JP Journal of Heat and Mass Transfer
Volume 11, Issue 1, Pages 93 - 107
(February 2015) http://dx.doi.org/10.17654/JPHMTFeb2015_093_107 |
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OXYGEN SENSING BEHAVIOUR OF Pr DOPED CERAMIC RODS WITH HOT-SPOT
M. I. Adzam, M. I. M. Yusof and A. K. Yahya
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Abstract: In this study, 0.05, 0.10, and ceramic rectangular rods were prepared by the solid-state reaction method to investigate the effect of Pr doping on oxygen sensing behaviours. X-ray powder diffraction analysis showed all rods were orthorhombic in structure with reduction in orthorhombicity upon doping. For all samples, the I-V curve showed a relatively constant output current after the appearance of hot-spot. The magnitude of the constant output current was observed to be decreasing with increasing Pr doping which indicates possible reduction in intrinsic hole concentration. In addition, the output current for rods with 0.05 and 0.10 showed a sudden drop upon the appearance of hot-spot, due to the sudden increase in hot-spot temperature, before becoming slightly constant. However, the sudden drop of output current upon appearance of hot-spot was not observed when Pr was increased to and 0.20 but instead a stable output current was observed. Interestingly, the output current after appearance of hot-spot for all rods showed strong dependency on ambient oxygen concentration. The sensitivity for each rod, however, reduces with increasing ambient oxygen concentration. The doping seems to prevent the sensitivity from dropping to almost zero as was previously reported for rods due to existence of Cu-O chains in the orthorhombic structure. Pr doping has also resulted in better oxygen absorption response time and better output current stability compared to other rods. |
Keywords and phrases: powders, solid state reaction, hot-spot rods, Eu123, Pr substitution, oxygen sensors. |
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