Abstract
We are presenting the investigation of the optical, magnetic, and photoinduced superparamagnetic properties of single-domain γ-Fe2O3 nanoparticles (NPs) with diameters of about 2.5 nm formed in second-generation poly(propylene imine) dendrimer. The optical absorption studies indicated direct allowed transition with the band gap (4.5 eV), which is blue shift with respect to the value of the bulk material. Low-temperature blocking of the NPs magnetic moments at 18 K is determined by SQUID measurements. The influence of pulsed laser irradiation on the superparamagnetic properties of γ-Fe2O3 NPs was studied by EPR spectroscopy. It has been shown that irradiation of the sample held in vacuo and cooled in zero magnetic field to 6.9 K leads to the appearance of a new EPR signal, which decays immediately after the irradiation is stopped. The appearance and disappearance of this new signal can be repeated many times at 6.9 K when we turn on/turn off the laser. We suppose that the generation of conduction band electrons by irradiation into the band gap of the γ-Fe2O3 changes the superparamagnetic properties of NPs.
Graphical Abstract
![](http://media.springernature.com/lw685/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Figa_HTML.gif)
Features of the behavior of single-domain γ-Fe2O3 nanoparticles formed in dendrimer were found by UV-Vis and EPR spectroscopy: “blue” shift in optical absorption, a significant increase in the band gap width and variation of superparamagnetic properties under light irradiation.
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Fig1_HTML.gif)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Fig2_HTML.gif)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Fig3_HTML.gif)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Fig4_HTML.gif)
![](http://media.springernature.com/m312/springer-static/image/art%3A10.1007%2Fs11051-015-2890-z/MediaObjects/11051_2015_2890_Fig5_HTML.gif)
References
Bean CP, Livingston JD (1959) Superparamagnetism. J Appl Phys 30:120–30129. doi:10.1063/1.2185850
Berger R, Kliava J, Bissey J-C, Baïetto V (1998) Superparamagnetic resonance of annealed iron-containing borate glass. J Phys 10:8559–8572
Berger R, Bissey J-C, Kliava J, Daubric H, Estournes C (2001) Temperature dependence of superparamagnetic resonance of iron oxide nanoparticles. J Magn Magn Mater 234:535–544. doi:10.1016/S0304-8853(01)00347-X
Bhattacharyya D, Chaudhuri S, Pal AK (1992) Bandgap and optical transitions in thin films from reflectance measurements. Vacuum 43:313–316
Chakrabarti S, Ganguli D, Chaudhuri S (2004) Optical properties of γ-Fe2O3 nanoparticles dispersed on sol–gel silica spheres. Phys E 24:333–342. doi:10.1016/j.physe.2004.06.036
Chirita M, Grozescu I (2009) Fe2O3—nanoparticles, physical properties and their photochemical and photoelectrochemical applications. Chem Bull “Politehnica” Univ (Timisoara) 54:1
Chudnovsky EM, Gunther L (1988) Quantum tunneling of magnetization in small ferromagnetic particles. Phys Rev Lett 60:661–664
Domracheva NE, Pyataev AV, Manapov RA, Gruzdev MS (2011) Magnetic resonance and Mössbauer studies of superparamagnetic γ-Fe2O3 nanoparticles encapsulated into liquid-crystalline Poly(propylene imine) dendrimers. Chem Phys Chem 12:3009–3019. doi:10.1002/cphc.201100363
Dronskowski R (2001) The little maghemite story: a classic functional material. Adv Funct Mater 11:27–29
Efros AL, Rosen M (2000) The electronic structure of semiconductor nanocrystals. Ann Rev Mater 30:475–521
Ekimov AI, Onushchenko AA (1981) Quantum size effect in semiconductor three-dimensional microcrystals. Pis’ma Zh Eksp Teor Fiz 34:363–366
Franckevicius M, Tamuliene J, Babonas J, Simkiene I, Rasteniene L, Kulbickas A, Irzikevicius A, Vaisnoras R (2011) UV spectral features of poly (propylene imine) dendrimers. Lith J Phys 51:207–211
Jacobs IS, Bean CP (1963) In: Rado GT, Shul H (eds) Magnetism III, vol Chap. 6. Academic, New York
Kharlamova MV, Sapoletova NA, Eliseev AA, Suzdalev IP, Maksimov YUV, Lukashin AV, Tret’yakov YUD (2007) Optical properties of nanostructured γ iron oxide. Dokl Chem 415:176–179
Kharlamova MV, Sapoletova NA, Eliseev AA, Lukashin AV (2008) Optical properties of γ-ferric oxide nanoparticles in a mesoporous silica matrix. Tech Phys Lett 34:288–291
Kudo A, Miseki Y (2009) Heterogeneous photocatalyst materials for water splitting. Chem Soc Rev 38:253–278. doi:10.1039/b800489g
Leggett AJ, Chakravarty S, Dorsey AT, Fisher MPA, Garg A, Zuerger W (1987) Dynamics of the dissipative two-state system. Rev Mod Phys 59:1–85
Macdonald IR, Howe RF, Saremi-Yarahmadi S, Wijayantha KGU (2010) Photoinduced superparamagnetism in nanostructured α-Fe2O3. J Phys Chem Lett 1:2488. doi:10.1021/jz100650w
Murray CB, Kagan CR, Bawendi MG (1995) Self-organization of CdSe nanocrystallites into three-dimensional quantum dot superlattices. Science 270:1335–1338
Neel L (1948) Proprietes magnetiques des ferrites: ferrimagnetisme et antiferromagnetisme. Ann Phys 3:137–198
Pankov JI (1971) Optical processes in semiconductors. Printice-Hall, New Jersey, p 34
Parker FT, Foster MW, Margulies DT, Berkowitz AE (1993) Spin canting, surface magnetization, and finite-size effects in γ-Fe2O3 particles. Phys Rev 47:7885–7891
Raikher YuL, Stepanov VI (1994) Ferromagnetic resonance in a suspension of single-domain particles. Phys Rev B 50:6250. doi:10.1103/PhysRevB.50.6250
Waychunas GA (1991) Crystal chemistry of oxides and oxyhydroxides. Rev Miner Geochem 25:11–68
Wijayantha KGU, Auty DH (2005) Encyclopaedia of materials: science and technology updates. Elsevier, Oxford, p 15
Ziolo RF, Giannelis EP, Weinstein BA, O’Horo MP, Ganguly BN, Mehrotra V, Russell MW, Huffman DR (1992) Matrix-mediated synthesis of nanocrystalline γ-Fe2O3: a new optically transparent magnetic material. Science 257:219–223
Acknowledgments
We thank Yu. N. Shvachko and D. V. Starichenko for magnetic measurements. We gratefully acknowledge the financial support for this work by RAS Presidium program No. 24 and in part by the RFBR, project No. 11-03-01028.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Domracheva, N.E., Vorobeva, V.E., Gruzdev, M.S. et al. Blue shift in optical absorption, magnetism and light-induced superparamagnetism in γ-Fe2O3 nanoparticles formed in dendrimer. J Nanopart Res 17, 83 (2015). https://doi.org/10.1007/s11051-015-2890-z
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s11051-015-2890-z