Structural and magnetic properties of Al-doped yttrium iron garnet ceramics: Fe-57 internal field NMR and Mossbauer spectroscopy study

Mahour, Laxmi Narayan and Manjunatha, M and Choudhary, Harish Kumar and Kumar, Rajeev and Anupama, A and Damle, R and Ramesh, KP and Sahoo, Balaram (2019) Structural and magnetic properties of Al-doped yttrium iron garnet ceramics: Fe-57 internal field NMR and Mossbauer spectroscopy study. In: JOURNAL OF ALLOYS AND COMPOUNDS, 773 . pp. 612-622.

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Abstract

The structural and magnetic properties of Al substituted yttrium-iron garnet (Y3AlxFe5-xO12, x = 0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6 and 1.8) ceramic powders synthesized using solution combustion method were investigated. Post combustion, the samples were calcination at 1045 degrees C for 6 h and subsequently at 1200 degrees C for 6 h to obtain phase-pure garnets. X-ray diffraction (XRD) results confirm the formation of garnets with la (3) over bard structure. The occupancy of Y3+ ions in the dodecahedral site and the distribution of Al3+ and Fe3+ ions in the tetrahedral and octahedral sites in the bcc structure of the garnet were confirmed by Rietveld refinement of XRD patterns, Mossbauer spectroscopy and( 57)Fe internal field NMR spectroscopy. For low Al content, Al3+ ions have preference to occupy tetrahedral (T-d) sites than the octahedral (O-h) sites. At higher Al content the distribution of Al tends towards a ratio of 3:2 at the tetrahedral:octahedral site. Increase in Al doping results in the decrease in the lattice parameter due to smaller size of Al-3 + as compared to Fe3+ ion. All the studied samples show coral-network-like surface morphology. The saturation magnetization (M-s) values decrease from -26.94 emu/g to 0.17 emu/g with increase in Al content from 0.0 to 1.8. Further addition of Al makes the sample paramagnetic at RT. Substitution of non-magnetic Al3+ reduces the saturation magnetization rapidly due to the decrease in the superexchange interaction in the crystal. (C) 2018 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF ALLOYS AND COMPOUNDS
Publisher:	ELSEVIER SCIENCE SA
Additional Information:	Copy right for this article belong to ELSEVIER SCIENCE SA
Keywords:	Yttrium iron garnet; Solution combustion; Reitveld refinement; Mossbauer spectroscopy; Fe- 57 internal field NMR
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Physical & Mathematical Sciences > Physics
Date Deposited:	26 Nov 2018 15:12
Last Modified:	26 Nov 2018 15:12
URI:	http://eprints.iisc.ac.in/id/eprint/61155

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