Defect and electronic structures of calcium-doped lanthanum cuprate

John Okasinski, Jerome B. Cohen, Jinha Hwang, Thomas O Mason, Zenong Ding, Oliver Warschkow, Donald E. Ellis

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Quenched calcium-doped lanthanum cuprate (La2CuO4) samples were examined at room temperature using extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge spectroscopy (XANES) near the CaK edge, and via atomic- and electronic-structure modeling. Calculations and experiments show that the Ca atom, in a manner similar to that of Sr and Ba atoms, replaces the La atom and maintains its nine-fold coordination above the center of a CuO4 square, which is the nominal position of the La atom. In contrast to the Sr and Ba atoms, the distances from Ca to its nearest neighbors are similar to the size of the La3+ cation. The distances that are obtained from the simulation are in reasonable agreement with the experimental results for calcium, as well as previous studies that involved strontium and barium. The binding of a calcium dopant to vacancies on the O(1) sites is stable, but only slightly; therefore, there are probably many different types of such clusters. This calculated binding also is supported by the EXAFS data. The overall electronic structure is similar to that observed in calculations for pure La2CuO4: the LaO planes remain ionic, even with the presence of the calcium dopant, and the Cu-O(1) bond is covalent. The calcium is ionic in character, with a net charge of 1.6, and the narrow Ca 3d band lies approx. 6 eV above the Fermi energy level.

Original languageEnglish
Pages (from-to)2451-2459
Number of pages9
JournalJournal of the American Ceramic Society
Volume82
Issue number9
Publication statusPublished - Sep 1999

Fingerprint

Lanthanum
Defect structures
Electronic structure
Calcium
X ray absorption
Atoms
Doping (additives)
Crystal atomic structure
Strontium
Covalent bonds
Barium
Fermi level
Electron energy levels
Vacancies
Cations
Positive ions
Spectroscopy
Experiments

ASJC Scopus subject areas

  • Ceramics and Composites

Cite this

Okasinski, J., Cohen, J. B., Hwang, J., Mason, T. O., Ding, Z., Warschkow, O., & Ellis, D. E. (1999). Defect and electronic structures of calcium-doped lanthanum cuprate. Journal of the American Ceramic Society, 82(9), 2451-2459.

Defect and electronic structures of calcium-doped lanthanum cuprate. / Okasinski, John; Cohen, Jerome B.; Hwang, Jinha; Mason, Thomas O; Ding, Zenong; Warschkow, Oliver; Ellis, Donald E.

In: Journal of the American Ceramic Society, Vol. 82, No. 9, 09.1999, p. 2451-2459.

Research output: Contribution to journalArticle

Okasinski, J, Cohen, JB, Hwang, J, Mason, TO, Ding, Z, Warschkow, O & Ellis, DE 1999, 'Defect and electronic structures of calcium-doped lanthanum cuprate', Journal of the American Ceramic Society, vol. 82, no. 9, pp. 2451-2459.
Okasinski J, Cohen JB, Hwang J, Mason TO, Ding Z, Warschkow O et al. Defect and electronic structures of calcium-doped lanthanum cuprate. Journal of the American Ceramic Society. 1999 Sep;82(9):2451-2459.
Okasinski, John ; Cohen, Jerome B. ; Hwang, Jinha ; Mason, Thomas O ; Ding, Zenong ; Warschkow, Oliver ; Ellis, Donald E. / Defect and electronic structures of calcium-doped lanthanum cuprate. In: Journal of the American Ceramic Society. 1999 ; Vol. 82, No. 9. pp. 2451-2459.
@article{a0fa6c6fb51e48a6ac27bc4ea46741e9,
title = "Defect and electronic structures of calcium-doped lanthanum cuprate",
abstract = "Quenched calcium-doped lanthanum cuprate (La2CuO4) samples were examined at room temperature using extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge spectroscopy (XANES) near the CaK edge, and via atomic- and electronic-structure modeling. Calculations and experiments show that the Ca atom, in a manner similar to that of Sr and Ba atoms, replaces the La atom and maintains its nine-fold coordination above the center of a CuO4 square, which is the nominal position of the La atom. In contrast to the Sr and Ba atoms, the distances from Ca to its nearest neighbors are similar to the size of the La3+ cation. The distances that are obtained from the simulation are in reasonable agreement with the experimental results for calcium, as well as previous studies that involved strontium and barium. The binding of a calcium dopant to vacancies on the O(1) sites is stable, but only slightly; therefore, there are probably many different types of such clusters. This calculated binding also is supported by the EXAFS data. The overall electronic structure is similar to that observed in calculations for pure La2CuO4: the LaO planes remain ionic, even with the presence of the calcium dopant, and the Cu-O(1) bond is covalent. The calcium is ionic in character, with a net charge of 1.6, and the narrow Ca 3d band lies approx. 6 eV above the Fermi energy level.",
author = "John Okasinski and Cohen, {Jerome B.} and Jinha Hwang and Mason, {Thomas O} and Zenong Ding and Oliver Warschkow and Ellis, {Donald E.}",
year = "1999",
month = "9",
language = "English",
volume = "82",
pages = "2451--2459",
journal = "Journal of the American Ceramic Society",
issn = "0002-7820",
publisher = "Wiley-Blackwell",
number = "9",

}

TY - JOUR

T1 - Defect and electronic structures of calcium-doped lanthanum cuprate

AU - Okasinski, John

AU - Cohen, Jerome B.

AU - Hwang, Jinha

AU - Mason, Thomas O

AU - Ding, Zenong

AU - Warschkow, Oliver

AU - Ellis, Donald E.

PY - 1999/9

Y1 - 1999/9

N2 - Quenched calcium-doped lanthanum cuprate (La2CuO4) samples were examined at room temperature using extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge spectroscopy (XANES) near the CaK edge, and via atomic- and electronic-structure modeling. Calculations and experiments show that the Ca atom, in a manner similar to that of Sr and Ba atoms, replaces the La atom and maintains its nine-fold coordination above the center of a CuO4 square, which is the nominal position of the La atom. In contrast to the Sr and Ba atoms, the distances from Ca to its nearest neighbors are similar to the size of the La3+ cation. The distances that are obtained from the simulation are in reasonable agreement with the experimental results for calcium, as well as previous studies that involved strontium and barium. The binding of a calcium dopant to vacancies on the O(1) sites is stable, but only slightly; therefore, there are probably many different types of such clusters. This calculated binding also is supported by the EXAFS data. The overall electronic structure is similar to that observed in calculations for pure La2CuO4: the LaO planes remain ionic, even with the presence of the calcium dopant, and the Cu-O(1) bond is covalent. The calcium is ionic in character, with a net charge of 1.6, and the narrow Ca 3d band lies approx. 6 eV above the Fermi energy level.

AB - Quenched calcium-doped lanthanum cuprate (La2CuO4) samples were examined at room temperature using extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge spectroscopy (XANES) near the CaK edge, and via atomic- and electronic-structure modeling. Calculations and experiments show that the Ca atom, in a manner similar to that of Sr and Ba atoms, replaces the La atom and maintains its nine-fold coordination above the center of a CuO4 square, which is the nominal position of the La atom. In contrast to the Sr and Ba atoms, the distances from Ca to its nearest neighbors are similar to the size of the La3+ cation. The distances that are obtained from the simulation are in reasonable agreement with the experimental results for calcium, as well as previous studies that involved strontium and barium. The binding of a calcium dopant to vacancies on the O(1) sites is stable, but only slightly; therefore, there are probably many different types of such clusters. This calculated binding also is supported by the EXAFS data. The overall electronic structure is similar to that observed in calculations for pure La2CuO4: the LaO planes remain ionic, even with the presence of the calcium dopant, and the Cu-O(1) bond is covalent. The calcium is ionic in character, with a net charge of 1.6, and the narrow Ca 3d band lies approx. 6 eV above the Fermi energy level.

UR - http://www.scopus.com/inward/record.url?scp=0033189216&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033189216&partnerID=8YFLogxK

M3 - Article

VL - 82

SP - 2451

EP - 2459

JO - Journal of the American Ceramic Society

JF - Journal of the American Ceramic Society

SN - 0002-7820

IS - 9

ER -