 3, 8mmol (0.3357g) hydronium(ion) Lithium Oxide 98min (LiOHH 2o) and 2g stearylamine be added in above-mentioned first dispersion liquid, 120 DEG C are heated under maintenance magnetic agitation state, insulation 30min, then continue to be heated to 300 DEG C under maintenance magnetic agitation state, insulation 120min, obtain the first reaction solution, add 20mL ethanol and all standing process is carried out to the first reaction solution.
C) carry out obtaining α-LiFeO with the rotating speed centrifugation 5min of 10000 revs/min to the first reaction solution after all standing process 2nanocrystalline-graphene composite material head product, then uses normal hexane and acetone to α-LiFeO 2nanocrystalline-graphene composite material head product carries out alternately washing 3 times, then with the centrifugal 5min of the rotating speed of 10000 revs/min, finally under condition, carries out drying at 40 DEG C, obtains α-LiFeO 2nanocrystalline-graphene composite material.
Embodiment 2
A) homemade 20mg graphite oxide (GO) is joined in 20mL oleyl amine, carry out ultrasonic disperse 2 hours, obtain the first dispersion liquid;
B) by 2mmol (0.7063g) ferric acetyl acetonade Fe (acac) 3, 4mmol (0.1678g) hydronium(ion) Lithium Oxide 98min (LiOHH 2o), 0.5g stearylamine is added in above-mentioned first dispersion liquid, 160 DEG C are heated under maintenance magnetic agitation state, insulation 5min, then continue to be heated to 340 DEG C under maintenance magnetic agitation state, insulation 60min, obtains the first reaction solution, adds 20mL ethanol and carry out all standing process to the first reaction solution.
C) carry out obtaining α-LiFeO with the rotating speed centrifugation 5min of 10000 revs/min to the first reaction solution after all standing process 2nanocrystalline-graphene composite material head product, then uses normal hexane and acetone to α-LiFeO 2nanocrystalline-graphene composite material head product carries out alternately washing 3 times, then with the centrifugal 5min of the rotating speed of 10000 revs/min, finally under vacuum condition, carries out drying at 40 DEG C, obtains α-LiFeO 2nanocrystalline-graphene composite material.
Embodiment 3
A) homemade 40mg graphite oxide (GO) is joined in 60mL oleyl amine, carry out ultrasonic disperse 2 hours, obtain the first dispersion liquid;
B) by 2mmol (0.7063g) ferric acetyl acetonade Fe (acac) 3, 10mmol (0.4196g) hydronium(ion) Lithium Oxide 98min (LiOHH 2o) and 3g stearylamine be added in above-mentioned first dispersion liquid, 90 DEG C are heated under maintenance magnetic agitation state, insulation 60min, then continue to be heated to 200 DEG C under maintenance magnetic agitation state, insulation 180min, obtain the first reaction solution, add 20mL ethanol and all standing process is carried out to the first reaction solution.
C) carry out obtaining α-LiFeO with the rotating speed centrifugation 5min of 10000 revs/min to the first reaction solution after all standing process 2nanocrystalline-graphene composite material head product, then uses normal hexane and acetone to α-LiFeO 2nanocrystalline-graphene composite material head product carries out alternately washing 3 times, then with the centrifugal 5min of the rotating speed of 10000 revs/min, finally under vacuum condition, carries out drying at 40 DEG C, obtains α-LiFeO 2nanocrystalline-graphene composite material.
Embodiment 4
A) homemade 50mg graphite oxide (GO) is joined in 80mL oleyl amine, carry out ultrasonic disperse 2 hours, obtain the first dispersion liquid;
B) by 2mmol (0.7063g) ferric acetyl acetonade Fe (acac) 3, 15mmol (0.6294g) hydronium(ion) Lithium Oxide 98min (LiOHH 2o) and 3g stearylamine be added in above-mentioned first dispersion liquid, 100 DEG C are heated under maintenance magnetic agitation state, insulation 15min, then continue to be heated to 240 DEG C under maintenance magnetic agitation state, insulation 120min, obtain the first reaction solution, add 20mL ethanol and all standing process is carried out to the first reaction solution.
C) carry out obtaining α-LiFeO with the rotating speed centrifugation 5min of 10000 revs/min to the first reaction solution after all standing process 2nanocrystalline-graphene composite material head product, then uses normal hexane and acetone to α-LiFeO 2nanocrystalline-graphene composite material head product carries out alternately washing 3 times, then with the centrifugal 5min of the rotating speed of 10000 revs/min, finally under vacuum condition, carries out drying at 40 DEG C, obtains α-LiFeO 2nanocrystalline-graphene composite material.
Embodiment 5
A) homemade 100mg graphite oxide (GO) is joined in 100mL oleyl amine, carry out ultrasonic disperse 2 hours, obtain the first dispersion liquid;
B) by 2mmol (0.7063g) ferric acetyl acetonade Fe (acac) 3, 40mmol (0.8392g) hydronium(ion) Lithium Oxide 98min (LiOHH 2o) and 8g stearylamine be added in above-mentioned first dispersion liquid, 140 DEG C are heated under maintenance magnetic agitation state, insulation 15min, then continue to be heated to 280 DEG C under maintenance magnetic agitation state, insulation 120min, obtain the first reaction solution, add 40mL ethanol and all standing process is carried out to the first reaction solution.
C) with the rotating speed centrifugation 5min of 10000 revs/min, α-LiFeO is obtained to the first reaction solution after all standing process 2nanocrystalline-graphene composite material head product, then uses normal hexane and acetone to α-LiFeO 2nanocrystalline-graphene composite material head product carries out alternately washing 3 times, then with the centrifugal 5min of the rotating speed of 10000 revs/min, finally under vacuum condition, carries out drying at 40 DEG C, obtains α-LiFeO 2nanocrystalline-graphene composite material.
α-LiFeO obtained by embodiment 1 ~ 5 2the complexion of nanocrystalline-graphene composite material is similar to, so the figure characterizing it and analyze also is similar to, considers file length, with the α-LiFeO obtained by embodiment 1 2nanocrystalline-graphene composite material is example, carries out characterizing and analyzing.
Characterize and analyze
1, XRD (X-ray diffraction, X-ray diffraction) analyzes
α-the LiFeO that the x-ray powder diffraction instrument (model: X Pert PRO MPD) adopting Dutch PANalytical company to produce is prepared the homemade material oxidation graphite of the present invention, Graphene and the present invention 2nanocrystalline-graphene composite material (α-LiFeO 2/ GN) carry out XRD sign, XRD figure is as shown in Figure 1.
In FIG, (a), (b), (c) are graphite oxide (GO) respectively, the α-LiFeO of Graphene (GN) and preparation 2the XRD figure of nanocrystalline-graphene composite material.In Fig. 1 (a), the interlamellar spacing of the GO obtained by being oxidized graphite is (original graphite is about ), there is a typical diffraction peak in a ° position, 2 θ=10.9 simultaneously, and the typical diffractive peak of original graphite disappears (2 θ=26.5 °), illustrate that the GO obtained effectively has been oxidized, therefore can verify that fabricated material graphite oxide of the present invention meets the requirements.In Fig. 1 (b), within the scope of 20-30 °, occurred an obvious diffraction corona, simultaneously 43.2 ° have a weak diffraction peak, (002) and (100) face of corresponding GN respectively, show that decolorizing carbon exists, and GO is reduced to GN.In Fig. 1 (c), the α-LiFeO of preparation 2nanocrystalline-graphene composite material, in the diffraction peak that 2 θ are 37.5 °, 43.4 °, 63.1 ° places, corresponding (111), (200), (220) face respectively, do not produce the diffraction peak that Fig. 1 (a) and Fig. 1 (b) is corresponding simultaneously, illustrate at α-LiFeO 2in nanocrystalline-graphene composite material, there is not GO, may be that GO is reduced in order to unbodied GN, and the situation that GN does not superpose (not having the peak of GN).Further indexing, that obtain is the face-centered cubic α-LiFeO of pure phase 2(JCPDS card no.70-2711), spacer is Fm3m.In addition, the obvious broadening of XRD diffraction peak of nano composite material in figure, infers that the nanoparticle size obtained is less.
2, Raman spectrum analysis
Raman spectrometer (Horiba JobinYvon company produces, model LavRAMAramis) is adopted to prove at synthesis α-LiFeO 2in the process of nanocrystalline-graphene composite material, the degree that GO is reduced.
Fig. 2 is graphite oxide, Graphene and α-LiFeO 2the Raman spectrogram of nanocrystalline-graphene composite material.From natural graphite to graphite oxide, be gradient to Graphene again, there occurs huge structural changes, and this change can show from Raman figure.We prove at synthesis α-LiFeO with Raman collection of illustrative plates 2in the process of nanocrystalline-graphene composite material, the degree that GO is reduced.In the Raman spectrum of carbon material, respectively 1345cm -1, 1570cm -1neighbouring peak, be called D band, G band, they are Raman characteristic peaks of C atomic crystal.D band corresponds to the unordered sp of graphite 3hydbridized carbon atoms vibrates, relevant with randomness and lattice imperfection; G band corresponds to the hexagonal lattice sp of two dimension 2the carbon atom plane vibration of hydridization is relevant to the stacking provisions of material.As shown in Fig. 2 (a), the D band of graphite oxide and the strength ratio of G band, i.e. I d/ I gfor 0.93:1, the I of the graphite reported d/ I gbe about 0.27:1, as seen along with introducing and the sp of oxygen-containing functional group 2hydbridized carbon atoms region is destroyed, and graphite oxide lattice imperfection increases, so its I d/ I gthan the I of graphite d/ I ggreatly.As shown in Fig. 2 (b), the I of shown Graphene d/ I gfor 1.31:1, compared with graphite oxide, the I of Graphene d/ I gincreasing to some extent, may be because in reduction process, caused by the lamella of Graphene diminishes.As shown in Fig. 2 (c), α-LiFeO 2the I of nanocrystalline-graphene composite material d/ I gfor 1.20:1, show that graphite oxide has been reduced in the composite.
3, electron microscopy image analysis
Utilize scanning electron microscope: FESEM, acceleration voltage of 5kV, S-4800, Hitachi; Transmission electron microscope: HRTEM, an acceleration voltage of 200kV, JEM-2010 carries out electron microscopy image analysis.
Fig. 3 is α-LiFeO 2the Electronic Speculum figure of nanocrystalline-graphene composite material.Fig. 3 (a) is α-LiFeO 2the scanning electron microscope (SEM) photograph (SEM) of nanocrystalline-graphene composite material, because the resolving power of scanning electron microscope is lower, so only to find out that large-area sightless nanoparticle growth is on graphene nanometer sheet.But high-visible from the transmission electron microscope (TEM) of Fig. 3 (b) and Fig. 3 (c), nanocrystallinely " to inlay " in two-dimensional graphene nanometer sheet in an orderly manner, there is no the phenomenon of reunion.In addition, Graphene and α-LiFeO 2profile very clear, α-LiFeO 2nanocrystalline size dimension is even, particle diameter about 7nm.Meanwhile, what be not dispersed in outside Graphene is nanocrystalline, does not also have the Graphene that big area is exposed, shows successfully to obtain α-LiFeO 2the matrix material of nanocrystalline and Graphene.Because Graphene is thinner, easily there is fold and reunion.But repeatedly survey in the process of SEM and TEM and do not find the Graphene that big area is exposed and the phenomenon that Graphene is reunited, show α-LiFeO 2nanocrystalline growth is on Graphene, and also serve the effect stoping Graphene to be reunited, this is also consistent with XRD figure, does not have the peak of Graphene overlap in XRD figure equally simultaneously.Can see lattice phase clearly from the high resolution transmission electron microscopy (HRTEM) of Fig. 3 (d), spacing of lattice is 0.206nm, corresponding α-LiFeO 2nanocrystalline (200) face.The figure be inserted in Fig. 3 (d) is selected area electron diffraction figure (SAED), from SAED, α-LiFeO 2nanocrystalline-graphene composite material is polycrystalline structure, and has clear and definite spacing 0.237,0.206 and 0.147nm, corresponding (111), (200) and (220) crystal face.These results are consistent with XRD figure.
4, absorbing property result
For comparing and evaluating α-LiFeO 2the microwave absorbing property of nanocrystalline-graphene composite material, α-LiFeO 2nanocrystalline-graphene composite material and paraffin Homogeneous phase mixing (α-LiFeO 2the weight fraction of nanocrystalline-graphene composite material is 60%, paraffin does not have absorption of electromagnetic wave), be assembled into an absorption of electromagnetic wave device, external diameter and internal diameter are 7.00mm and 3.04mm respectively, adopt Agilent E8362B vector network analyzer, test and carry out under fixing frequency and thickness of sample, reflection loss value (RL) calculates according to microwave transmission theory, and formula is as follows:
Z in = Z 0 μ r / ϵ r tanh [ j ( 2 πfd / c ) μ r ϵ r ]
RL(dB)＝20log|(Z in-Z 0)/(Z in+Z 0)|
Wherein f representative is microwave frequency, and what d represented is absorption agent thickness, and what c represented is the light velocity, Z inrepresent the input impedance of absorption agent.
The variation relation of reflection loss value with frequency of different thickness of sample has been surveyed in 1.0-18.0GHz range of frequency.That Fig. 4 (a), (b) represent respectively is α-LiFeO 2nanocrystalline and α-LiFeO 2the reflection loss value of nanocrystalline-graphene composite material is with the variation relation of frequency.From Fig. 4 (a), (b), along with the increase of thickness of sample, occur that the absorption frequency of minimal losses value moves to low frequency, simultaneously stability intensity increases, and absorption band increases.Comparative composite and α-LiFeO 2nanocrystalline reflection loss value, can find that matrix material is at low frequency (1GHz-6GHz), intermediate frequency (7GHz-12GHz), the absorbing property of high frequency (13GHz-18GHz) is obviously better than α-LiFeO 2nanocrystalline absorbing property.The absorption intensity being embodied in matrix material increases, and absorption band broadens.Think that, when reflection loss value reaches below-10dB, this absorbing material has actual application value widely.α-LiFeO 2the strongest nanocrystalline microwave absorbing occurs it being at 9mm, 16.9GHz place, and minimal reflection loss value reaches-7.8dB.And for α-LiFeO 2nanocrystalline-graphene composite material, when thickness of sample be 2,3,4mm, the strongest microwave absorbing appears at 13.9GHz ,-16.0dB respectively, 8.7GHz ,-9.3dB and 6.0GHz ,-9.5dB; When thickness of sample be 5,6mm, curve there are respectively two absorption peaks (4.6GHz ,-11.1dB, 17.0GHz ,-16.4dB and 3.5GHz ,-12.8dB, 12.6GHz ,-14.6dB).Especially when 2mm, 13.9GHz, reflection loss value reaches-16.0dB, and within the scope of 11.9-16.2GHz, microwave absorbing is all less than-10dB simultaneously.The strongest microwave absorbing of matrix material reaches-21.0dB, appears at 7mm, 10.5GHz and 9.0mm, 7.9GHz simultaneously.As can be seen from upper analysis, α-LiFeO 2nanocrystallinely show better absorbing property with the nano composite material of Graphene, meet the requirement to novel wave-absorbing material " gently ", " thin ", " by force ", " wide ".By regulating the thickness of sample, electromagnetic consumable can cover 1-18GHz frequency band, proves the actual application value that this material absorbs by regulating thickness to reach all wave band.
Each embodiment in this specification sheets all adopts relevant mode to describe, between each embodiment identical similar part mutually see, what each embodiment stressed is the difference with other embodiments.
The foregoing is only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.All any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., be all included in protection scope of the present invention.

Claims (10)

1. a α-LiFeO 2nanocrystalline-graphene composite material, is characterized in that: by α-LiFeO 2nanocrystalline and Graphene is composited, described Graphene in the form of sheets and as the substrate of described matrix material, described α-LiFeO 2nanocrystallinely to be dispersed on described Graphene.
2. α-LiFeO as claimed in claim 1 2nanocrystalline-graphene composite material, is characterized in that: described α-LiFeO 2nanocrystalline is face-centered cubic phase, and in (111), (200), there is diffraction peak in (220) face.
3. α-LiFeO as claimed in claim 1 or 2 2nanocrystalline-graphene composite material, is characterized in that: described α-LiFeO 2nanocrystalline particle diameter is 2 ~ 15nm.
4. α-LiFeO as claimed in claim 1 2nanocrystalline-graphene composite material, is characterized in that: reflection loss value is-9.30 ~-21.00dB.
5. α-the LiFeO as described in Claims 1 to 4 2the preparation method of nanocrystalline-graphene composite material, is characterized in that, comprises the following steps:
A) graphite oxide is joined in oleyl amine, disperse, obtain the first dispersion liquid;
B) ferric acetyl acetonade, a hydronium(ion) Lithium Oxide 98min and stearylamine are added in described first dispersion liquid, form the first mixed solution, after the first mixed solution being heated to the first preset temp under whipped state, carry out first time isothermal holding, then continue, under whipped state, to be heated to the second preset temp, carry out second time isothermal holding, obtain the first reaction solution, all standing process is carried out to the first reaction solution;
C) separation is carried out to the first reaction solution after all standing process and obtain α-LiFeO 2nanocrystalline-graphene composite material head product, to α-LiFeO 2nanocrystalline-graphene composite material head product carries out washing, centrifugal and drying treatment, obtains α-LiFeO 2nanocrystalline-graphene composite material.
6. preparation method as claimed in claim 5, it is characterized in that: the grams of described graphite oxide is 10 ~ 50 with the ratio of the mole number of described ferric acetyl acetonade, the number that rises of described oleyl amine is 10 ~ 50 with the ratio of the mole number of described ferric acetyl acetonade.
7. preparation method as claimed in claim 5, is characterized in that: the mol ratio of a described hydronium(ion) Lithium Oxide 98min and described ferric acetyl acetonade is 2 ~ 20, and the grams of described stearylamine is 0.25 ~ 4 with the ratio of the mole number of described ferric acetyl acetonade.
8. preparation method as claimed in claim 5, it is characterized in that: described first preset temp is 90 DEG C ~ 160 DEG C, the time of isothermal holding described first time is more than 5min, and described second preset temp is more than 200 DEG C, and the time of described second time isothermal holding is more than 30min.
9. preparation method as claimed in claim 5, is characterized in that: describedly carry out all standing process by adding ethanol or acetone realizes in the first reaction solution to the first reaction solution.
10. α-the LiFeO as described in any one of Claims 1 to 4 2nanocrystalline-graphene composite material is in the application in electromagnetic wave absorption field.
CN201510290018.4A 2015-05-29 2015-05-29 Alpha-LiFeO2 nanocrystalline-graphene composite material, preparation method thereof and application Pending CN104925868A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103173189A (en) * 2013-03-06 2013-06-26 西北工业大学 Method for preparing reduced graphene oxide/ferroferric oxide nano-grade wave-absorbing materials

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103173189A (en) * 2013-03-06 2013-06-26 西北工业大学 Method for preparing reduced graphene oxide/ferroferric oxide nano-grade wave-absorbing materials

Non-Patent Citations (1)

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HONG WU, ET AL.: "Synthesis, characterization and electromagnetic performance of nanocomposites of graphene with α-LiFeO2 and β-LiFe5O8", 《JOURNAL OF MATERIALS CHEMISTRY C》 *

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Application publication date: 20150923