Influences of La3+ substitution on the structure and magnetic properties of M-type strontium ferrites |
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| Affiliation: | 1. National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, People''s Republic of China;2. Xi’an Jiaotong University, Xi’an 710049, People''s Republic of China;3. State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, People''s Republic of China;1. Department of Physics, Bahauddin Zakariya University, Multan 60800, Pakistan;2. Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan;3. Department of Physics, COMSATS Institute of Information Technology, Lahore 54000, Pakistan;4. Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan;1. Department of Physics, Indian Institute of Technology Patna, Bihta, Patna 801106, India;2. Aryabhatta Centre for Nanoscience and Nanotechnology, Aryabhatta Knowledge University, Patna 800001, India;1. School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China;2. Centre for Advanced Studies in Physics, GC University, Lahore 54000, Pakistan;1. Motor R&D Group, Samsung Electronics, 443-742 Suwon, South Korea;2. Materials R&D Center, Samsung Advanced Institute of Technology, Samsung Electronics, 443-742 Suwon, South Korea;1. Department of Physics, BS&H, Swarnandhra College of Engineering and Technology, Narsapur, 534280, India;2. Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea;3. Department of Physics, BS&H, Sree Vidyanikethan Engineering College, Tirupati 517102, A.P, India;4. Department of Physics, Andhra University, Visakhapatnam, 530003, India |
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| Abstract: | M-type strontium ferrites with substitution of Sr2+ by rare-earth La3+, according to the formula Sr1−xLaxFe12O19, are prepared by the ceramic process. Influences of the substituted amount of La3+ on structure and magnetic properties of Sr1−xLaxFe12O19 compounds have systematically been investigated by XRD, VSM and Mössbauer spectrum. When the substituted amount x is below 0.30, X-ray diffraction shows that the samples are single M-type hexagonal ferrites. It is found that the suitable amount of La3+ substitution may remarkably increase saturation magnetization σs and intrinsic coercivity HcJ. With the La3+ addition for the same sintering temperature, σs and HcJ increase at first, then decrease gradually. However, the substituted amount x at the maximum value of HcJ is bigger than that of σs. Mössbauer spectroscopy of 57Fe in Sr1−xLaxFe12O19 has shown that the substitution of Sr2+ by La3+ is associated with a valence change of Fe3+ to Fe2+ at 2a or 4f2 site. The magnetic properties are reflected in the Mössbauer spectra which indicate that the magnetic hyperfine field (Hhf) is detected with the highest value at x=0.20. The different exchange paths between the iron sublattices are discussed according to the increased hyperfine fields of the 12k- and 2b-site. The Curie temperature of Sr1−xLaxFe12O19 decreases linearly with increasing La3+ substitution. |
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