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Title: Syntheses and Characterizations of Complex Perovskite Oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9

Abstract

The following complex oxynitride perovskites have been prepared: LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. Synchrotron X-ray powder diffraction analyses show that LaMg1/3Ta2/3O2N and LaMg1/2Ta1/2O5/2N1/2 are isostructural to the oxide La2Mg(Mg1/3Ta2/3)O6 (space group P21/n), whereas BaSc0.05Ta0.95O2.1N0.9 has a simple cubic symmetry similarly to BaTaO2N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La2Mg(Mg1/3Ta2/3)O6 and Ba2ScTaO6. The optical band gaps are similar for the homologous compositions, LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2 and LaTaON2 (1.9 eV), and BaSc0.05Ta0.95O2.1N0.9 and BaTaO2N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta5+. Impedance spectroscopy reveals interesting capacitor geometry in BaSc0.05Ta0.95O2.1N0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc0.05Ta0.95O2.1N0.9 has a bulk component with a high relative permittivity ({kappa}=7300) and the grain boundary component with an even higher {kappa}.

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
959913
Report Number(s):
BNL-82899-2009-JA
Journal ID: ISSN 0022-4596; JSSCBI; TRN: US1005836
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; ABSORPTION; CAPACITORS; CATIONS; DIELECTRIC MATERIALS; DIFFRACTION; GEOMETRY; IMPEDANCE; OXIDES; PERMITTIVITY; PEROVSKITE; PEROVSKITES; SPECTROSCOPY; SYMMETRY; SYNCHROTRONS; national synchrotron light source

Citation Formats

Kim,Y., and Woodward, P. Syntheses and Characterizations of Complex Perovskite Oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2007.08.031.
Kim,Y., & Woodward, P. Syntheses and Characterizations of Complex Perovskite Oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. United States. doi:10.1016/j.jssc.2007.08.031.
Kim,Y., and Woodward, P. Mon . "Syntheses and Characterizations of Complex Perovskite Oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9". United States. doi:10.1016/j.jssc.2007.08.031.
@article{osti_959913,
title = {Syntheses and Characterizations of Complex Perovskite Oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9},
author = {Kim,Y. and Woodward, P.},
abstractNote = {The following complex oxynitride perovskites have been prepared: LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. Synchrotron X-ray powder diffraction analyses show that LaMg1/3Ta2/3O2N and LaMg1/2Ta1/2O5/2N1/2 are isostructural to the oxide La2Mg(Mg1/3Ta2/3)O6 (space group P21/n), whereas BaSc0.05Ta0.95O2.1N0.9 has a simple cubic symmetry similarly to BaTaO2N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La2Mg(Mg1/3Ta2/3)O6 and Ba2ScTaO6. The optical band gaps are similar for the homologous compositions, LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2 and LaTaON2 (1.9 eV), and BaSc0.05Ta0.95O2.1N0.9 and BaTaO2N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta5+. Impedance spectroscopy reveals interesting capacitor geometry in BaSc0.05Ta0.95O2.1N0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc0.05Ta0.95O2.1N0.9 has a bulk component with a high relative permittivity ({kappa}=7300) and the grain boundary component with an even higher {kappa}.},
doi = {10.1016/j.jssc.2007.08.031},
journal = {Journal of Solid State Chemistry},
number = 11,
volume = 180,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}