References
- V.M. Khot, A.B. Salunke, M.R. Phadatare and S.H. Pawar, Formation, microstructure and magnetic properties of nanocrystalline MgFe2O4. Mater. Chem. Phys. 132 (2012), pp. 782–787. doi:10.1016/j.matchemphys.2011.12.012.
- S. Maensiri, M. Sangmanee and A. Wiengmoon, Magnesium ferrite (MgFe2O4) nanostructures fabricated by electrospinning. Nanoscale Res. Lett. 4 (2009), pp. 221–228. doi:10.1007/s11671-008-9229-y.
- V. Šepelák, D. Baabe, D. Mienert, F.J. Litterst and K.D. Becker, Enhanced magnetisation in nanocrystalline high-energy milled MgFe2O4. Scripta Mater. 48 (2003), pp. 961–966. doi:10.1016/S1359-6462(02)00600-0.
- P.M.G. Nambissan, Defects characterization in nanomaterials through positron annihilation spectroscopy, in Nanotechnology: Synthesis and Characterization (Volume 2), S. Sinha, N.K. Navani and J.N. Govil, eds., Studium Press LLC, Houston, 2013. pp. 455–491. Available at www.studiumpress.in/nanotechnology-vol-2-synthesis-and-characterization.html.
- A. Dupasquier and A.P. Mills, Positron spectroscopy of solids – Proceedings of the 125th International School of Physics ‘Enrico Fermi’, July 6–16, 1993, Lake Como, Villa Monastero, Italy. IOS Press, Amsterdam, The Netherlands, 1995, pp. 1–780. Available at www.iospress.nl/book/positron-spectroscopy-of-solids/
- R. Krause-Rehberg and H.S. Leipner, Positron Annihilation in Semiconductors – Defect Studies, Springer, Berlin, 1999, pp. 1–379. Available at https://www.springer.com/in/book/%209783540643715.
- H. Klym, A. Ingram, O. Shpotyuk, J. Filipecki and I. Hadzaman, Extended positron-trapping defects in insulating MgAl2O4 spinel-type ceramics. Phys. Stat. Solno. (C4) (2007), pp. 715–718. doi:10.1002/pssc.200673735.
- O. Shpotyuk, A. Ingram, H. Klyma, M. Vakiv, I. Hadzamana and J. Filipecki, PAL spectroscopy in application to humidity-sensitive MgAl2O4 ceramics. J. Eur. Ceram. Soc. 25 (2005), pp. 2981–2984. doi:10.1016/j.jeurceramsoc.2005.03.174.
- K.B. Modi, N.H. Vasoya, V.K. Lakhani, T.K. Pathak and P.M.G. Nambissan, Crystal defects and cation redistribution study on nanocrystalline cobalt-ferri-chromites by positron annihilation spectroscopy. Internat. J. Spectro 2013 (2013), pp. 272846 ( 11p). doi:10.1155/2013/272846.
- R.M. Thankachan, J. Cyriac, B. Raneesh, N. Kalarikkal, D. Sanyal and P.M.G. Nambissan, Cr3+-substitution induced structural reconfigurations in the nanocrystalline spinel compound ZnFe2O4 as revealed from x-ray diffraction, positron annihilation and mössbauer spectroscopic studies. RSC Adv. 5 (2015), pp. 64966–64975. doi:10.1039/C5RA04516A.
- J.V. Olsen, P. Kirkegaard, N.J. Pedersen and M. Eldrup, PALSfit: a new program for the evaluation of positron lifetime spectra. Phys. Status Solidi. C 4 (2007), pp. 4004–4006. doi:10.1002/pssc.200675868.
- A. Chatterjee, K. Ramachandran, S. Singh, S.S. Pande and M.D. Ghodgaonkar, Linux-based advanced multi parameter software. Proceed. DAE Symp. Nucl. Phys. 45 (2002), pp. 145–146. Available at www.tifr.res.in/~pell/lamps.html.
- M. Chakrabarti, D. Sanyal and A. Chakrabarti, Preparation of Zn(1−x)CdxFe2O4 (x = 0.0, 0.1, 0.3, 0.5, 0.7 and 1.0) ferrite samples and their characterization by Mössbauer and positron annihilation techniques. J. Phys.: Condens. Matter. 19 (2007), pp. 236210 ( 11p). doi:10.1088/0953-8984/19/23/236210.
- E. von Meerwall, A least-squares spectral curve fitting routine for strongly overlapping Lorentzians or Gaussians. Comp. Phys. Commun. 9 (1975), pp. 117–128. doi:10.1016/0010-4655(75)90028-4.
- A.L. Patterson, The Scherrer formula for X-Ray particle size determination. Phys. Rev. 56 (1939), pp. 978–982. doi:10.1103/PhysRev.56.978.
- B.D. Cullity, Elements of X-ray diffraction, Addison-Wesley Publishing Company, Inc., Philippines, 1978, pp. 1–284. www.scribd.com/doc/104415520/.
- P. Manuel Diehm, P. Ágoston and K. Albe, Size-dependent lattice expansion in nanoparticles: reality or anomaly? ChemPhysChem ( Special Issue: Nanomaterials) 13 (2012), pp. 2443–2454. doi:10.1002/cphc.201200257.
- N. Kamarulzaman, N.F. Chayed, N. Badar, M.F. Kasim, D.T. Mustaffa, K. Elong, R. Rusdi, T. Oikawa and H. Furukawa, Band Gap Narrowing of 2-D ultra-thin MgO graphene-like sheets. ECS J. Solid State Sci. Technol. 5 (2016), pp. Q3038–Q3045. doi:10.1149/2.0081611jss.
- S. Adachi, Handbook on Physical Properties of Semiconductors, Kluwer Academic Publisher, New York, 2004, pp. 1–21.
- S.S. Nair, M. Mathews and M.R. Anantharaman, Evidence for blueshift by weak exciton confinement and tuning of bandgap in superparamagnetic nanocomposites. Chem. Phys. Lett. 406 (2005), pp. 398–403. doi:10.1016/j.cplett.2005.02.107.
- S.I. Srikrishna Ramya and C.K. Mahadevan, Effect of calcination on the electrical properties and quantum confinement of Fe2O3 nanoparticles. Internat. J. Res. Engg. Tech. 3 (2014), pp. 570–581. doi:10.15623/ijret.2014.0303107.
- N.M. Deraz and O.H. Abd-Elkader, Investigation of magnesium ferrite spinel solid solution with iron-rich composition. Int. J. Electrochem. Sci. 8 (2013), pp. 9071–9081. http://www.electrochemsci.org/papers/vol8/80709071.
- J. Tauc, Optical properties and electronic structure of amorphous Ge and Si. Mater. Res. Bull. 3 (1968), pp. 37–46. doi:10.1016/0025-5408(68)90023-8.
- J. Tauc, Amorphous and Liquid Semiconductors, Plenum, New York, 1974, pp. 159–220. doi: 10.1007/978-1-4615-8705-7_4
- A. Köferstein, T. Walther, D. Hesse and S.G. Ebbinghaus, Preparation and characterization of nanosized magnesium ferrite powders by a starch-gel process and corresponding ceramics. J Mater. Sci. 48 (2013), pp. 6509–6518. doi:10.1007/s10853-013-7447-x.
- S. Kar, S. Biswas, S. Chaudhuri and P.M.G. Nambissan, Finite-size effects on band structure of CdS nanocrystallites studied by positron annihilation. Phys. Rev. B 72 (2005), pp. 075338. ( 7pp). doi:10.1103/PhysRevB.72.075338.
- A. Das, A.C. Mandal, S. Roy and P.M.G. Nambissan, Positron annihilation studies of defects and fine size effects in nanocrystalline nickel oxide. J. Experi. Nanosci. 10 (2015), pp. 622–639. http://www.tandfonline.com/loi/tjen20. doi: 10.1080/17458080.2013.860490
- S. Perumbilavil, K. Sridharan, A.R. Abraham, H.P. Janardhanan, N. Kalarikkal and R. Philip, Nonlinear transmittance and optical power limiting in magnesium ferrite nanoparticles: effects of laser pulse width and particle size. RSC Adv. 6 (2016), pp. 106754–106761. https://pubs.rsc.org/en/content/articlelanding/2016/ra/c6ra15788b. doi: 10.1039/C6RA15788B
- A. Pradeep, P. Priyadharsini and G. Chandrasekaran, Sol - gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study. J. Mag. Mag. Mater. 320 (2008), pp. 2774–2779. doi:10.1016/j.jmmm.2008.06.012.
- A. Uedono, K. Shimoyama, M. Kiyohara and K. Yamabe, Defects in CeO2 /SrTiO3 fabricated by automatic feeding epitaxy probed using positron annihilation. J. Appl. Phys. 94 (2003), pp. 5193–5198. doi:10.1063/1.1606112.
- S. Chakraverty, S. Mitra, K. Mandal, P.M.G. Nambissan and S. Chattopadhyay, Positron annihilation studies of some anomalous features of NiFe2O4 nanocrystals grown in SiO2. Phys. Rev. B 71 (2005), pp. 024115. ( 8p). doi:10.1103/PhysRevB.71.024115.
- P.M.G. Nambissan, O. Mondal, S. Chakrabarty and M. Pal, Ni-substitution induced inversion in ZnFe2O4 seen by positron annihilation. Mater. Scie. Forum 733 (2013), pp. 219–223. doi:10.4028/www.scientific.net/MSF.733.219.
- P.M.G. Nambissan, C. Upadhyay and H.C. Verma, Positron lifetime spectroscopic studies of nanocrystalline ZnFe2O4. J. Appl. Phys. 93 (2003), pp. 6320–6326. doi:10.1063/1.1569973.
- J. Smit and H.P.J. Wijn, Ferrites – Physical Properties of Ferrimagnetic Oxides in Relation to Their Technical Applications, Eindhoven, Holland: N.V. Philip’s Gloeilampenfabrieken (1959) 136–175. Available from https://pubs.acs.org/doi/abs/10.1021/ed037p380.3
- S. Chakrabarti, S. Chaudhuri and P.M.G. Nambissan, Positron annihilation lifetime changes across the structural phase transition in nanocrystalline Fe2O3. Phys. Rev. B 71 (2005), pp. 064105. doi:10.1103/PhysRevB.71.064105.
- S. Bandyopadhyay, A. Roy, D. Das, S.S. Ghugre and J. Ghose, Investigation of nanocrystalline CoFe2O4 by positron annihilation lifetime spectroscopy. Philos. Mag. 83 (2003), pp. 765–773. doi:10.1080/0141861021000042271.
- J. Cyriac, R.M. Thankachan, B. Raneesh, P.M.G. Nambissan, D. Sanyal and N. Kalarikkal, Positron annihilation spectroscopic studies of Mn substitution-induced cubic to tetragonal transformation in ZnFe2–xMnxO4 (x = 0.0–2.0) spinel nanocrystallites. Philos. Mag. 95 (2015), pp. 4000–4022. doi:10.1080/14786435.2015.1110631.
- R.G. Burns, Mineralogical Applications of Crystal Field Theory, Cambridge Univ. Press, Cambridge, 1993, pp. 1–551. doi: 10.1017/CBO9780511524899
- R.D. Shannon, Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst. A 32 (1976), pp. 751–767. doi:10.1107/S0567739476001551.
- R.M. de la Cruz, R. Pareja, A. Segura, V. Mufioz and A. Chevyll, Temperature effects on the positron annihilation characteristics in III-VI layered semiconductors. J. Phys: Condens. Matter. 5 (1993), pp. 971–976. http://iopscience.iop.org/0953-8984/5/7/024.
- R.W. Siegel, Positron annihilation spectroscopy. Ann. Rev. Mater. Sci. 10 (1980), pp. 393–425. doi:10.1146/annurev.ms.10.080180.002141.
- E. Boronski and R.M. Nieminen, Electron-positron density-functional theory. Phys. Rev. B 34 (1986), pp. 3820–3831. doi:10.1103/PhysRevB.34.3820.
- O. Shpotyuk, A. Ingram, Z. Bujňáková, P. Baláž and Y. Shpotyuk, Probing sub-atomistic free-volume imperfections in dry-milled nanoarsenicals with PAL spectroscopy. Nanoscale Res. Lett. 11 (2016), pp. 10-1–10-7. doi:10.1186/s11671-016-1228-9 doi: 10.1186/s11671-016-1318-8
- P. Asoka-Kumar, M. Alatalo, V.J. Ghosh, A.C. Kruseman, B. Nielsen and K.G. Lynn, Increased elemental specificity of positron annihilation spectra. Phys. Rev. Lett. 77 (1996), pp. 2097–2100. doi:10.1103/PhysRevLett.77.2097.
- Y. Nagai, T. Nonaka, M. Hasegawa, Y. Kobayashi, C.L. Wang, W. Zheng and C. Zhang, Direct evidence of positron trapping at polar groups in a polymer-blend system. Phys. Rev. B 60 (1999), pp. 11863–11866. doi:10.1103/PhysRevB.60.11863.
- R.K. Panda, R. Muduli, G. Jayarao, D. Sanyal and D. Behera, Effect of Cr3+ substitution on electric and magnetic properties of cobalt ferrite nanoparticles. J Alloys & Compd. 669 (2016), pp. 19–28. doi:10.1016/j.jallcom.2016.01.256.