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powder synthesis and sintering studies of yttria doped barium zirconate
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POWDER SYNTHESIS &
SINTERING STUDIESOF
YTTRIA DOPED BARIUM ZIRCONATE
CONTENTSDoped Barium ZirconateApplications, advantages & disadvantages of
BZYSinteringSample PreparationCharacterizationResults and DiscussionConclusion
BARIUM ZIRCONATEPervoskite structure
When Barium Zirconate (BZ) is doped with Y2O3, oxygen vacancies are formed.
Y2O3 + BaZrO3 2YZr’ + 3Oo
x + Vooo
APPLICATIONS OF BZY
It is used as electrolyte and electrode material in Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC).
ADVANTAGES OF BZY
High stability with sufficient proton conductivity in the temperature range of 600-800o C
Greatly reduces material & fabrication problems
Improves cell reliability during prolonged operations
Stable in CO2 and H2O containing atmosphere
DISADVANTAGES OF BZY
Yttria doped barium zirconate material is difficult to sinter
SINTERING
Sintering simply means “coalescence of powder at elevated temperatures.”
The driving force operating during sintering is the reduction in surface energy.
SINTERING
Various atomic mechanisms:1. Evaporation – Condensation (path 1)2. Surface diffusion (path 2)3. Volume diffusion (path 3)4. Grain boundary diffusion (path 4)
SINTERING STAGESAn interval of geometric change in which pore shape is
totally defined (such as rounding of necks during the initial stage sintering) or an interval of time during which the pore remains constant in shape while decreasing in size
SAMPLE PREPARATION
Solid-state method Raw materials: BaCO3 , ZrO2 , Y2O3
Weighing and mixing/grindingCalcinationPelletization (uniaxial and cold isostatic
pressing)Solid state sintering
CHARACTERIZATION
Phase formationDensitySinteringMicrostructural studies
RESULTS & DISCUSSIONS1. XRD
20 30 40 50 600
50
100
150
200
1300 1350 1400
Inte
nsi
ty (
A.U
)
2
RESULTS & DISCUSSIONS2. PARTICLE MORPHOLOGY & PARTICLE SIZE DISTRIBUTION
Shape not exactly sphericalParicle size varied from 0.205 µm to 1.405 µmAverage particle size 0.649 µm
RESULTS & DISCUSSIONS3. SINTERING
Dilatometry
maximum shrinkage was 5.36 % at 1556o C
0 700 1400-6
-4
-2
0
Shr
imka
ge (i
n %
)
Temperature (in OC)
Temperature Vs Shrinkage
RESULTS & DISCUSSIONS3.SINTERING
Densification
Low densityGrain size was 200 – 500 nmSingle phase formation had taken place
RESULTS & DISCUSSIONS4. DENSIFICATION USING ZnO
By using ZnO, 92 – 94 % density was obtained.
CONCLUSION
Single phase formation BZY couldn’t be sintered properly even at
1550o CZnO helps in sintering
THANK YOU!!!
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