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Title: The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses

Abstract

Highlights: • The formation of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} is investigated. • Pre-milling the reactants substantially lowers the formation temperature. • The core and surface structures were studied. • XRD and {sup 57}Fe Mössbauer spectroscopic analyses indicate the δ-value to be 0.60. • XPS shows a complex surface structure for the mechanosynthesized Sr{sub 3}Fe{sub 2}O{sub 7−δ} nanoparticles. - Abstract: The influence of ball milling and subsequent sintering of a 3:1 molar mixture of SrCO{sub 3} and α-Fe{sub 2}O{sub 3} on the formation of Sr{sub 3}Fe{sub 2}O{sub 7−δ} double perovskite is investigated with different analytical techniques. Milling the mixture for 110 h leads to the formation of SrCO{sub 3}-α-Fe{sub 2}O{sub 3} nanocomposites and the structural deformation of α-Fe{sub 2}O{sub 3} via the incorporation of Sr{sup 2+} ions. Subsequent sintering of the pre-milled reactants’ mixture has led to the partial formation of an SrFeO{sub 3} perovskite-related phase in the temperature range 400–600 °C. This was followed by the progressive development of an Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase that continued to increase with increasing sintering temperature until a single-phased nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase was attained at 950 °C (12 h). This temperature is ∼350 °C lower than the temperaturemore » at which the material is prepared conventionally using the ceramic method. The evolution of different structural phases during the reaction process is discussed. Rietveld refinement of the X-ray diffraction data shows a value of 0.60 for the oxygen deficiency δ, in consistency with the Fe{sup 3+}/Fe{sup 4+} ratio derived from the {sup 57}Fe Mössbauer data recorded at both 300 K and 78 K. The Mössbauer data suggests that the Sr{sub 3}Fe{sub 2}O{sub 6.4} nanoparticles are superparamagnetic with blocking temperatures below 78 K. The surfaces of the Sr{sub 3}Fe{sub 2}O{sub 6.4} nanoparticles were shown to have a complex structure and composition relative to those of their cores with traces of SrCO{sub 3}, SrO and SrFeO{sub 3−δ} being detected.« less

Authors:
 [1]; ;  [1];  [2]; ; ;  [1]
  1. Department of Physics, Sultan Qaboos University, P.O. Box 36, 123 Al-Khoud, Muscat (Oman)
  2. Chemistry Department, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)
Publication Date:
OSTI Identifier:
22475766
Resource Type:
Journal Article
Journal Name:
Materials Research Bulletin
Additional Journal Information:
Journal Volume: 65; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0025-5408
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; DEFORMATION; FERRITES; IRON 57; MIXTURES; MOESSBAUER EFFECT; NANOCOMPOSITES; NANOPARTICLES; NANOSTRUCTURES; OXYGEN; PEROVSKITE; SINTERING; STRONTIUM COMPOUNDS; STRONTIUM OXIDES; SUPERPARAMAGNETISM; SURFACES; SYNTHESIS; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Al-Rawas, A.D., E-mail: arawas@squ.edu.om, Widatallah, H.M., Al-Harthi, S.H., Johnson, C., Gismelseed, A.M., Elzain, M.E., and Yousif, A.A. The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses. United States: N. p., 2015. Web. doi:10.1016/J.MATERRESBULL.2015.01.026.
Al-Rawas, A.D., E-mail: arawas@squ.edu.om, Widatallah, H.M., Al-Harthi, S.H., Johnson, C., Gismelseed, A.M., Elzain, M.E., & Yousif, A.A. The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses. United States. doi:10.1016/J.MATERRESBULL.2015.01.026.
Al-Rawas, A.D., E-mail: arawas@squ.edu.om, Widatallah, H.M., Al-Harthi, S.H., Johnson, C., Gismelseed, A.M., Elzain, M.E., and Yousif, A.A. Fri . "The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses". United States. doi:10.1016/J.MATERRESBULL.2015.01.026.
@article{osti_22475766,
title = {The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses},
author = {Al-Rawas, A.D., E-mail: arawas@squ.edu.om and Widatallah, H.M. and Al-Harthi, S.H. and Johnson, C. and Gismelseed, A.M. and Elzain, M.E. and Yousif, A.A.},
abstractNote = {Highlights: • The formation of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} is investigated. • Pre-milling the reactants substantially lowers the formation temperature. • The core and surface structures were studied. • XRD and {sup 57}Fe Mössbauer spectroscopic analyses indicate the δ-value to be 0.60. • XPS shows a complex surface structure for the mechanosynthesized Sr{sub 3}Fe{sub 2}O{sub 7−δ} nanoparticles. - Abstract: The influence of ball milling and subsequent sintering of a 3:1 molar mixture of SrCO{sub 3} and α-Fe{sub 2}O{sub 3} on the formation of Sr{sub 3}Fe{sub 2}O{sub 7−δ} double perovskite is investigated with different analytical techniques. Milling the mixture for 110 h leads to the formation of SrCO{sub 3}-α-Fe{sub 2}O{sub 3} nanocomposites and the structural deformation of α-Fe{sub 2}O{sub 3} via the incorporation of Sr{sup 2+} ions. Subsequent sintering of the pre-milled reactants’ mixture has led to the partial formation of an SrFeO{sub 3} perovskite-related phase in the temperature range 400–600 °C. This was followed by the progressive development of an Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase that continued to increase with increasing sintering temperature until a single-phased nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase was attained at 950 °C (12 h). This temperature is ∼350 °C lower than the temperature at which the material is prepared conventionally using the ceramic method. The evolution of different structural phases during the reaction process is discussed. Rietveld refinement of the X-ray diffraction data shows a value of 0.60 for the oxygen deficiency δ, in consistency with the Fe{sup 3+}/Fe{sup 4+} ratio derived from the {sup 57}Fe Mössbauer data recorded at both 300 K and 78 K. The Mössbauer data suggests that the Sr{sub 3}Fe{sub 2}O{sub 6.4} nanoparticles are superparamagnetic with blocking temperatures below 78 K. The surfaces of the Sr{sub 3}Fe{sub 2}O{sub 6.4} nanoparticles were shown to have a complex structure and composition relative to those of their cores with traces of SrCO{sub 3}, SrO and SrFeO{sub 3−δ} being detected.},
doi = {10.1016/J.MATERRESBULL.2015.01.026},
journal = {Materials Research Bulletin},
issn = {0025-5408},
number = ,
volume = 65,
place = {United States},
year = {2015},
month = {5}
}