EFFECT OF CO-DOPING La/Gd AND Y/Nd ON ELECTRICAL CHARACTERISTICS OF CERIA-BASED SOLID ELECTROLYTE SYSTEM

• Main Author: NUGROHO (NIM : 12514039), AGUNG
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25129
• Institution: Institut Teknologi Bandung

Rare earth element (REE) is one of a set 15 chemical elements lanthanides, as well as scandium and yttrium. One such form of REE utilization is as solid electrolyte in solid oxide fuel cell (SOFC). Conventional SOFCs operate at high temperatures (800-1000 oC) which causing many practical problems, such as high costs, limited sealing of material, material vulnerability, component degradation, and slow start-up and shut-off. Ceria-based solid oxide system has potential to operate at intermediate temperature (600-800 oC). Co-doping with REE into system has a positive impact on improving its electrical performance characteristics. <br /> <br /> In this research, ceria-based solid oxide system was prepared with co-dopants of La/Gd and Y/Nd with each composition is Ce0,7La(0,3-x)GdxO1,9 and Ce0,7Nd(0.3- x)YxO1,9. The ratio of Moles Y/Nd and Gd/La is varied from 0; 0.5; 1; up to 2. Preparation of powder is done by solid state reaction method which is then compacted with 40 kN force to form green pellets with diameter size 0.81 cm. Sintering was then performed at a temperature of 1400 oC for 5 hours. The dimensions of each sintering sample were measured to determine the relative density of each sample. Electrochemical impedance spectroscopy (EIS) test was performed using Potensiostat Gamry Instrument Ref. 600 in the operating temperature range 500-700 oC with temperature difference 50 oC each taking data. The EIS test results data were analyzed to determine the electrical characteristics of each sample. <br /> <br /> The equivalent electric circuit model of each sample generally consists of L-Rg- (Rgb/CPEgb)-(Rp3/CPE3), where L is an inductor, R is a resistor, and CPE is a constant of phase elements. The EIS analysis shows that the increase ratio in the addition of co-dopants into the solid electrolytic oxide system has a positive effect on the electrical characteristics of the system. The impedance decreases with the ratio addition of mole co-dopants. Then, ionic conductivity increases as ratio co-dopants increase. The smallest impedance is 42.2 &#937;.cm2 and the highest ionic conductivity is 1.0121 x 10-2 S.cm-2. Both values are generated by the sample Ce0,7La0,1Gd0,2O1,9 at a temperature of 700 oC. The activation energy decreases with increasing operating temperature. The lowest activation energy is owned by Ce0,7Nd0,1Y0,2O1,9 sample with value 0.9399 eV.