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Title: Oxygen content and structures of La[sub 1-x]Ca[sub x]MnO[sub 3+d] as a function of synthesis conditions

Abstract

Using thermogravimetric analysis measurements, oxygen content was measured for La[sub 1[minus]x]Ca[sub x]MnO[sub 3+d] (0 [le] x [le] 0.38) samples prepared at high oxygen pressure. The oxygen content was found to decrease uniformly with increasing x for samples annealed at 12 and 140 atm O[sub 2] at 800 C, slowly cooled in 1, 20, and 100% O[sub 2], as well as for samples in thermal equilibrium at high temperatures of [approximately]1000--1400 C. Annealing at a specific temperature and oxygen pressure leads to approximately constant hole doping over an extended range of Ca substitution x. The most favorable synthesis conditions for obtaining stoichiometric, d = 0, samples were determined. The data suggest that several studies reported in the literature were done on significantly nonstoichiometric materials. Structural results show that, in addition to the orthorhombic Pbnm O[prime] (cla < [radical]2) and O* (a [approximately] b [approximately] c/[radical]2) structures, the rhombohedral R[bar 3]c structure is stabilized at high oxygen contents for x [le] 0.14. A sequence of observed structures and a decrease of the unit cell volume with increasing d confirm that the additional holes are doped uniformly by cation-vacancy defects for all studied x.

Authors:
; ;  [1];  [2];  [3]
  1. (Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics)
  2. (Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics Polish Academy of Sciences, Wroclaw (Poland). Inst. of Low Temperature and Structure Research)
  3. (Argonne National Lab., IL (United States). Materials Science Div.)
Publication Date:
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6105415
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 146:2; Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALCIUM OXIDES; CRYSTAL STRUCTURE; EXPERIMENTAL DATA; LANTHANUM OXIDES; MANGANESE OXIDES; STOICHIOMETRY; SYNTHESIS; TEMPERATURE DEPENDENCE; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION; ALKALINE EARTH METAL COMPOUNDS; CALCIUM COMPOUNDS; CHALCOGENIDES; CHEMICAL ANALYSIS; COHERENT SCATTERING; DATA; DIFFRACTION; GRAVIMETRIC ANALYSIS; INFORMATION; LANTHANUM COMPOUNDS; MANGANESE COMPOUNDS; NUMERICAL DATA; OXIDES; OXYGEN COMPOUNDS; QUANTITATIVE CHEMICAL ANALYSIS; RARE EARTH COMPOUNDS; SCATTERING; THERMAL ANALYSIS; TRANSITION ELEMENT COMPOUNDS; 360202* - Ceramics, Cermets, & Refractories- Structure & Phase Studies; 360201 - Ceramics, Cermets, & Refractories- Preparation & Fabrication

Citation Formats

Dabrowski, B., Dybzinski, R., Chmaissem, O., Bukowski, Z., and Jorgensen, J.D. Oxygen content and structures of La[sub 1-x]Ca[sub x]MnO[sub 3+d] as a function of synthesis conditions. United States: N. p., 1999. Web. doi:10.1006/jssc.1999.8389.
Dabrowski, B., Dybzinski, R., Chmaissem, O., Bukowski, Z., & Jorgensen, J.D. Oxygen content and structures of La[sub 1-x]Ca[sub x]MnO[sub 3+d] as a function of synthesis conditions. United States. doi:10.1006/jssc.1999.8389.
Dabrowski, B., Dybzinski, R., Chmaissem, O., Bukowski, Z., and Jorgensen, J.D. Wed . "Oxygen content and structures of La[sub 1-x]Ca[sub x]MnO[sub 3+d] as a function of synthesis conditions". United States. doi:10.1006/jssc.1999.8389.
@article{osti_6105415,
title = {Oxygen content and structures of La[sub 1-x]Ca[sub x]MnO[sub 3+d] as a function of synthesis conditions},
author = {Dabrowski, B. and Dybzinski, R. and Chmaissem, O. and Bukowski, Z. and Jorgensen, J.D.},
abstractNote = {Using thermogravimetric analysis measurements, oxygen content was measured for La[sub 1[minus]x]Ca[sub x]MnO[sub 3+d] (0 [le] x [le] 0.38) samples prepared at high oxygen pressure. The oxygen content was found to decrease uniformly with increasing x for samples annealed at 12 and 140 atm O[sub 2] at 800 C, slowly cooled in 1, 20, and 100% O[sub 2], as well as for samples in thermal equilibrium at high temperatures of [approximately]1000--1400 C. Annealing at a specific temperature and oxygen pressure leads to approximately constant hole doping over an extended range of Ca substitution x. The most favorable synthesis conditions for obtaining stoichiometric, d = 0, samples were determined. The data suggest that several studies reported in the literature were done on significantly nonstoichiometric materials. Structural results show that, in addition to the orthorhombic Pbnm O[prime] (cla < [radical]2) and O* (a [approximately] b [approximately] c/[radical]2) structures, the rhombohedral R[bar 3]c structure is stabilized at high oxygen contents for x [le] 0.14. A sequence of observed structures and a decrease of the unit cell volume with increasing d confirm that the additional holes are doped uniformly by cation-vacancy defects for all studied x.},
doi = {10.1006/jssc.1999.8389},
journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = ,
volume = 146:2,
place = {United States},
year = {1999},
month = {9}
}