Nanometric Particle Size And Phase Controlled Synthesis And Characterization Of γ-fe2o3 Or (α + γ)-fe2o3 By A Modified Sol-gel Method

Fe2O3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and Mössbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. Maghemite-hematite phase transition and hematite Néel transition were observed near 700 K and 1015 K, respectively. Magnetization of the particles increases consistently with the increase in the amount of PVA used in the synthesis. Mössbauer spectra were adjusted with a hematite sextet and maghemite distribution for A6, A12, and A24 and with maghemite distribution for A18, in agreement with XRD results. © 2013 AIP Publishing LLC.11410Xu, P., Zeng, G.M., Huang, D.L., Feng, C.L., Hu, S., Zhao, M.H., Lai, C., Liu, Z.F., (2012) Sci. Total Environ., 424, pp. 1-10. , 10.1016/j.scitotenv.2012.02.023Rajabi, F., Karimi, N., Saidi, M.R., Primo, A., Varma, R.S., Luque, R., (2012) Adv. Synth. Catal., 354, pp. 1707-1711. , 10.1002/adsc.201100630Kitamuraa, H., Zhaob, L., Hangc, B.T., Okadab, S., Yamaki, J.-I., (2012) J. Power Sources, 208, pp. 391-396. , 10.1016/j.jpowsour.2012.02.051Figuerola, A., Di Corato, R., Manna, L., Pellegrino, T., (2010) Pharmacol. Res., 62, pp. 126-143. , 10.1016/j.phrs.2009.12.012Yang, H.-M., Oh, B.C., Kim, J.H., Ahn, T., Nam, H.-S., Park, C.W., Kim, J.-D., (2011) Colloids Surf., A, 391, pp. 208-215. , 10.1016/j.colsurfa.2011.04.032Xu, H., Aguilar, Z.P., Yang, L., Kuang, M., Duan, H., Xiong, Y., Wei, H., Wang, A., (2011) Biomaterials, 32, pp. 9758-9765. , 10.1016/j.biomaterials.2011.08.076Mahmoudi, M., Sant, S., Wang, B., Laurent, S., Sen, T., (2011) Adv. Drug Delivery Rev., 63, pp. 24-46. , 10.1016/j.addr.2010.05.006Jolivet, J.-P., Cassaignon, S., Chanéac, C., Chiche, D., Durupthy, O., Portehault, D., (2010) C. R. Chim., 13, pp. 40-51. , 10.1016/j.crci.2009.09.012Yang, S., Jang, Y.-H., Kim, C.H., Hwang, C., Lee, J., Chae, S., Jung, S., Choi, M., (2010) Powder Technol., 197, pp. 170-176. , 10.1016/j.powtec.2009.09.011Wu, Y., Wang, X., (2011) Mater. Lett., 65, pp. 2062-2065. , 10.1016/j.matlet.2011.04.004Fernandes, D.M., Hechenleitner, A.A.W., Silva, M.F., Lima, M.K., Bittencourt, P.R.S., Silva, R., Melo, M.A.C., Pineda, E.A.G., (2009) Mater. Chem. Phys., 118, pp. 447-452. , 10.1016/j.matchemphys.2009.08.016Han, L.-H., Liu, H., Wei, Y., (2011) Powder Technol., 207, pp. 42-46. , 10.1016/j.powtec.2010.10.008Chen, L., Lin, Z., Zhao, C., Zheng, Y., Zhou, Y., Peng, H., (2011) J. Alloy Compd., 509, pp. 1-L5. , 10.1016/j.jallcom.2010.08.130Hassanjani-Roshan, A., Vaezi, M.R., Shokuhfar, A., Rajabali, Z., (2011) Particuology, 9, pp. 95-99. , 10.1016/j.partic.2010.05.013Khaleel, A., Al-Marzouqi, A., (2012) Mater. Lett., 68, pp. 385-387. , 10.1016/j.matlet.2011.11.002Komarneni, S., Hu, W., Noh, Y.D., Orden, A.V., Feng, S., Wei, C., Pang, H., Katsuki, H., (2012) Ceram. Int., 38, pp. 2563-2568. , 10.1016/j.ceramint.2011.11.027Fernandes, D.M., Silva, R., Hechenleitner, A.A.W., Radovanovic, E., Melo, M.A.C., Pineda, E.A.G., (2009) Mater. Chem. Phys., 115, pp. 110-115. , 10.1016/j.matchemphys.2008.11.038Rodriguez-Carvajal, J., (1993) Physica B, 192, pp. 55-69. , 10.1016/0921-4526(93)90108-ICornell, R.M., Sshwertmann, U., (2003) The Iron Oxides: Structures, Properties, Reactions, Occurrences and Uses, , (John Wiley Sons)Gotic, M., Music, S., Mössbauer, FT-IR and FE SEM investigation of iron oxides precipitated from FeSO4 solutions (2007) Journal of Molecular Structure, 834-836 (SPEC. ISS.), pp. 445-453. , DOI 10.1016/j.molstruc.2006.10.059, PII S0022286006009513Predoi, D., (2007) Dig. J. Nanomater. Biostruct., 2, pp. 169-173Namduri, H., Nasrazadani, S., (2008) Corros. Sci., 50, pp. 2493-2497. , 10.1016/j.corsci.2008.06.034Gulgun, M.A., Nguyen, M.H., Kriven, W.M., (1999) J. Am. Ceram. Soc., 82, pp. 556-560. , 10.1111/j.1151-2916.1999.tb01800.xFeng, J., Liu, T., Xu, Y., Zhao, J., He, Y., (2011) Ceram. Int., 37, pp. 1203-1207. , 10.1016/j.ceramint.2010.11.045Park, T.-J., Papaefthymiou, G.C., Moodenbaugh, A.R., Mao, Y., Wong, S.S., Synthesis and characterization of submicron single-crystalline Bi 2Fe4O9 cubes (2005) Journal of Materials Chemistry, 15 (21), pp. 2099-2105. , DOI 10.1039/b501552aLiu, T., Xu, Y., Zhao, J., (2010) J. Am. Ceram. Soc., 93, pp. 3637-3641. , 10.1111/j.1551-2916.2010.03945.xSarangi, P.P., Naik, B., Ghosh, N.N., (2009) Powder Technol., 192, pp. 245-249. , 10.1016/j.powtec.2009.01.002Sarangi, P.P., Naik, B.D., Vadera, S.R., Patra, M.K., Prakash, C., Ghosh, N.N., (2009) Mater. Technol.: Adv. Perform. Mater., 24, pp. 97-99. , 10.1179/175355509X387156Tauc, J., Grigorovici, R., Vancu, A., (1966) Phys. Status Solidi, 15, p. 627. , 10.1002/pssb.19660150224Martinez, F.L., Toledano-Luque, M., Gandia, J.J., Carabe, J., Bohne, W., Rohrich, J., Strub, E., Martil, I., Optical properties and structure of HfO2 thin films grown by high pressure reactive sputtering (2007) Journal of Physics D: Applied Physics, 40 (17), pp. 5256-5265. , DOI 10.1088/0022-3727/40/17/037, PII S0022372707493032, 037Rahman, M.M., Khan, S.B., Faisal, M., Asiri, A.M., Tariq, M.A., (2012) Electrochim. Acta, 75, pp. 164-170. , 10.1016/j.electacta.2012.04.093Gilbert, B., Frandsen, C., Maxey, E.R., Sherman, D.M., (2009) Phys. Rev. B, 79, p. 035108. , 10.1103/PhysRevB.79.035108Echigo, T., Aruguete, D.M., Murayamac, M., Hochella Jr., M.F., (2012) Geochim. Cosmochim. Acta, 90, pp. 149-162. , 10.1016/j.gca.2012.05.008Duret, A., Gratzel, M., Visible light-induced water oxidation on mesoscopic α-Fe 2O3 films made by ultrasonic spray pyrolysis (2005) Journal of Physical Chemistry B, 109 (36), pp. 17184-17191. , DOI 10.1021/jp044127cSouza, F.L., Lopes, K.P., Nascente, P.A.P., Leite, E.R., (2009) Sol. Energy Mater. Sol. Cells, 93, pp. 362-368. , 10.1016/j.solmat.2008.11.049De Oliveira, L.A.S., Sinnecker, J.P., Vieira, M.D., Penton-Madrigal, A., (2010) J. Appl. Phys., 107, pp. 09D907. , 10.1063/1.3362927Ennas, G., Marongiu, G., Musinu, A., Falqui, A., Ballirano, P., Caminiti, R., (1999) J. Mater. Res., 14, pp. 1570-1575. , 10.1557/JMR.1999.0210Wu, J., Mao, S., Ye, Z., Xie, Z., Zheng, L., (2010) ACS Appl. Mater. Interfaces, 2, pp. 1561-1564. , 10.1021/am1002052Phu, N.D., Ngo, D.T., Hoang, L.H., Luong, N.H., Chau, N., Hai, N.H., (2011) J. Phys. D: Appl. Phys., 44, p. 345002. , 10.1088/0022-3727/44/34/345002Nagar, H., Kulkarni, N.V., Karmakar, S., Sahoo, B., Banerjee, I., Chaudhari, P.S., Pasricha, R., Keune, W., (2008) Mater. Charact., 59, pp. 1215-1220. , 10.1016/j.matchar.2007.10.003Goulart, A.T., Filho D. F M, J., (1994) Hyperfine Interact., 83, pp. 451-455. , 10.1007/BF02074316Costa, G.M., Grave, E., Bowen, L.H., Vandenberghe, R.E., Bakker, P.M.A., (1994) Clay Clay Miner., 42, pp. 628-633. , 10.1346/CCMN.1994.042051

Geometric magnetic frustration in RE2O2S oxysulfides (RE = Sm, Eu and Gd)

RE2O2S oxysulfides (with RE = Sm, Eu and Gd) were prepared and characterized regarding their structural and magnetic properties. The compounds crystallized in the trigonal symmetry (space group P-3m/D33 d), with the lattice parameter varying linearly with the ionic radius of the RE cation. All these oxysulfides are magnetically frustrated and only the gadolinium sample showed magnetic order down to 3 K. The magnetic frustration is attributed to the spatial distribution of cations over the lattice, where the RE's magnetic moments occupy the sites forming a triangular plane lattice, perpendicular to the direction. This geometric magnetic frustration was firstly recognized for these oxysulfides

Mössbauer Study And Structural Characterization Of Uo2-gd2o3 Sintered Compounds

Samples of UO2 and up to 10 wt% of Gd2O3 were prepared by solid-state reaction under a reducing atmosphere, in a thermal path comprising ramps and dwell times in the temperature range of 900-1750 °C. The sintered material was analyzed by X-ray diffraction and 155Gd Mössbauer spectroscopy. The results showed that for samples annealed up to 900 °C, the gadolinium sesquioxide remained unreacted. However, when the temperature was increased to 1300 °C, a solid-state reaction took place forming mixed oxides. For the more severe sintering condition, at 1750 °C, gadolinia left urania partially unreacted producing a material consisting of two compositions, UO2 (with no dissolved gadolinium) and (U, Gd)O2. The proposed heating cycle provided pellets free from Gd2O3 phase and may be used by the nuclear fuel industry as a suitable sintering process. © 2008 Elsevier B.V. All rights reserved.37812529Assmann, H., Robin, J.P., (1983) Guidebook on Quality Control of Mixed Oxides and Gadolinium Bearing Fuels for Light Water Reactors, , IAEA-TECDOC-584, IAEA, Vienna p. 51Markl, H., Holzer, R., (1987) Kerntechnik, 50, p. 241T. Wada, K. Noro, K. Tsukui, in: Proceedings of the International Conference on Nuclear Fuel Performance, London, UK, 1973Manzel, R., Dörr, W.O., (1980) Am. Ceram. Soc. Bull., 59, p. 601Riella, H.G., Durazzo, M., Hirata, M., Nogueira, R.A., (1991) J. Nucl. Mater., 178, p. 204Yuda, R., Une, K., (1991) J. Nucl. Mater., 178, p. 195Miyake, C., Kanamaru, M., Imoto, S., (1986) J. Nucl. Mater., 138, p. 142TECDOC-844, International Atomic Energy Agency, Characteristics and Use of Urania-Gadolinia Fuels, ISSN 1011-4289, Vienna, Austria, 1995Gündüz, G., Uslu, I., Önal, I.I., Durmazuçar, H.H., Öztürk, T., Aksit, A.A., Kopuz, B., Uzmen, R., (1995) Nucl. Technol., 11, p. 63Song, K.W., Kim, K.S., Kang, K.W., Jung, Y.H., (2003) J. Nucl. Mater., 317, p. 204Hirai, M., (1990) J. Nucl. Mater., 173, p. 247Hälldahl, L., Eriksson, S., (1988) J. Nucl. Mater., 153, p. 66Leyva, A.G., Vega, D., Trimarco, V., Marchi, D.J., (2002) J. Nucl. Mater., 303, p. 29T.A. Restivo, A.E. Cláudio, E.E. Silva, L. Pagano Jr., in: TECDOC-1416, International Atomic Energy Agency, 'Advanced Fuel Pellet Materials and Designs for Water Cooled Reactors', ISSN 1011-4289, Vienna, Austria, 2004, p. 147T.A. Restivo, L. Pagano Jr., in: Proceedings of the Conference on Characterization and Quality Control of Nuclear Fuels, ISBN 81-7764-608-7, Allied Publishers, New Delhi, India, 2004, p. 139Czjzek, G., (1993) Mössbauer Spectroscopy Applied to Magnetism and Materials Science, , Long G.J., and Grandjean F. (Eds), Plenum, New York (Chapter 9)Cullity, B.D., (1967) Elements of X-ray Diffraction, , Addison-WesleyCashion, J.D., Prowse, D.B., Vas, A., (1973) J. Phys. C: Solid State Phys., 6, p. 2611Ohmichi, T., Fukushima, S., Maeda, A., Watanabe, H., (1981) J. Nucl. Mater., 102, p. 4