Alfred University Research and Archive (AURA)

A Study on the Defect Chemistry of Barium-Strontium-Cobalt-Iron-Oxide System

Show simple item record

dc.contributor.advisor Edwards, Doreen Jung, Jae-Il 2017-02-07T15:23:58Z 2017-02-07T15:23:58Z 2010-07
dc.description Advisory committee members: Alastair Cormack, Scott Misture, Walter Schulze. Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Ceramics at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University en_US
dc.description.abstract BSCF, or Ba0.5Sr0.5Co0.8Fe0.2O3-δ, is a well known mixed electronic and ionic conductor (MEIC) that has been considered as potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Initial 4-point conductivity measurements of Ba0.5Sr0.5CoxFe1-xO3-δ (x = 0, 0.2, 0.4, 0.6, and 0.8) as a function of temperature in air were conducted with Pt-paste electrodes. Below 400oC, conductivity was thermally activated (Ea = 0.21 – 0.4eV). Above 400oC, conductivity decreased with increasing temperature, which was attributed to a decrease in p-type carriers resulting from the formation of oxygen vacancies associated with the reduction of Fe4+. The conductivity of BSCF (x = 0.8) as a function of pO2 was also measured. Above 400oC for pO2 > 0.01atm, the conductivity increased with increasing pO2, confirming p-type conduction. For pO2 < 0.01atm, a slight increase in conductivity with decreasing pO2 was observed. To further investigate the possibility of n-type conduction in BSCF at low pO2, the conductivity and thermopower simultaneously as a function of temperature and pO2 for five compositions of Ba0.5Sr0.5CoxFe1-xO3-δ (0 < x < 0.8) were measured. These measurements enable better understanding of the conduction mechanism of BSCF according to the changes of temperatures and oxygen partial pressures. With XPS analysis, as cobalt concentration increases, the trend of peak shifts in O1s and cations (Co, Fe) has been studied. This study provides the fundamental background of bonding state on the surface of BSCF ceramics. en_US
dc.format.extent 88 pages en_US
dc.language.iso en_US en_US
dc.publisher New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering. en_US
dc.relation.ispartof Scholes Library en_US
dc.rights.uri en_US
dc.title A Study on the Defect Chemistry of Barium-Strontium-Cobalt-Iron-Oxide System en_US
dc.type Thesis en_US

Files in this item

This item appears in the following Collection(s)

Show simple item record



My Account