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Title: Neutron and X-ray powder diffraction study of RBa{sub 2}Fe{sub 3}O{sub 8+w} phases

Abstract

Compounds of composition RBa{sub 2}Fe{sub 3}O{sub 8+w} (R = La, Nd, Sm, Gd, Dy, Er, Yb, Lu, and Y) with variable oxygen content have been synthesized using the liquid mixing technique and have been analyzed by powder X-ray and neutron diffraction methods. A triple perovskite-type structure with ordered Ba and R cations and having the symmetry of space group P4/mmm was obtained only for R = Y, Dy, and Er, whereas the larger R atoms gave the atomic arrangement of disordered, defective perovskites with average symmetry Pm{bar 3}m. No perovskite-type phases were obtained when Yb and Lu were tried. The oxygen content of the oxygen-saturated phases was found to increase with increasing size of the cation R from w = 0.07 for Er to w = 0.83 for La. The Neel temperature ({approximately}650 K) and the magnitude of the Fe magnetic moment ({approximately}3.3 {mu}{sub B} at room temperature) are highest when trivalent iron is involved (w = 0), but these quantities are rather insensitive to the nature of R and to slight variations of oxygen content in the triple perovskite-type structure of the Y, Dy, and Er compounds. In the case of the cubic structures, however, both quantities depend stronglymore » on the oxygen stoichiometry. In the magnetically ordered state, nearest-neighbor iron moments are coupled antiferromagnetically along the three crystallographic directions in all samples, resulting in magnetic structures with symmetry Imm{prime}m and magnetic unit cells related to those of the corresponding nuclear structures by the transformation matrix (1{bar 1}0/110/002).« less

Authors:
;  [1];  [2]; ; ; ; ; ;  [3]
  1. Univ. of Oslo, Blindern, (Norway). Dept. of Chemistry
  2. Univ. of Maryland, College Park, MD (United States)
  3. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Reactor Radiation Div.
Publication Date:
OSTI Identifier:
642193
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 136; Journal Issue: 1; Other Information: PBD: 15 Feb 1998
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; RARE EARTH COMPOUNDS; OXIDES; BARIUM OXIDES; IRON OXIDES; PEROVSKITES; NEUTRON DIFFRACTION; X-RAY DIFFRACTION; LATTICE PARAMETERS; EXPERIMENTAL DATA

Citation Formats

Karen, P, Kjekshus, A, Huang, Q, National Inst. of Standards and Technology, Gaithersburg, MD, Lynn, J W, Rosov, N, Sora, I N, Karen, V L, Mighell, A D, and Santoro, A. Neutron and X-ray powder diffraction study of RBa{sub 2}Fe{sub 3}O{sub 8+w} phases. United States: N. p., 1998. Web. doi:10.1006/jssc.1997.7636.
Karen, P, Kjekshus, A, Huang, Q, National Inst. of Standards and Technology, Gaithersburg, MD, Lynn, J W, Rosov, N, Sora, I N, Karen, V L, Mighell, A D, & Santoro, A. Neutron and X-ray powder diffraction study of RBa{sub 2}Fe{sub 3}O{sub 8+w} phases. United States. https://doi.org/10.1006/jssc.1997.7636
Karen, P, Kjekshus, A, Huang, Q, National Inst. of Standards and Technology, Gaithersburg, MD, Lynn, J W, Rosov, N, Sora, I N, Karen, V L, Mighell, A D, and Santoro, A. 1998. "Neutron and X-ray powder diffraction study of RBa{sub 2}Fe{sub 3}O{sub 8+w} phases". United States. https://doi.org/10.1006/jssc.1997.7636.
@article{osti_642193,
title = {Neutron and X-ray powder diffraction study of RBa{sub 2}Fe{sub 3}O{sub 8+w} phases},
author = {Karen, P and Kjekshus, A and Huang, Q and National Inst. of Standards and Technology, Gaithersburg, MD and Lynn, J W and Rosov, N and Sora, I N and Karen, V L and Mighell, A D and Santoro, A},
abstractNote = {Compounds of composition RBa{sub 2}Fe{sub 3}O{sub 8+w} (R = La, Nd, Sm, Gd, Dy, Er, Yb, Lu, and Y) with variable oxygen content have been synthesized using the liquid mixing technique and have been analyzed by powder X-ray and neutron diffraction methods. A triple perovskite-type structure with ordered Ba and R cations and having the symmetry of space group P4/mmm was obtained only for R = Y, Dy, and Er, whereas the larger R atoms gave the atomic arrangement of disordered, defective perovskites with average symmetry Pm{bar 3}m. No perovskite-type phases were obtained when Yb and Lu were tried. The oxygen content of the oxygen-saturated phases was found to increase with increasing size of the cation R from w = 0.07 for Er to w = 0.83 for La. The Neel temperature ({approximately}650 K) and the magnitude of the Fe magnetic moment ({approximately}3.3 {mu}{sub B} at room temperature) are highest when trivalent iron is involved (w = 0), but these quantities are rather insensitive to the nature of R and to slight variations of oxygen content in the triple perovskite-type structure of the Y, Dy, and Er compounds. In the case of the cubic structures, however, both quantities depend strongly on the oxygen stoichiometry. In the magnetically ordered state, nearest-neighbor iron moments are coupled antiferromagnetically along the three crystallographic directions in all samples, resulting in magnetic structures with symmetry Imm{prime}m and magnetic unit cells related to those of the corresponding nuclear structures by the transformation matrix (1{bar 1}0/110/002).},
doi = {10.1006/jssc.1997.7636},
url = {https://www.osti.gov/biblio/642193}, journal = {Journal of Solid State Chemistry},
number = 1,
volume = 136,
place = {United States},
year = {Sun Feb 15 00:00:00 EST 1998},
month = {Sun Feb 15 00:00:00 EST 1998}
}