Magnetic Nanoparticles: Fabrication, Properties and Applications

$20.00

Description

Magnetic Nanoparticles: Fabrication, Properties and Applications

B.P. Rao, M. Abbas

Magnetic nanoparticles are being widely used as potential materials in several applications, namely, consumer electronics, automobile and biomedical fields. Magnetic nanoparticles compacted in an insulating matrix are shown to be excellent materials for miniaturized high frequency electronic devices. Substituted cobalt ferrites and their self composites are increasingly found suitable for non-contact torque sensors. Functionalized magnetic nanoparticles and core-shell nanostructures would prove beneficial for biomedical applications. In this chapter, some simple preparation routes and common characterization techniques for the study of magnetic nanoparticles are covered. Further, recent advances and future prospects in all three application areas mentioned above are briefly discussed.

Keywords
Magnetic Nanoparticles, Synthesis, Ferrites, Torque Sensor, Biomedical Applications

Published online 4/20/2018, 32 pages

DOI: http://dx.doi.org/10.21741/9781945291692-7

Part of the book on Magnetic Oxides and Composites

References
[1] E.C. Snelling, Soft ferrites: Properties and Applications, 2nd ed., Butterworths Publishing, 1989.
[2] H. Setyawan, F. Fajaroh, W. Widiyastuti, S. Winardi, I. Wuled Lenggoro, N. Mufti, One-step synthesis of silica-coated magnetite nanoparticles by electrooxidation of iron in sodium silicate solution, Journal of Nanoparticle Research, 14 (2012) 807–815. https://doi.org/10.1007/s11051-012-0807-7
[3] L. Caruana, A.L. Costa, M.C. Cassani, E. Rampazzo, L. Peodi, N. Zacceroni, Tailored SiO2-based coatings for dye doped superparamagnetic nanocomposites, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 410 (2012) 111–118. https://doi.org/10.1016/j.colsurfa.2012.06.027
[4] T.Y. Leung, C.Y.Chan, C.Hu, J.C.Hu, P.K.Wong, Photocatalytic disinfection of marine bacteria using fluorescent light, Water Research, 42 (2008) 4827-4837. https://doi.org/10.1016/j.watres.2008.08.031
[5] X. Yu,S.Liu,J.Yu, Superparamagnetic γ-Fe2O3@SiO2@TiO2 composite microspheres with superior photocatalytic properties, Applied Catalysis B: Environmental, 104 (2011) 12–20. https://doi.org/10.1016/j.apcatb.2011.03.008
[6] C. Hui, C. Shen, J. Tian, L. Bao, H. Ding, C. Li, Y. Tian, X. Shi, H.J. Gao, Core-shell Fe3O4@SiO2 nanoparticles synthesized with well-dispersed hydrophilic Fe3O4 seeds, Nanoscale, 3 (2011) 701–705. https://doi.org/10.1039/C0NR00497A
[7] M.A.Willard, L.K. Kurihara, E.E. Carpenter, S. Calvin, V.G. Harris, Chemically prepared magnetic nanoparticles, International Materials Reviews, 49 (2004) 125-170. https://doi.org/10.1179/095066004225021882
[8] Q.A. Pankhurst, J. Connolly, S.K. Jones, J. Dobson, Applications of magnetic nanoparticles in biomedicine, Journal of Physics D: Applied Physics, 36 (2003) R167-R181. https://doi.org/10.1088/0022-3727/36/13/201
[9] S.L. Tie, H.C. Lee, Y.S. Bae, M.B. Kim, K. Lee, C.H. Lee, Monodisperse Fe3O4/Fe@SiO2 core/shell nanoparticles with enhanced magnetic property, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 293 (2007) 278–285. https://doi.org/10.1016/j.colsurfa.2006.07.044
[10] J.L.Snoek, New Development in Ferromagnetic Materials. Elsevier, New York, 1947.
[11] J. Smit, H. P. J. Wijn, Ferrites, Philips Technical Library, Netherlands, 1959.
[12] C.C.H. Lo, A.P. Ring, J.E. Snyder, D.C. Jiles, Improvement of magnetomechanical properties of cobalt ferrite by magnetic annealing, IEEE Transactions on Magnetics,41 (2005) 3676-3678. https://doi.org/10.1109/TMAG.2005.854790
[13] S.H. Song, C.C.H. Lo, S.J. Lee, Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite, Journal of Applied Physics,101 (2007) 09c517.
[14] O.F. Caltun, G.S.N. Rao, K.H. Rao, B. Parvatheeswara Rao, Cheol Gi Kim, Chong-Oh Kim, I. Dumitru, N. Lupu, H. Chiriac, High magnetostrictive cobalt ferrite for sensor application, Sensor Letters, 5 (2007) 1-3. https://doi.org/10.1166/sl.2007.027
[15] O.F. Caltun, G.S.N. Rao, K.H. Rao, B. Parvatheeswara Rao, H.L.Wamocha, H. Hamdeh, Influence of silicon and cobalt substitutions on magnetostriction coefficient of cobalt ferrite, Hyperfine interactions, 184 (2008) 179-184. https://doi.org/10.1007/s10751-008-9786-6
[16] S. Santra, R. Tapec, N. Theodoropoulou, J. Dobson, A. Hebard, W.H. Tan, Synthesis and Characterization of Silica-Coated Iron Oxide Nanoparticles in Microemulsion:  The Effect of Nonionic Surfactants, Langmuir, 17 (2001) 2900–2906. https://doi.org/10.1021/la0008636
[17] W. Stober, A. Fink, E. Bohn, Controlled growth of monodisperse silica spheres in the micron size range, Journal of Colloid and Interface Science, 26 (1968) 62-69. https://doi.org/10.1016/0021-9797(68)90272-5
[18] Mohamed Abbas, B. Parvatheeswara Rao, Venu Reddy, CheolGi Kim, Fe3O4/TiO2 core/shell nanocubes: Single-batch surfactantless synthesis, characterization and efficient catalysts for methylene blue degradation, Ceramics International, 40 (2014) 11177–11186. https://doi.org/10.1016/j.ceramint.2014.03.148
[19] Mohamed Abbas, B. Parvatheeswara Rao, Md. Nazrul Islam, S.M. Naga, Migaku Takahashi, CheolGi Kim, Highly stable- silica encapsulating magnetite nanoparticles (Fe3O4/SiO2) synthesized using single surfactantless- polyol process, Ceramics International, 40 (2014) 1379–1385. https://doi.org/10.1016/j.ceramint.2013.07.019
[20] M. Abbas, B. Parvatheeswara Rao, S.M.Naga, Migaku Takahashi, CheolGi Kim, Synthesis of high magnetization hydrophilic magnetite (Fe3O4) nanoparticles in single reaction—Surfactantless polyol process, Ceramics International, 39 (2013) 7605–7611. https://doi.org/10.1016/j.ceramint.2013.03.015
[21] Wei-Chih Hsu, S.C. Chen, P.C. Kuo, C.T. Lie, W.S. Tsai, Preparation of NiCuZn ferrite nanoparticles from chemical co-precipitation method and the magnetic properties after sintering, Materials Science and Engineering: B, 111 (2004) 142–149. https://doi.org/10.1016/j.mseb.2004.04.009
[22] Anjali Verma, Ratnamala Chatterjee, Effect of zinc concentration on the structural, electrical and magnetic properties of mixed Mn–Zn and Ni–Zn ferrites synthesized by the citrate precursor technique, Journal of Magnetism and Magnetic Materials, 306 (2006) 313– 320. https://doi.org/10.1016/j.jmmm.2006.03.033
[23] T. Slatineanu, A.R. Iordan, M.N. Palamaru, O.F. Caltun, V. Gafton, L. Leontie, Synthesis and characterization of nanocrystalline Zn ferrites substituted with Ni, Materials Research Bulletin, 46 (2011) 1455–1460. https://doi.org/10.1016/j.materresbull.2011.05.002
[24] K.C. Patil, Advanced ceramics: Combustion synthesis and properties, Bulletin of Materials Science, 16 (1993) 533-542. https://doi.org/10.1007/BF02757654
[25] Mohamed Abbas, Md.Nazrul Islam, B. Parvatheeswara Rao, K.E. AbouAitah, Cheol Gi Kim, Facile approach for synthesis of high moment Fe/ferrite and FeCo/ferrite core/shell nanostructures, Materials Letters,139 (2015)161–164. https://doi.org/10.1016/j.matlet.2014.10.078
[26] Mohamed Abbas, Sri Ramulu Torati, B. Parvatheeswara Rao, M.O. Abdel-Hamed, CheolGi Kim, Size controlled sonochemical synthesis of highly crystalline superparamagnetic Mn–Zn ferrite nanoparticles in aqueous medium, Journal of Alloys and Compounds,644 (2015) 774–782. https://doi.org/10.1016/j.jallcom.2015.05.101
[27] B. Parvatheeswara Rao, Chong-Oh Kim, CheolGi Kim, I. Dumitru, L. Spinu, O. F. Caltun, Structural and magnetic characterizations of coprecipitated Ni–Zn and Mn–Zn ferrite nanoparticles, IEEE Transactions on Magnetics, 42 (2006) 2858- 2860. https://doi.org/10.1109/TMAG.2006.879901
[28] Mohamed Abbas, B. Parvatheeswara Rao, Cheol Gi Kim, Shape and size-controlled synthesis of Ni Zn ferrite nanoparticles by two different routes, Materials Chemistry and Physics, 147 (2014) 443-451. https://doi.org/10.1016/j.matchemphys.2014.05.013
[29] C.G. Koops, On the dispersion of resistivity and dielectric constant of some semiconductors at audio frequencies, Physical Review, 83 (1951) 121-125. https://doi.org/10.1103/PhysRev.83.121
[30] G.C. Jain, B.K. Das, N.C. Goel, Grain growth during sintering of manganese-zinc-iron ferrites, Indian Journal of Pure & Applied Physics,14 (1976) 87-92.
[31] A. Globus, P. Duplex, Separation of susceptibility mechanisms for ferrites of low anisotropy, IEEE Transactions on Magnetics,MAG-2 (1966) 441-445. https://doi.org/10.1109/TMAG.1966.1065867
[32] B. Parvatheeswara Rao, P.S.V. Subba Rao, A. Lakshman, K.H. Rao, Influence of sintering conditions on the microstructural and electrical properties of Ni-Zn ferrites, Journal of the Magnetics Society of Japan, 22 (1998) (S1) 83-85.
[33] B. Parvatheeswara Rao, K.H. Rao, Effect of sintering conditions on resistivity and dielectric properties of Ni-Zn ferrites, Journal of Materials Science, 32 (1997) 6049-6054. https://doi.org/10.1023/A:1018683615616
[34] S. Dasgupta, J. Das, J. Eckert, I. Manna, Influence of environment and grain size on magnetic properties of nanocrystalline Mn–Zn ferrite, Journal of Magnetism and Magnetic Materials, 306 (2006) 9-15. https://doi.org/10.1016/j.jmmm.2006.02.266
[35] K. Praveena, K.Sadhana, S.Bharadwaj, S.R.Murthy, Development of nanocrystalline Mn–Zn ferrites for high frequency transformer applications, Journal of Magnetism and Magnetic Materials, 321 (2009) 2433-2437. https://doi.org/10.1016/j.jmmm.2009.02.138
[36] S. Dasgupta, K.B. Kim, J. Ellrich, J. Eckert, I. Manna, Mechano-chemical synthesis and characterization of microstructure and magnetic properties of nanocrystalline Mn1−xZnxFe2O4, Journal of Alloys and Compounds, 424 (2006) 13-20. https://doi.org/10.1016/j.jallcom.2005.12.078
[37] B. Jeyadevan, K. Tohji, K. Nakatsuka, A. Narayanasamy, Irregular distribution of metal ions in ferrites prepared by co-precipitation technique structure analysis of Mn–Zn ferrite using extended X-ray absorption fine structure, Journal of Magnetism and Magnetic Materials, 217 (2000) 99-105. https://doi.org/10.1016/S0304-8853(00)00108-6
[38] Z. Yue, Ji Zhou, L. Li, H. Zhang, Z. Gui, Synthesis of nanocrystalline NiCuZn ferrite powders by sol–gel auto-combustion method, Journal of Magnetism and Magnetic Materials, 208 (2000) 55-60. https://doi.org/10.1016/S0304-8853(99)00566-1
[39] N. Rezlescu, L. Rezlescu, P.D. Popa, E. Rezlescu, Influence of additives on the properties of a Ni–Zn ferrite with low Curie point, Journal of Magnetism and Magnetic Materials, 215-216 (2000) 194-196. https://doi.org/10.1016/S0304-8853(00)00114-1
[40] V.T. Zaspalis, V. Tsakaloudi, M. Kolenbrander, The effect of dopants on the incremental permeability of MnZn-ferrites, Journal of Magnetism and Magnetic Materials, 313 (2007) 29-36. https://doi.org/10.1016/j.jmmm.2006.11.210
[41] H. L. Ge, Z. J. Peng, C. B. Wang, Z. Q. Fu, Effect of Al3+ doping on magnetic and dielectric properties of Ni–Zn ferrites by “one-step synthesis”, International Journal of Modern Physics, B 25 (2011) 3881–3892. https://doi.org/10.1142/S0217979211101703
[42] Jozef Slama, A. Gruskova, M. Usakova, E. Usak, R. Dosoudil, Contribution to analysis of Cu-substituted NiZn ferrites, Journal of Magnetism and Magnetic Materials, 321 (2009) 3346-3351. https://doi.org/10.1016/j.jmmm.2009.06.024
[43] A.A. Sattar, H.M. El-Sayed, K.M. El-Shokrofy, M.M. El-Tabey, Effect of Manganese Substitution on the Magnetic Properties of Nickel-Zinc Ferrite, Journal of Materials Engineering and Performance, 14 (2005) 99-103. https://doi.org/10.1361/10599490522185
[44] H. Zhong and H. Zhang, Effects of different sintering temperature and Mn content on magnetic properties of NiZn ferrites, Journal of Magnetism and Magnetic Materials, 283 (2004) 247–250. https://doi.org/10.1016/j.jmmm.2004.05.029
[45] B. V. Bhise, M. B. Dongare, S. A. Patil, S. R. Sawant, X-ray infrared and magnetization studies on Mn substituted Ni-Zn ferrites, Journal of Materials Science Letters, 10 (1991) 922-924. https://doi.org/10.1007/BF00724783
[46] C. Venkataraju, G.Sathishkumar, K.Sivakumar, Effect of cation distribution on the structural and magnetic properties of nickel substituted nanosized Mn–Zn ferrites prepared by co-precipitation method, Journal of Magnetism and Magnetic Materials, 322 (2010) 230-233. https://doi.org/10.1016/j.jmmm.2009.08.043
[47] B. Parvatheeswara Rao, Cheol Gi Kim, Effect of Nb2O5 additions on the power loss of NiZn ferrites, Journal of Materials Science, 42 (2007) 8433–8437. https://doi.org/10.1007/s10853-007-1789-1
[48] B. Parvatheeswara Rao, Chong-Oh Kim, CheolGi Kim, Influence of V2O5 additions on the permeability and power loss characteristics of Ni–Zn ferrites, Materials Letters, 61 (2007) 1601–1604. https://doi.org/10.1016/j.matlet.2006.07.191
[49] S.H. Chen, S.C. Chang, C.Y. Tsay, K.S. Liu, I.N. Lin, Improvement on magnetic power loss of MnZn-ferrite materials by V2O5 and Nb2O5 co-doping, Journal of the European Ceramic Society, 21 (2001) 1931-1935. https://doi.org/10.1016/S0955-2219(01)00145-5
[50] K. Sun, Z. Lan, Z. Yu, L. Li, H. Ji, Z. Xu, Effects of NiO addition on the structural, microstructural and electromagnetic properties of manganese–zinc ferrite, Materials Chemistry and Physics, 113 (2009) 797-802. https://doi.org/10.1016/j.matchemphys.2008.08.052
[51] R. Arulmurugan, B. Jeyadevan, G. Vaidyanathan, S. Sendhilna, Effect of zinc substitution on Co–Zn and Mn–Zn ferrite nanoparticles prepared by co-precipitation, Journal of Magnetism and Magnetic Materials, 288 (2005) 470-477. https://doi.org/10.1016/j.jmmm.2004.09.138
[52] A.R. Bueno, M.L. Gregori, M.C.S. N´obrega, Effect of Mn substitution on the microstructure and magnetic properties of Ni0.50xZn0.50xMn2xFe2O4 ferrite prepared by the citrate–nitrate precursor method, Materials Chemistry and Physics, 105 (2007) 229–233. https://doi.org/10.1016/j.matchemphys.2007.04.047
[53] B. Parvatheeswara Rao, K.H. Rao, Distribution of In3+ ions in indium-substituted Ni–Zn–Ti ferrites, Journal of Magnetism and Magnetic Materials, 292 (2005) 44–48. https://doi.org/10.1016/j.jmmm.2004.10.093
[54] S. Ramesh, B.ChandraSekhar, P.S.V.SubbaRao, B.ParvatheeswaraRao, Microstructural and magnetic behavior of mixed Ni–Zn–Co and Ni–Zn–Mn ferrites, Ceramics International 40(2014)8729–8735. https://doi.org/10.1016/j.ceramint.2014.01.092
[55] S. Ramesh, Effect of Mn/Co Substitutions on the properties of nano and bulk Ni-Zn ferrites Ph.D. thesis, Andhra University, India, 2014.
[56] R.F. Pearson, The Magnetocrystalline Anisotropy of Cobalt-Substituted Manganese Ferrite, Proceedings of the Physical Society, 74 (1959) 505-512.
[57] R.D.Greenough, E.W.Lee, The magnetostriction of cobalt-manganese ferrite, Journal of Physics D: Applied Physics, 3(1970) 1595-1604. https://doi.org/10.1088/0022-3727/3/11/306
[58] J.C. Slonczewsky, Theory of Magnetostriction in Cobalt-Manganese Ferrite, Physical Review, 122 (1961) 1367-1372. https://doi.org/10.1103/PhysRev.122.1367
[59] G.S.N. Rao, B. Parvatheeswara Rao, O.F. Caltun, Cation Distribution of Cobalt-manganese Ferrite for Torque Sensor Applications, Materials Today: Proceedings, 2 (2015) 2491 – 2495. https://doi.org/10.1016/j.matpr.2015.07.192
[60] Y. Chen, J.E. Snyder, K.W. Dennis, R.W. McCallum, D.C. Jiles, Temperature dependence of the magnetomechanical effect in metal-bonded cobalt ferrite composites under torsional strain, Journal of Applied Physics, 87 (2000) 5798. https://doi.org/10.1063/1.372526
[61] G.S.N. Rao, O.F. Caltun, K.H Rao, P.S.V. Subba Rao, B. Parvatheeswara Rao, Improved magnetostrictive properties of Co–Mn ferrites for automobile torque sensor applications, Journal of Magnetism and Magnetic Materials, 341(2013) 60-64. https://doi.org/10.1016/j.jmmm.2013.04.039
[62] C.C.H. Lo, Compositional dependence of the magnetomechanical effect in substituted cobalt ferrite for magnetoelastic stress sensors, IEEE Transactions on Magnetics, 43 (2007)2367-2369. https://doi.org/10.1109/TMAG.2007.892536
[63] N. Wiriyal, A. Bootchanont, S. Maensiri, E. Swatsitang, X-ray absorption fine structure analysis of Mn1−xCoxFe2O4 nanoparticles prepared by hydrothermal method, Japanese Journal of Applied Physics, 53 (2014) 06JF09.
[64] O.F. Caltun, G.S.N. Rao, K.H. Rao, B. Parvatheeswara Rao, Ioan Dumitru, Chong-Oh Kim, Cheol Gi Kim, The influence of Mn doping level on magnetostriction coefficient of cobalt ferrite, Journal of Magnetism and Magnetic Materials, 316 (2007) e618-e620. https://doi.org/10.1016/j.jmmm.2007.03.045
[65] S.D. Bhame, P.A. Joy, Enhanced magnetostrictive properties of Mn substituted cobalt ferrite Co1.2Fe1.8O4, Journal of Applied Physics, 99 (2006) 073901. https://doi.org/10.1063/1.2183356
[66] S.D. Bhame, P.A. Joy, Tuning of the magnetostrictive properties of CoFe2O4 by Mn substitution for Co, Journal of Applied Physics, 100 (2006) 113911. https://doi.org/10.1063/1.2401648
[67] G.V. Duong, R.S. Turtelli, N. Hanh, D.V. Linh, M. Reissner, H. Michor, J. Fidler, G. Wiesinger, R. Grössinger, Magnetic properties of nanocrystalline Co1−xZnxFe2O4 prepared by forced hydrolysis method, Journal of Magnetism and Magnetic Materials, 307(2006) 313-317. https://doi.org/10.1016/j.jmmm.2006.03.072
[68] K. Mohaideen, P.A. Joy, High magnetostriction and coupling coefficient for sintered cobalt ferrite derived from superparamagnetic nanoparticles, Applied Physics Letters, 101 (2012) 72405. https://doi.org/10.1063/1.4745922
[69] K. Mohaideen, P.A. Joy, Enhancement in the Magnetostriction of Sintered Cobalt Ferrite by Making Self-Composites from Nanocrystalline and Bulk Powders, Applied Materials and Interfaces, 4 (2012) 6421-6425. https://doi.org/10.1021/am302053q
[70] J. Wang, X. Gao, C. Yuan, J. Li, X. Bao, Magnetostriction properties of oriented polycrystalline CoFe2O4, Journal of Magnetism and Magnetic Materials,401(2016) 662–666. https://doi.org/10.1016/j.jmmm.2015.10.073
[71] Shyam K. Gore, Santosh S. Jadhav, Vijaykumar V. Jadhav, S. M. Patange, Mu. Naushad, Rajaram S. Mane, Kwang Ho Kim, The structural and magnetic properties of dual phase cobalt ferrite, Scientific Reports, 7 (2017) 2524. https://doi.org/10.1038/s41598-017-02784-z
[72] B. Chandra Sekhar , G.S.N. Rao,.O.F. Caltun, B. Dhanalakshmi, B. Parvatheeswara Rao, P.S.V. Subba Rao, Magnetic and magnetostrictive properties of Cu substituted Co-ferrites, Journal of Magnetism and Magnetic Materials,398 (2016) 59-63. https://doi.org/10.1016/j.jmmm.2015.09.028
[73] R. W. McCallum, K. W. Dennis, D. C.Jiles, J. E. Snyder, Y. H. Chen, Composite magnetostrictive materials for advanced automotive magnetomechanical sensors, Low Temperature Physics, 27 (2001) 266-274. https://doi.org/10.1063/1.1365598
[74] Y.X. Zheng, Q.Q. Cao, C.L. Zhang, H.C. Xuan, L.Y. Wang, D.H. Wang, Y.W. Du, Study of uniaxial magnetism and enhanced magnetostriction in magnetic-annealed polycrystalline CoFe2O4, Journal of Applied Physics,110 (2011) 043908. https://doi.org/10.1063/1.3624661
[75] Q.S. Tang, D.S. Zhang, X.M. Cong, M.l. Wan, L.Q. Jin, Using thermal energy produced by irradiation of Mn–Zn ferrite magnetic nanoparticles (MZF-NPs) for heat-inducible gene expression, Biomaterials, 29 (2008) 2673-2679. https://doi.org/10.1016/j.biomaterials.2008.01.038
[76] Mohamed Abbas, Md. NazrulIslam, B. Parvatheeswara Rao, T. Ogawa, Migaku Takahashi, Cheol Gi Kim, One-pot synthesis of high magnetization air-stable FeCo nanoparticles by modified polyol method, Materials Letters, 91(2013) 326–329. https://doi.org/10.1016/j.matlet.2012.10.019
[77] F. Fievet, J.P. Lagier, M. Figlarz, Preparing Monodisperse Metal Powders in Micrometer and Submicrometer Sizes by the Polyol Process, Materials Research Society Bulletin, 14 (1989) 29-34.
[78] F. Dang, N. Enomoto, J. Hojo, K. Enpuku, Sonochemical synthesis of monodispersed magnetite nanoparticles by using an ethanol–water mixed solvent, Ultrasonics Sonochemistry, 16 (2009) 649-654. https://doi.org/10.1016/j.ultsonch.2008.11.003
[79] J.H. Bang, K.S. Suslick, Applications of ultrasound to the synthesis of nanostructured materials, Advanced Materials, 22 (2010) 1039-1059. https://doi.org/10.1002/adma.200904093
[80] H. Wang, D. Udukala, T. Samarakoon, M. Basel, M. Kalita, G. Abayaweera, Nanoplatforms for highly sensitive fluorescence detection of cancer-related proteases, Photochemical and Photobiological Sciences, 13 (2014) 231–240. https://doi.org/10.1039/c3pp50260k