High-Pressure Mössbauer Measurements on Nanocrystalline Perovskite (La,Sr)(Mn,Fe)O3 |
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Authors: | Usha Chandra Prerana Mudgal Manoj Kumar Rajeev Rawat G Parthasarathy Nita Dilawar A K Bandyopadhyay |
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Institution: | (1) Department of Physics, University of Rajasthan, Jaipur, 302004, India;(2) UGC/DAE Consortium for Scientific Research, Khandawa Road, Indore, 452017, India;(3) National Geophysical Research Institute, Hyderabad, 500 007, India;(4) National Physical Laboratory, Pusa Road, New Delhi, 110012, India |
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Abstract: | We report here the Mössbauer measurements on nanocrystalline perovskite structured manganite La0.8Sr0.2Mn0.8Fe0.19
57Fe0.01O3 as a function of pressure up to 10 GPa at room temperature. The nanocrystalline sample, prepared by sol–gel technique found to have crystallite sizes of ∼138 ± 10 Å. Zero-field electrical resistivity measurements with temperature support the nanocrystalline nature. At ambient pressure, Fe3+ as well as Fe4+ ions are distributed in two different environments – Fe3+ in low symmetric site surrounded by Mn3+ ions only while Fe4+ in high symmetric site with at least one Mn3+ ion. Pressure seems to affect the higher symmetric site. A sudden increase in isomer shift at 0.52 GPa indicates the first order phase transition representing the transformation of Fe4+ to Fe3+. Another transition at 3.7 GPa, represents the presence of Fe3+ in single kind of environment. Pressure dependence of electrical resistivity measurements verifies the transitions attributing the first order transition to the cross over of localized-electron to band magnetism. |
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Keywords: | high-pressure electrical resistivity high-pressure Mö ssbauer spectroscopy manganite nanocrystalline perovskite |
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