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Title: Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

Abstract

Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce 0.9Gd 0.1O 1.95, and to evaluate whether they could be used to produce dense, constrained Ce 0.9Gd 0.1O 1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce 0.9Gd 0.1O 1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce 0.9Gd 0.1Omore » 1.95 indicated that lithium affects sintering by producing a Li 2O-Gd 2O 3-CeO 2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.« less

Authors:
 [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
926303
Report Number(s):
LBNL-63298
R&D Project: 512601; BnR: KC0201020; TRN: US200807%%635
DOE Contract Number:
AC02-05CH11231
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; CERIUM; DEPOSITION; ELECTROLYTES; GADOLINIUM OXIDES; GRAIN BOUNDARIES; LITHIUM; LITHIUM NITRATES; PELLETS; SINTERING; SOLID OXIDE FUEL CELLS; STAINLESS STEELS; SUBSTRATES

Citation Formats

Nicholas, Jason Dale. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications. United States: N. p., 2007. Web. doi:10.2172/926303.
Nicholas, Jason Dale. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications. United States. doi:10.2172/926303.
Nicholas, Jason Dale. Mon . "Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications". United States. doi:10.2172/926303. https://www.osti.gov/servlets/purl/926303.
@article{osti_926303,
title = {Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications},
author = {Nicholas, Jason Dale},
abstractNote = {Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce0.9Gd0.1O1.95, and to evaluate whether they could be used to produce dense, constrained Ce0.9Gd0.1O1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce0.9Gd0.1O1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce0.9Gd0.1O1.95 indicated that lithium affects sintering by producing a Li2O-Gd2O3-CeO2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.},
doi = {10.2172/926303},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Thesis/Dissertation:
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  • Coal is the United States’ most widely used fossil fuel for the production of electric power. Coal’s availability and cost dictates that it will be used for many years to come in the United States for power production. As a result of the environmental impact of burning coal for power production more efficient and environmentally benign power production processes using coal are sought. Solid oxide fuel cells (SOFCs) combined with gasification technologies represent a potential methodology to produce electric power using coal in a much more efficient and cleaner manner. It has been shown in the past that trace speciesmore » contained in coal, such as sulfur, severely degrade the performance of solid oxide fuel cells rendering them useless. Coal derived syngas cleanup technologies have been developed that efficiently remove sulfur to levels that do not cause any performance losses in solid oxide fuel cells. The ability of these systems to clean other trace species contained in syngas is not known nor is the effect of these trace species on the performance of solid oxide fuel cells. This works presents the thermodynamic and diffusion transport simulations that were combined with experimental testing to evaluate the effects of the trace species on the performance of solid oxide fuel cells. The results show that some trace species contained in coal will interact with the SOFC anode. In addition to the transport and thermodynamic simulations that were completed experimental tests were completed investigating the effect of HCl and AsH 3 on the performance of SOFCs.« less
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