isolation and characterization of nanosheets containing few layers of the aurivillius family of...

Isolation and characterization of nanosheets containing few layersof the Aurivillius family of oxides and metal-organic compounds

M.B. Sreedhara a, B.E. Prasad a, Monali Moirangthema, R. Murugavel b, C.N.R. Rao a,n

a Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science and Sheik Saqr Laboratory, Jawaharlal NehruCentre for Advanced Scientic Research, Jakkur P.O., Bangalore 560064, Indiab Department of Chemistry, Indian Institute of TechnologyBombay, Powai, Mumbai 400076, India

a r t i c l e i n f o

Article history:Received 13 December 2013Received in revised form21 January 2014Accepted 15 February 2014

Keywords:Aurivillius oxidesLayered bismuth oxidesExfoliationFew-layer metal-organic compoundsLayered phosphonatesLayered copper complexes

a b s t r a c t

Nanosheets containing few-layers of ferroelectric Aurivillius family of oxides, Bi2An1BnO3n3 (whereABi3 , Ba2 etc. and BTi4 , Fe3 etc.) with n3, 4, 5, 6 and 7 have been prepared by reaction withn-butyllithium, followed by exfoliation in water. The few-layer samples have been characterized byTyndall cones, atomic force microscopy, optical spectroscopy and other techniques. The few-layer specieshave a thickness corresponding to a fraction of the c-parameter along which axis the perovskite layersare stacked. Magnetization measurements have been carried out on the few-layer samples containingiron. Few-layer species of a few layered metal-organic compounds have been obtained by ultrasonicationand characterized by Tyndall cones, atomic force microscopy, optical spectroscopy and magneticmeasurements. Signicant changes in the optical spectra and magnetic properties are found in thefew-layer species compared to the bulk samples. Few-layer species of the Aurivillius family of oxidesmay nd uses as thin layer dielectrics in photovoltaics and other applications.

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1. Introduction

Since the discovery of graphene [1], there has been intenseinterest in the exfoliation of layered materials to prepare single or few-layered nanosheets since such species possess uniqueproperties of value [2,3]. There has been considerable effort madeto exfoliate layered metal dichalcogenides such as MoS2 and WS2and some inorganic layered compounds [2,3]. It is indeed desirableto prepare few-layer species of various important layered inor-ganic materials and examine their properties. In this contest,exfoliating layered metal oxides into individual akes by liquidphase exfoliation or mechanical means assumes importance.Recently, few-layer MoO3 has been prepared by Li intercalationand ultrasonication [4]. The exfoliated layered oxides possessinghigh surface area and distinct electronic properties may havepotential applications in catalysis, supercapacitors, gas storageand sensor technologies [46]. One of the well-known familiesof layered materials is that of Aurivillius oxides, a class of layeredperovskites with strong covalent bonding in the molecular layerand van der Waals interaction between the layers [79]. Theselayered oxides form a homologous series of compounds with thegeneral formula Bi2An1BnO3n3 built from regular intergrowths of

uorite-like (Bi2O2)2 layers alternating with (An1BnO3n1)2 per-ovskite layers along the (00l) direction. Generally, ABi3 , La3 ,Sr2 and BFe3 , Ti4 , in these materials and there are n perovskitelayers in one formula unit. Some of Aurivillius oxides containing ironexhibit strong antiferromagnetic ordering with the Nel temperatureincreasing with the increasing number of perovskite layers [10]. Thestrong antiferromagnetic interaction is due to FeOFe superex-change interaction in the perovskite layers which dominates overthe diamagnetic interaction in the Bi2O2 layers [10,11]. The Aurivilliusoxides also exhibit ferroelectricity and other interesting properties[9,1214]. The ability to exfoliate layers of the Aurivillius oxides byintercalation of guest species into the van der Waals gap allows toengineer their properties which may indeed be useful in practicalapplications. Preparation of layered titanates by delamination hasbeen reported [15]. We have exfoliated several members of Aurivil-lius oxides (n3, 4, 5, 6 and 7) by chemical Li intercalation using n-butyllithium followed by reaction in water and characterized thefew-layer materials thus produced.

Another class of layered materials of interest where few-layerspecies can be prepared by exfoliation is that of metal-organicframework (MOF) compounds with layered structures. There hasbeen some interest in preparation of nanosheets of MOFs byultrasonication [2,16,17]. Nanosheets of these materials are char-acterized by Tyndall effect and other methods. We have carriedout exfoliation of layered Cu complexes and also transition metalphosphonates examined the optical and magnetic properties of

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Journal of Solid State Chemistry

http://dx.doi.org/10.1016/j.jssc.2014.02.0200022-4596 & 2014 Elsevier Inc. All rights reserved.

n Corresponding author.E-mail address: [email protected] (C.N.R. Rao).

Please cite this article as: M.B. Sreedhara, et al., J. Solid State Chem. (2014), http://dx.doi.org/10.1016/j.jssc.2014.02.020i

Journal of Solid State Chemistry ()

the exfoliated species. The present study demonstrates thatexfoliated species of layered oxides and MOFs constitutes a classof materials with potential uses. It is likely that exfoliatednanosheets of the layered oxides and MOFs may provide newvenues for engineering and designing useful materials, specially bydepositing the nanosheets on appropriate substrates.

2. Experimental

2.1. Synthesis of Aurivillius oxides and their exfoliation

Aurivillius compounds of the general formula Bin1Fen3Ti3O3n3 (n3, 4, 5, 6 and 7) were synthesized by the solid statemethod. Required amounts of pure Bi2O3, Fe2O3 and TiO2 (99.9%Sigma Aldrich) were nely ground (with 5 wt% excess Bi2O3 tocompensate for the volatilization) pressed into a 12 mm circularpellet by applying pressure and heated in several steps to get thedesired phase. The heating sequence for Bi4Ti3O12 and Bin1Fen3Ti3O3n3 are 800 1C/8 h and 8001000 1C/2448 h (for n4, 24 h;n5, 32 h; n6, 40 h and n7, 48 h) at a rate of 5 1C/min. Afterevery 8 h, the pellet was cooled to room temperature ground,pressed into a pellet and heated again to get the pure phase. Inorder to prepare single or few-layer samples we exfoliatedcompounds by lithium intercalation and deintercalation [18,19].This was carried out by the reaction between 3 mmol-excessn-BuLi in hexane (1.6 M, Acros) with ground Aurivillius oxidepowder in a N2 atmosphere n-BuLi was added drop by drop towell ground powder at 0 1C and the mixture slowly brought toroom temperature and stirred for 72 h. The lithiated productswere washed several times to remove the excess n-BuLi. Theproducts were black in color it is due to the partial reduction ofbismuth and titanium. The exfoliation was done by oxidativelithium deintercalation by treating the lithiated Aurivillius oxideswith deionized water under ultrasonication for 4 h followed bydialysis in a stream of deionized water for 48 h. The product wasthoroughly washed and centrifuged until the pH of supernatantbecame 7. This method leads to exfoliation of layers as could beobserved by the gradual color change from black to the expectedcolor of the compound. During the exfoliation reaction the Li goesto solution as LiOH with the evolution of hydrogen from waterthereby favouring the formation of few-layers.

2.2. Synthesis and exfoliation of layered metal-organic compounds

(Cu(Hbpa)2)n: To a stirred solution of H2bpa (0.201 g, 1.0 mmol)in methanol (30 mL) was added hexaaquocopper(II) perchlorate(0.372 g, 1.0 mmol) in one shot and the resulting light-bluesolution was stirred at room temperature for 2 h, during whichtime a blue precipitate of 2 is formed. The reaction mixture wasltered, and the clear blue solution was kept at room temperaturefor crystallization [20]. Blue crystals of [Cu(Hbpa)2]n which are ofX-ray diffraction quality appeared after 2 days. Combined yield ofprecipitate and crystals: 0.45 g, (90%). Mp. 215220 1C. Anal. Calcd.for C14H14CuN2O8P2: C, 36.26; H, 3.04; N, 6.04. Found: C, 35.62; H,2.89; N, 6.58. IR (KBr, cm1): 3318 (s), 2332 (m), 1608 (s), 1571 (s),1509 (s), 1478 (s), 1300 (s), 1184 (s), 1068 (s), 953 (s), 710 (w), 504(w). 298 K: 1.84 B. EPR (average g factor ) 2.1.

[Cu6(H2L)3(H2O)10]n 4H2O: In order to synthesize this compound,(0.130 g, 0.32 mmol) of H6L and hexaaquocopper(II)-perchlorate(0.186 g, 0.32 mmol) were dissolved in deionized water (2 mL). Theresulting light blue solution was stirred for 5 minutes and the pH ofthis clear solution was adjusted to 4.0 using 1 M sodium hydroxidesolution. This clear solution was transferred to a teon beaker andplaced in a stainless-steel jacket and heated at 110 1C. After 3 days atthis temperature, the vessel was slowly cooled to room temperature.

The light green colored microcrystals were collected and washedwith cold methanol [21]. Yield: 0.130 g. Mp: 4250 1C. Anal. Calcd. forC36H77Cu6O40P9 (MW: 1805.9): C, 36.26; H, 3.04. Found: C, 35.62; H,2.89. IR (KBr, cm1): 3438(s), 2923 (m), 2382 (m), 1633 (s), 1433 (m),1383 (s), 1236 (s), 1050 (s), 915 (s), 635 (s), 551 (s). EPR: (average gfactor )2.1. DR UVvis (nm): 387, 660. TGA: temp.range 1C (weightloss): 80250 (3.0%), 450700 (20.66%), 600890 (58.7%). DSC (1C):280 (endo); 480 (endo). MTobs (cm3 K M1)1.71, MTcalcd(cm3 K M1)1.51. eff (25 1C)3.72 BM.

[(C10H13O3P)Co(H2O)]: A solution of Co(OAc)2.H2O (0.249 g,1 mmol) in methanol (20 mL) was added to a stirring solution ofH2L (0U214 g, 1 mmol) in methanol (10 mL) at room temperature.Blue color precipitate obtained immediately and ltered. Theprecipitate was washed with water and methanol several timesand dried under high vacuum [22]. Yield: 0U0842 g (67% basedon Co). M.P.4250 1C. Elemental analysis (anal. calcd (%) forC10H15O4PCo): C, 41.54; H, 5.23. Found: C, 40.13; H, 4.14. FT-IR(KBr, cm1): 3438 (br), 2923 (s), 2855 (m), 1578 (w), 1416 (w), 1039(vs), 986 (s), 850 (s), 586 (w), 521 (w).

[(C10H13O3P)Ni(H2O)]: A solution of Ni(OAc)2. H2O (0.248 g,1 mmol) in methanol (20 mL) was added to a stirring solution ofH2L (0U214 g, 1 mmol) in methanol (10 mL) at room temperature.White solid precipitate obtained immediately and ltered. Theprecipitate was washed with water and methanol several timesand dried under high vacuum. Yield: 0U0742 g (60% based on Ni).M.P.4250 1C. Elemental analysis (anal. calcd (%) for C10H15O4PNi):C, 41.58; H, 5.23. Found: C, 42.12; H, 5.17. FT-IR (KBr, cm1): 3421(br), 2924 (s), 2853 (m), 2344 (br), 1650 (w), 1458 (w), 1090 (vs),1017 (s), 800 (s), 585 (w).

Layered Cu, Co and Ni compounds were exfoliated in ethanol byultrasonication operating at 40 kHz (Branson, B3510E-MT) fordifferent periods of time.

2.3. Characterization

Powder X-ray diffraction (PXRD) patterns were recorded inBruker D8 Discover diffractometer and Rigaku-99 diffractometerusing Cu K radiation. Photoluminescence measurements ofthe bulk and exfoliated copper complexes were recorded inFluorolog-3 spectrophotometer using Horiba Jobin Yvon with Xelamp as light source, Atomic force microscopy (AFM) was per-formed on an Innova atomic force microscope. Transmissionelectron microscopy (TEM) images were recorded using JEOL JEM3010 microscope, tted with a Gatan CCD camera operating at anaccelerating voltage of 300 kV. Electronic absorption spectra wererecorded in a Perkin-Elmer Lambda 900 UV/vis/NIR spectrometerin the diffuse reectance mode. Magnetic measurements werecarried out in SQUID VSM (Quantum Design, U.S.). With thispurpose the few-layer species were deposited on glass/siliconsubstrates and contribution from the substrate subtracted fromthe observed magnetization.

3. Results and discussion

3.1. Aurivillius family of oxides

We have examined bulk as well as few-layer samples of a fewmembers of the Aurivillius family of oxides including Bi4Ti3O12 andthe n4, 5, 6, 7 members of the Bin1Fen3Ti3O3n3 family. Fig. 1shows structures of Bi4Ti3O12 and Bi5Ti3FeO15. The cell parameter cand the number of perovskite layers in these materials are shownin Table 1. Li intercalation in these oxides with n-BuLi, followed byexfoliation in water results in suspensions of few-layer materials.Our results on the exfoliation of Bi4Ti3O12 agree well with those ofKim et al. [18].

M.B. Sreedhara et al. / Journal of Solid State Chemistry () 2


Fig. 2 shows typical PXRD patterns of few-layer samples ofBi5Ti3FeO15 (n4) and Bi7Ti3Fe3O21 (n6) in comparison withthose of bulk samples. All the samples had lamellar structures andthere were no granules. The XRD patterns of the few-layer samplesare generally broader and the intensity of the (00l) reection islower indicating that the destruction of the stacking along the(00l) direction has resulted in the few-layer structures. Clearly Liintercalation and deintercalation leads exfoliation of the layeredstructures. The reason that the (00l) reection is affected isbecause the layers are stacked in this direction with van der Waalsforces between them. Fig. 3 shows AFM images with heightproles of two Aurivillius phases with n3 and 4, revealing thefew-layer nanosheets to be 1.66 and 2.01 nm thick. These valuescorrespond to a fraction of the c-parameter as shown in Table 1.Insets in Fig. 3 show Tyndall scattering of the colloidal suspensionsin ethanol conrming the presence of few-layers in the exfoliatedsamples. We show typical TEM images of few-layer Bi6Ti3Fe2O18and Bi7Ti3Fe3O21 in Fig. 4 to illustrate crystalline features of these

materials: the electron diffraction pattern in Fig. 4(b) shows clearlysingle crystalline character of the nanosheets. Interestingly, thefew-layer species do not show any scrolling unlike single-layerspecies in certain instances.

UVvis spectra of the few-layer materials show blue-shifts ofthe absorption bands relative to the bulk samples due to quantumsize effect (Fig. 5). The absorption is mainly due to excitation fromthe valence band to conduction band, valence band mainlycomprising Bi 6sFe t2gO 2p and conduction band comprisingTi 3dFe eg orbitals. The low energy visible light photoexicitationscorresponds to the electronic excitation to Fe eg orbits from Bi

Fig. 1. Crystal structure of (a) Bi4Ti3O12 and (b) Bi5Ti3FeO15.

Table 1Comparison of AFM layer height with cell parameter and number of perovskitelayers.

Composition Cellparameterc (nm)

No. ofperovskitelayers

AFM layerheight(nm)

Comparison of AFMheight with cellparameter c

Bi4Ti3O12 3.284 3 1.66 Ec/2Bi5Ti3FeO15 4.119 4 2.01 Ec/2Bi6Ti3Fe2O18 4.934 5 1.86 Ec/3Bi7Ti3Fe3O21 5.755 6 1.81 Ec/3

Fig. 2. PXRD patterns of bulk and few-layer samples of Bi5Ti3FeO15 and Bi7Ti3Fe3O21.



6sFe t2gO 2p, the absorption from UV photons arising fromexcitation to Ti 3d orbital because these orbits lie in higher energystates than the Fe eg states. The absorption shoulder in the spectraat visible region may be due to the incorporation of some energylevels of the Fe 3d orbits [14]. In Fig. 5 we show the spectra ofBi5Ti3FeO15 and Bi7Ti3Fe3O21 with absorption maxima at 405 and431 nm respectively in the bulk samples. The corresponding few-layer samples show maxima at 382 and 391 nm respectively.Raman spectra of few-layer and bulk samples were similar justlike in the case of MoO3 [4].

Some of the Aurivillius phases studied by us contain iron andexhibit magnetic properties. Bulk samples of these materials areantiferromagnetic with Nel temperatures 80 K, 160 K, 190 K and220 K for n4, 5, 6 and 7 respectively. We have compared themagnetic properties of bulk and few-layer samples and found thatthe few-layer samples have slightly higher magnetization valuesthan the corresponding bulk material as shown in Fig. 6. This isunderstandable since antiferromagnetic interaction in the bulkmaterial is reduced in the few-layers samples; furthermore thenanosamples would show surface magnetism.

Fig. 3. AFM images of few-layer samples of (a) Bi4Ti3O12 and (b) Bi5Ti3FeO15 prepared by Li intercalation. Inset shows Tyndall effect in the nanosheets dispersions. Bulksample dispersed in ethanol do not show Tyndall cones.

Fig. 4. TEM images of few-layer samples of (a) Bi6Ti3Fe2O18 and (b) Bi7Ti3Fe3O21.The lattice spacing shown in between (111) and (119) planes.

Fig. 5. UVvis spectra of bulk and few-layer samples of Bi5Ti3FeO15 and Bi7Ti3Fe3O21.



3.2. Layered metal-organic compounds

We have carried out the exfoliation of layered metal-organiccompounds by ultrasonication. For example, ethanol dispersionsof layered Cu complexes of the formulae [Cu(Hbpa)2]n and[Cu6(H2L)3(H2O)10]n4H2O (where HbpaC7H7NPO4, H2LC12H21P3O9) were ultrasonicated. After ultrasonication the ethanol dis-persions of [Cu(Hbpa)2]n show Tyndall cones (Fig. 7). In Fig. 7 wealso show the AFM image with the height prole, showing layerthickness to be 1.6 nm and thereby conrming the presence offew-layers of the compound. Fig. 8 shows the photoluminescencespectrum of [Cu(Hbpa)2]n with a band around 400 nm due toligand to metal charge-transfer as in other metal organic frame-works and co-ordination compounds [2325]. What is interestingis that the photoluminescence band shows a large blue-shift to343 nm in the exfoliated sample. Fig. 9 shows the Tyndall coneexhibited by exfoliated [Cu6(H2L)3(H2O)10]n4H2O indicating theformation of the few-layered material. The exfoliated samplealso exhibits a blue-shift of the charge-transfer band from400 nm to 345 nm. We have carried out ultrasonication of twolayered phosphonates Co(C10H13PO3)H2O and Ni(C10H13PO3)H2O.

Fig. 6. FC magnetization for bulk and few-layer samples of Bi5Ti3FeO15 and Bi7Ti3Fe3O21.

Fig. 7. AFM image and demonstration of Tyndall effect in the colloidal suspension containing nanosheets of [Cu(Hbpa)2]n. Dispersion of bulk samples do not showTyndall cones.

Fig. 8. Photoluminescence spectra of bulk and few layer [Cu(Hbpa)2]n.



On ultrasonication, the materials show Tyndall cones which areshown in Fig. 10 in the case of the Ni compound. The AFM imagewith height prole shows a height of 1.7 nm conrming thepresence of few layers in the dispersion after exfoliation. We havecarried out the magnetic susceptibility measurements of bulk andfew-layer samples of the cobalt phosphonate. Fig. 11 presents acomparison of the magnetic susceptibilities of the bulk and thefew-layer samples of the cobalt phosphonate, clearly demonstrat-ing that the canted antiferromagnetism found in the bulk sampledisappears in few-layer sample. This is as expected since longrange ordering cannot occur in the few-layer sample.

4. Conclusions

Reaction with n-butyllithium provides a satisfactory method ofobtaining few-layer species of the members of the Aurivillius

family of oxides with the thickness corresponding to a fractionof the c-parameter. Since the bulk samples of these oxides areferroelectrics, it may be possible to use the few-layer species asthin dielectric lms in photovoltaics and other applications. Few-layer species of layered metal-organic compounds form a newtype of molecular coordination compounds with unique proper-ties. Depositing the exfoliated nanosheets on various substratesand other layered materials can give rise to materials of interest.

Acknowledgements

M B S thanks the Council of Scientic and Industrial Research(CSIR) for a junior research fellowship, Rana Saha for magneticmeasurements and Dr. A. Govindaraj for help.

References

[1] A.K. Geim, K.S. Novoselov, Nat. Mater. 6 (2007) 183191.[2] C.N.R. Rao, H.S.S. Ramakrishna Matte, U. Maitra, Angew. Chem. Int. Ed. 52

(2013) 1316213185.[3] J.N. Coleman, M. Lotya, A. ONeill, S.D. Bergin, P.J. King, U. Khan, K. Young,

A. Gaucher, S. De, R.J. Smith, I.V. Shvets, S.K. Arora, G. Stanton, H.-Y. Kim, K. Lee,G.T. Kim, G.S. Duesberg, T. Hallam, J.J. Boland, J.J. Wang, J.F. Donegan,J.C. Grunlan, G. Moriarty, A. Shmeliov, R.J. Nicholls, J.M. Perkins,E.M. Grieveson, K. Theuwissen, D.W. McComb, P.D. Nellist, V. Nicolosi, Science331 (2011) 568571.

[4] M.B. Sreedhara, H.S.S.R. Matte, A. Govindaraj, C.N.R. Rao, Chem. Asian J.8 (2013) 24302435.

[5] Q.H. Wang, K. Kalantar-Zadeh, A. Kis, J.N. Coleman, M.S. Strano, Nat. Nano7 (2012) 699712.

[6] V. Nicolosi, M. Chhowalla, M.G. Kanatzidis, M.S. Strano, J.N. Coleman, Science340 (2013) 1226419.

[7] B. Aurivillius, Ark. Kemi, 1, 463471.[8] J.L. Hutchison, J.S. Anderson, C.N.R. Rao, Proc. R. Soc. Lond. A 355 (1977)

301312.[9] C.N.R. Rao, B. Raveau, Transition Metal Oxides:Structure, Properties, and

Synthesis of Ceramic Oxides, Wiley-VCH, Weinheim, 1998.[10] A. Srinivas, D.-W. Kim, K.S. Hong, S.V. Suryanarayana, Mater. Res. Bull. 39

(2004) 5561.[11] X.W. Dong, K.F. Wang, J.G. Wan, J.S. Zhu, J.-M. Liu, J. Appl. Phys. 103 (2008)

094101.[12] A. Srinivas, M.M. Kumar, S.V. Suryanarayana, T. Bhimasankaram, Mater. Res.

Bull. 34 (1999) 989996.[13] N.A. Lomanova, V.V. Gusarov, Inorg. Mater. 47 (2011) 420.[14] S. Sun, W. Wang, H. Xu, L. Zhou, M. Shang, L. Zhang, J. Phys. Chem. C 112 (2008)

1783517843.[15] T. Sasaki, M. Watanabe, J. Am. Chem. Soc. 120 (1998) 46824689.[16] P.J. Saines, M. Steinmann, J.-C. Tan, H.H.M. Yeung, W. Li, P.T. Barton,

A.K. Cheetham, Inorg. Chem. 51 (2012) 1119811209.[17] J.-C. Tan, P.J. Saines, E.G. Bithell, A.K. Cheetham, ACS Nano 6 (2011) 615621.[18] J.-Y. Kim, I. Chung, J.-H. Choy, G.-S. Park, Chem. Mater. 13 (2001) 27592761.[19] V. Chevallier, G. Nihoul, V. Madigou, J. Solid State Chem. 181 (2008) 439449.[20] R. Murugavel, M.P. Singh, Inorg. Chem. 45 (2006) 91549156.

Fig. 9. Photoluminescence spectra of bulk and few layer [Cu6(H2L)3(H2O)10]n4H2O.Inset demonstrates Tyndall effect in the colloidal suspension containing nanosheets of[Cu6(H2L)3(H2O)10]n4H2O. Dispersion of bulk samples do not show Tyndall cones.

Fig. 10. AFM image of Ni(C10H13PO3)H2O. The inset demonstrates the Tyndalleffect in the colloidal suspension containing nanosheets. Dispersion of bulksamples do not show Tyndall cones.

Fig. 11. FC magnetization for bulk and few-layer sample of [Co(C10H13PO3)H2O].



[21] M.P. Singh, Metal Phosphoramidate and Phosphonate Based Clusters andFrameworks (Ph.D thesis), IIT Bombay, 2009.

[22] R. Murugavel, M.P. Singh, N. J. Chem. 34 (2010) 18461854.[23] M.D. Allendorf, C.A. Bauer, R.K. Bhakta, R.J.T. Houk, Chem. Soc. Rev. 38 (2009)

13301352.

[24] M.-X. Li, H. Wang, S.-W. Liang, M. Shao, X. He, Z.-X. Wang, S.-R. Zhu, Cryst.Growth Des. 9 (2009) 46264633.

[25] G.-H. Wang, Z.-G. Li, H.-Q. Jia, N.-H. Hu, J.-W. Xu, CrystEngComm 11 (2009)292297.



Isolation and characterization of nanosheets containing few layers of the Aurivillius family of oxides and metal-organic...IntroductionExperimentalSynthesis of Aurivillius oxides and their exfoliationSynthesis and exfoliation of layered metal-organic compoundsCharacterization

Results and discussionAurivillius family of oxidesLayered metal-organic compounds

ConclusionsAcknowledgementsReferences

isolation and characterization of nanosheets containing few layers of the aurivillius family of...

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