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Title: A new family of manganese(II,III)-rare earth pyrochlores

Abstract

Polycrystalline samples of a new family of blackish brown pyrochlores of composition Mn{sub 2}R{sub 2}-[MnSb{sub 3}]O{sub 14} (R = Y, In, La, Pr, Nd, Sm-Lu), with two Mn{sup 2+} and one Mn{sup 3+} per formula, have been prepared by heating mixtures of reagent grade MnO{sub 2}, R{sub 2}O{sub 3}, and Sb{sub 2}O{sub 3} to 1280 or 1300 C in stoichiometric molar ratios. The composition was established by chemical analysis and confirmed by X-ray powder diffraction methods, neutron powder diffraction data for the Y and Ho compounds, and magnetization measurements. These pyrochlores crystallize in the Fd{bar 3}m space group (no. 227) with Z = 4. All of the atoms are in special positions and show only one variable position parameter, u. The unit-cell dimensions, a ({angstrom}), range from 10.1227(8) (R = IN), to 10.347(2), (R = La). The oxygen positional u parameters were determined from X-ray powder diffraction data for 2Mn+2R at (c) sites, Mn+3Sb at (d) positions, and the origin at the inversion center; and vary from u = 0.420 (R = Y) to u = 0.429 (R = Pr). Neutron diffraction data for R = Y and Ho gave u = 0.42167(7) and u = 0.42162(9), respectively. Interatomic distancesmore » are given. Magnetization measurements from 4 to 350 K are consistent with high spin Mn{sup 2+} and high spin Mn{sup 3+} at (c) and (d) positions, respectively. The possibility of predicting u parameters in pyrochlores from a values and ionic radii is discussed.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. de Navarra, Pamplona (ES)
OSTI Identifier:
20080261
Resource Type:
Journal Article
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 12; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 0897-4756
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; PYROCHLORE; MANGANESE OXIDES; CRYSTAL STRUCTURE; MAGNETIC PROPERTIES

Citation Formats

Casado, P.G., Alonso, J.A., Martinez, J.L., Fernandez, M.T., and Rasines, I. A new family of manganese(II,III)-rare earth pyrochlores. United States: N. p., 2000. Web. doi:10.1021/cm9902669.
Casado, P.G., Alonso, J.A., Martinez, J.L., Fernandez, M.T., & Rasines, I. A new family of manganese(II,III)-rare earth pyrochlores. United States. doi:10.1021/cm9902669.
Casado, P.G., Alonso, J.A., Martinez, J.L., Fernandez, M.T., and Rasines, I. Mon . "A new family of manganese(II,III)-rare earth pyrochlores". United States. doi:10.1021/cm9902669.
@article{osti_20080261,
title = {A new family of manganese(II,III)-rare earth pyrochlores},
author = {Casado, P.G. and Alonso, J.A. and Martinez, J.L. and Fernandez, M.T. and Rasines, I.},
abstractNote = {Polycrystalline samples of a new family of blackish brown pyrochlores of composition Mn{sub 2}R{sub 2}-[MnSb{sub 3}]O{sub 14} (R = Y, In, La, Pr, Nd, Sm-Lu), with two Mn{sup 2+} and one Mn{sup 3+} per formula, have been prepared by heating mixtures of reagent grade MnO{sub 2}, R{sub 2}O{sub 3}, and Sb{sub 2}O{sub 3} to 1280 or 1300 C in stoichiometric molar ratios. The composition was established by chemical analysis and confirmed by X-ray powder diffraction methods, neutron powder diffraction data for the Y and Ho compounds, and magnetization measurements. These pyrochlores crystallize in the Fd{bar 3}m space group (no. 227) with Z = 4. All of the atoms are in special positions and show only one variable position parameter, u. The unit-cell dimensions, a ({angstrom}), range from 10.1227(8) (R = IN), to 10.347(2), (R = La). The oxygen positional u parameters were determined from X-ray powder diffraction data for 2Mn+2R at (c) sites, Mn+3Sb at (d) positions, and the origin at the inversion center; and vary from u = 0.420 (R = Y) to u = 0.429 (R = Pr). Neutron diffraction data for R = Y and Ho gave u = 0.42167(7) and u = 0.42162(9), respectively. Interatomic distances are given. Magnetization measurements from 4 to 350 K are consistent with high spin Mn{sup 2+} and high spin Mn{sup 3+} at (c) and (d) positions, respectively. The possibility of predicting u parameters in pyrochlores from a values and ionic radii is discussed.},
doi = {10.1021/cm9902669},
journal = {Chemistry of Materials},
issn = {0897-4756},
number = 5,
volume = 12,
place = {United States},
year = {2000},
month = {5}
}