Magnetite-based glass-ceramics prepared by controlled crystallization of borosilicate glasses: Effect of nucleating agents on magnetic properties and relaxation |
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| Affiliation: | 1. National Institute of Materials Physics, Bucharest, Magurele 077125, Romania;2. Department of Physics, US Naval Academy, Annapolis, MD, USA;3. Bucharest University, Faculty of Physics, 077125 Bucharest, Magurele, Romania;1. Faculdade de Educação Ciências e Letras do Sertão Central, Universidade Estadual do Ceará Quixadá, CE 63.900-000, Brazil;2. Deparamento de Física, Universidade Federal do Ceará, Fortaleza, CE 60455-760, Brazil;3. Instituto de Ciências Exatas, Universidade Federal do Sul e Sudeste do Pará, CEP 68.505-080 Marabá, PA, Brazil;4. Universidade Federal do Cariri, 63000-000 Juazeiro do Norte, CE, Brazil;1. Department of Physics, i3N, University of Aveiro, 3810-193 Aveiro, Portugal;2. CICECO – Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro, Portugal;3. National University of Science and Technology “MISiS”, 119049 Moscow, Russia;4. Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal;1. Integrated Nanotechnology Research Center (INRC), Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand;2. National Metal and Materials Technology Center, 114 Thailand Science Park, Paholyothin Rd. Klong 1, Klong Luang, Pathunthani 12120, Thailand;3. Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Muang District, Nakhon Ratchasima 30000, Thailand;1. School of Materials Science and Engineering, Anhui University of Technology, Maanshan 243032, PR China;2. Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 210009, PR China;3. Key Laboratory of Metallurgical Emission Reduction & Resources Recycling, Ministry of Education, Anhui University of Technology, Maanshan 243002, PR China |
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| Abstract: | The specific magnetic structure and magnetic relaxation phenomena in magnetite nanoentities grown in a glassy matrix by controlled crystallization of Fe-containing borosilicate and boroaluminosilicate glasses in the presence of two types of nucleating agents, Cr2O3 and P2O5, were investigated. The structure, morphology and magnetic properties are strongly influenced by the nucleating agents. Cr2O3 generates magnetite-based glass ceramics with magnetite configurations showing an upward relaxation of magnetization at low and high temperatures but downward at intermediate temperatures. The magnetite grown with P2O5 displays only downward relaxation but with different signs of the temperature derivative of the relaxation rate S in different temperature ranges. The observed effects are discussed with respect to the following factors: i) the existence of a multimodal size distribution of the magnetite (nano)particles as revealed by high resolution electron microscopy; ii) the degree of occupation of different sublattices of the magnetite structure with Fe3+ and Fe2+ ions; and iii) the interplay between the relaxation mechanisms in different temperature ranges. |
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| Keywords: | Magnetite Glass ceramics Mössbauer spectroscopy Ac susceptibility Magnetic relaxation Superparamagnetism |
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