Investigation into the effect of structural change on oxygen sensing properties due to hot spot phenomena of Pr3+ substituted EuCBa^Pr^CusO™ (x = 0.00, 0.05, 0.25, and 0.40) ceramic rods. / Muhamad Faizal Othman

A hot spot which is a local area glowing orange appear in Eu(Bai.xPrx)2Cu307^ when a certain voltage is applied to the rod which heats up due to Joule's heating. The effect of structural change and hole concentration due to Pr3+ substitution based Eul23 were investigated. In this experiment, the Eu(Ba].xPrx)2Cu307^ (x = 0.00, 0.05, 0.25, and 0.40) ceramic samples were synthesized using conventional solid state method. The powder were prepared in stoichiometric ratio, mixed and ground. The powders were then calcined and press into pellets and sintered. The pellet was cut into rods that have dimensions of 13 mm x 0.65 mm x 0.65 mm. The structure changes from orthorhombic to pseudo-tetragonal at x = 0.25 and x = 0.40. The current through the rod decreased abruptly after the hot spot appeared with increasing voltage for samples x = 0.00 and x - 0.05. However, for the x - 0.25 sample showed constant current plateau with increasing voltage and displayed better stability and repeatability compared to x = 0.00 and 0.05 samples. In addition, all the samples show increased sensitiveness at lower p02 concentration for p02 between 20% to 100%. From the result, it is suggested that the structural changes from orthorhombic to tetragonal due to the Pr substitution in particular for sample x > 0.25 resulted in an improved oxygen sensing properties.