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Title: Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature

Abstract

The chemical stability of lanthanide nickelates Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) has been studied in the temperature range 25–1300 °C, either in air or at low pO{sub 2} (down to 10{sup −4} atm). Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterization have shown that all compounds retain their K{sub 2}NiF{sub 4}-type structure in these conditions, while remaining over-stoichiometric in oxygen up to 1000 °C. Only Nd{sub 2}NiO{sub 4+δ} starts to decompose into Nd{sub 2}O{sub 3} and NiO above 1000 °C, at pO{sub 2}=10{sup −4} atm. In addition, a careful analysis of the lanthanide nickelates structural features has been performed by in situ XRD, as a function of temperature and pO{sub 2}. For all compounds, a structural transition has been always observed in the temperature range 200–400 °C, in air or at pO{sub 2}=10{sup −4} atm. In addition, their cell volume did not vary upon the variation of the oxygen partial pressure. Therefore, these materials do not exhibit a chemical expansion in these conditions, which is beneficial for a fuel cell application as cathode layers. Additional dilatometry measurements have revealed that a temperature as high as 950 °C for Pr{sub 2}NiO{sub 4+δ} or 1100 °C formore » La{sub 2}NiO{sub 4+δ} and Nd{sub 2}NiO{sub 4+δ} has to be reached in order to begin the sintering of the material particles, which is of primary importance to obtain an efficient electronic/ionic conduction in the corresponding designed cathode layers. Besides, excellent matching was found between the thermal expansion coefficients of lanthanide nickelates and SOFC electrolytes such as 8wt% yttria stabilized zirconia (8YSZ) or Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} (GDC), at least from 400 °C up to 1400 °C in air or up to 1200 °C at pO{sub 2}=10{sup −4} atm. - Graphical abstract: This study reports the good chemical stability of oxygen overstoichiometric Ln2NiO4+δ(Ln = La, Pr or Nd) at high temperatures (up to 1300 °C), eitherin air or at pO2down to 10-4 atm. In addition, these MSC cathode materials show a small chemical expansion as well as a good TEC compatibility with electrolyte materials (GDC or YSZ). - Highlights: • The structure of Ln2NiO4+δ compounds are studied vs. temperature and pO2 • Structural transitions are evidenced in air as well as in low pO2 atmosphere • The structural transitions do not significantly affect their TECs values • Up to 1200 °C, they show good chemical stability and no chemical expansion vs. pO2 • TECs of nickelates, 8YSZ and GDC are compared in air and in low pO2 atmosphere.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
OSTI Identifier:
22486736
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 228; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATMOSPHERES; DILATOMETRY; GRAVIMETRY; LANTHANUM COMPOUNDS; LAYERS; NEODYMIUM OXIDES; NICKEL OXIDES; NICKELATES; PARTIAL PRESSURE; PRASEODYMIUM COMPOUNDS; PRESSURE DEPENDENCE; SINTERING; SOLID OXIDE FUEL CELLS; STOICHIOMETRY; TEMPERATURE DEPENDENCE; THERMAL EXPANSION; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION; YTTRIUM OXIDES; ZIRCONIUM OXIDES

Citation Formats

Flura, Aurélien, Dru, Sophie, Nicollet, Clément, Vibhu, Vaibhav, Fourcade, Sébastien, Lebraud, Eric, Rougier, Aline, Bassat, Jean-Marc, and Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr. Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature. United States: N. p., 2015. Web. doi:10.1016/J.JSSC.2015.04.029.
Flura, Aurélien, Dru, Sophie, Nicollet, Clément, Vibhu, Vaibhav, Fourcade, Sébastien, Lebraud, Eric, Rougier, Aline, Bassat, Jean-Marc, & Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr. Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature. United States. doi:10.1016/J.JSSC.2015.04.029.
Flura, Aurélien, Dru, Sophie, Nicollet, Clément, Vibhu, Vaibhav, Fourcade, Sébastien, Lebraud, Eric, Rougier, Aline, Bassat, Jean-Marc, and Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr. Sat . "Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature". United States. doi:10.1016/J.JSSC.2015.04.029.
@article{osti_22486736,
title = {Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature},
author = {Flura, Aurélien and Dru, Sophie and Nicollet, Clément and Vibhu, Vaibhav and Fourcade, Sébastien and Lebraud, Eric and Rougier, Aline and Bassat, Jean-Marc and Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr},
abstractNote = {The chemical stability of lanthanide nickelates Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) has been studied in the temperature range 25–1300 °C, either in air or at low pO{sub 2} (down to 10{sup −4} atm). Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterization have shown that all compounds retain their K{sub 2}NiF{sub 4}-type structure in these conditions, while remaining over-stoichiometric in oxygen up to 1000 °C. Only Nd{sub 2}NiO{sub 4+δ} starts to decompose into Nd{sub 2}O{sub 3} and NiO above 1000 °C, at pO{sub 2}=10{sup −4} atm. In addition, a careful analysis of the lanthanide nickelates structural features has been performed by in situ XRD, as a function of temperature and pO{sub 2}. For all compounds, a structural transition has been always observed in the temperature range 200–400 °C, in air or at pO{sub 2}=10{sup −4} atm. In addition, their cell volume did not vary upon the variation of the oxygen partial pressure. Therefore, these materials do not exhibit a chemical expansion in these conditions, which is beneficial for a fuel cell application as cathode layers. Additional dilatometry measurements have revealed that a temperature as high as 950 °C for Pr{sub 2}NiO{sub 4+δ} or 1100 °C for La{sub 2}NiO{sub 4+δ} and Nd{sub 2}NiO{sub 4+δ} has to be reached in order to begin the sintering of the material particles, which is of primary importance to obtain an efficient electronic/ionic conduction in the corresponding designed cathode layers. Besides, excellent matching was found between the thermal expansion coefficients of lanthanide nickelates and SOFC electrolytes such as 8wt% yttria stabilized zirconia (8YSZ) or Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} (GDC), at least from 400 °C up to 1400 °C in air or up to 1200 °C at pO{sub 2}=10{sup −4} atm. - Graphical abstract: This study reports the good chemical stability of oxygen overstoichiometric Ln2NiO4+δ(Ln = La, Pr or Nd) at high temperatures (up to 1300 °C), eitherin air or at pO2down to 10-4 atm. In addition, these MSC cathode materials show a small chemical expansion as well as a good TEC compatibility with electrolyte materials (GDC or YSZ). - Highlights: • The structure of Ln2NiO4+δ compounds are studied vs. temperature and pO2 • Structural transitions are evidenced in air as well as in low pO2 atmosphere • The structural transitions do not significantly affect their TECs values • Up to 1200 °C, they show good chemical stability and no chemical expansion vs. pO2 • TECs of nickelates, 8YSZ and GDC are compared in air and in low pO2 atmosphere.},
doi = {10.1016/J.JSSC.2015.04.029},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 228,
place = {United States},
year = {Sat Aug 15 00:00:00 EDT 2015},
month = {Sat Aug 15 00:00:00 EDT 2015}
}
  • Reaction of several lanthanide trichlorides LnCl{sub 3} (Ln = La, Nd, Er, Lu) with 3 or 4 equiv of potassium 2,6-diisopropylphenoxide in THF solution leads to the formation of potassium salts of formula K[Ln(O-2,6-i-Pr{sub 2}C{sub 6}H{sub 3}){sub 4}][Ln = Nd (5), Er (6), Lu (7), La (8)]. These salts exhibit unusual solid-state structures involving multihapto potassium-{pi}-arene interactions. Not all lanthanide trichlorides produce the potassium salt directly from this reaction, and the nature of the product appears to be related to the solubility of the LnCl{sub 3} starting material in THF solution. Compounds 5 and 6 exist in the solid statemore » as pseudo-one-dimensional infinite-chain structures featuring multihapto K-C interactions with phenyl rings from two adjacent [Ln(OAr){sub 4}]{sup {minus}} units. Compound 8 forms a pseudo-two-dimensional sheet structure, with multihapto K-C interactions linking three neighboring [Ln(OAr){sub 4}]{sup {minus}} units. Ln-O distances within the tetrahedral [Ln(OAr){sub 4}]{sup {minus}} units average 2.211(12) (5), 2.084(14) (6) and 2.253-(6) {angstrom} (8).« less
  • A Transmission Electron Microscope (TEM) study of the oxygen excess Ln{sub 2}NiO{sub 4+{delta}} (Ln = La, Nd) compounds shows long range ordering of interstitial oxygen, characterized by weak superlattice reflections whose modulation wave-vector can be both commensurate as well as incommensurate with respect to the reciprocal lattice of the basic K{sub 2}NiF{sub 4} structure type for both oxides. The excess interstitial oxygen atoms are sometimes found to be rather mobile and susceptible to electron beam irradiation, although less so in the case of the Nd compound. A new type of superstructure has been found in the Nd case, and amore » model for the oxygen interstitial ordering is given.« less
  • The orthorhombic crystal structures of the series of Ln{sub 4-x}In{sub 5-y}S{sub 13} (Ln=La, Ce, Pr and Nd; x=0.08-0.12, y=0.21-0.24) compounds were investigated by means of X-ray crystal diffraction. The crystals of La{sub 3}In{sub 1.67}S{sub 7} and Gd{sub 3}InS{sub 6} were also obtained unexpectedly from the La-In-S and Gd-In-S systems and no respective Gd{sub 4-x}In{sub 5-y}S{sub 13} was obtained. In the structures of the orthorhombic Ln{sub 4-x}In{sub 5-y}S{sub 13} series and hexagonal La{sub 3}In{sub 1.67}S{sub 7} indium atoms occupy disordered positions in the octahedral and trigonal antiprismatic arrangement of the sulphur atoms. The crystal structure of the La{sub 4}Ag{sub 2}In{sub 4}S{submore » 13} is also given and discussed as an example of quaternary sulphide related to a ternary La-In sulphide. - Graphical abstract: In the series of the Ln{sub 4-x}In{sub 5-y}S{sub 13} (Ln=La, Ce, Pr and Nd; x=0.08-0.12, y=0.21-0.24) compounds the indium atoms occupy disordered position in the octahedral arrangement of the sulphur atoms. The tetrahedral position is ordered.« less
  • Crystal structures of Ln[sub 2](OH)[sub 2](CrO[sub 4])[sub 2] (Ln = Gd, Tb) and Ln[sub 3](OH)(CrO[sub 4])[sub 4] 3.5H[sub 2]O (Ln = Pr, Nd) were determined by a conventional single-crystal X-ray diffraction technique. Crystals of Ln[sub 2](OH)[sub 2] (CrO[sub 4])[sub 2](Ln = Gd, Tb) are monoclinic, space group P2[sub 1]/c (no.14). In Ln[sub 3](OH)(CrO[sub 4])[sub 4] 3.5H[sub 2]O (Ln = Pr, Nd) the coordination polyhedron of the nine oxygen atoms around Ln atoms is a tricapped trigonal prism. In Ln[sub 2](OH)[sub 2](CrO[sub 4])[sub 2] (Ln = Gd, Tb) the coordination polyhedron of the eight oxygen atoms around Ln atoms is amore » square antiprism. Structures form a three-dimensional network. Thermal behavior was investigated and IR spectra were recorded for Pr[sub 3](OH)(CrO[sub 4]) 3.5H[sub 2]O and Gd[sub 2](OH)[sub 2](CrO[sub 4])[sub 2]. Thermal decomposition of Pr[sub 3](OH)(CrO[sub 4])[sub 4] 3.5H[sub 2]O begins by the loss of water molecules and follows by the mechanism described for Yb[sub 2](OH)[sub 2](CrO[sub 4])[sub 2] and Ln[sub 2](CrO[sub 4])[sub 3] 7H[sub 2]O (Ln = La, Pr, Nd, Sm, Eu, Gd).« less
  • Reaction of lanthanum, cerium, or neodymium metals with 3/2 equiv of iodine in 2-propanol leads to formation of the alcohol adducts LnI{sub 3}(HO-i-Pr){sub 4} (Ln = La (1), Ce (2), Nd (3)) in good yield. Reaction of thorium metal turnings with 2 equiv of iodine in 2-propanol produces the dimeric halide-alkoxide complex Th{sub 2}I{sub 4} (O-i-Pr){sub 4}(HO-i-Pr){sub 2}(4). The molecular structures of 1,2 and 4 have been determined by means of single-crystal X-ray diffraction studies.