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Fe-57 internal field nuclear magnetic resonance and Mossbauer spectroscopy study of Li-Zn ferrites

Anupama, AV and Manjunatha, M and Rathod, V and Jali, VM and Damle, R and Ramesh, KP and Sahoo, B (2018) Fe-57 internal field nuclear magnetic resonance and Mossbauer spectroscopy study of Li-Zn ferrites. In: JOURNAL OF MAGNETIC RESONANCE, 286 . pp. 68-77.

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Official URL: http://dx.doi.org/10.1016/j.jmr.2017.11.012

Abstract

We report the internal field nuclear magnetic resonance (IFNMR) and Mossbauer spectroscopy study of Li-Zn ferrites at RT. The results were supported by the IFNMR data measured at 77 K. As Zn concentration increases the IFNMR echo amplitude decreases and below certain Zn concentration no signal was detected. At RT the echo amplitude vanishes at a lower Zn concentration, whereas at 77 K, the echo amplitude does not vanish completely (except for pure Zn-ferrite). However, in Mossbauer spectroscopy at RT, we have observed magnetically ordered state of all the Li-Zn ferrite samples. This discrepancy could be related to the difference between the time scale of detection of the spins by Mossbauer spectroscopy (10(-7)-10(-10) s) and NMR spectroscopy (10(-6) s). Hence, sensitivity of zero-field NMR depends on the magnetic hyperfine field, temperature and abundance of the magnetic cations at the lattice of the spinel ferrites. We have demonstrated that the `two-equal-pulses' sequence leads to higher echo signal than the spin echo pulse sequence due to the presence of distribution of internal magnetic fields throughout the material. We obtained a limiting value for the fraction of spins needed to produce an echo signal at a particular temperature and at a particular site of the Li-Zn ferrite spinels that can be sensitively detected by pulsed IFNMR technique. (C) 2017 Elsevier Inc. All rights reserved.

Item Type: Journal Article
Additional Information: Copy right for this article belong to the ACADEMIC PRESS INC ELSEVIER SCIENCE, 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 02 Mar 2018 14:54
Last Modified: 21 Feb 2019 09:42
URI: http://eprints.iisc.ac.in/id/eprint/59058

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