Electrical conductivity of zirconia and yttrium-doped zirconia from Indonesian local zircon as prospective material for fuel cells

Study of the Synthesis of Zirconia Powder from Zircon Sand obtained from Zircon Minerals Malaysia by Caustic Fusion Method

“…The material was prepared using zircon sand and produced at a pH of 10 when the precipitation was formed, which means it was able to obtain a high percentage of monoclinic form. A medium pH range (8-11) could produce monoclinic zirconia, while a low pH (3-5) and high pH range (13)(14) produces tetragonal phase based on previous researches [15]. This is because the initial zirconium species are well detached, Fig 3. Zirconia phase transformations.…”

“…Based on the DSC curves, the melting point of ZrO(OH)2 was 59.94 °C. The melting point of ZrO(OH)2 should be 318 °C [13]. This result showed that the presence of impurity components added during the synthesis of ZrO(OH)2, such as ammonium ion, had accelerated the degradation of the polymeric network, while the chloride ions that had affected the thermal stability of caustic fusion were not significant, compared to the ammonium ions.…”

“…The zirconia was synthesized by using the caustic fusion method. NaOH was weighed at 30 g and zircon at 33 g [13]. The weight was determined by calculating the number of moles according to the chemical reaction below […”

“…The Zr(OH)2 was produced after 24 h, and then filtered and washed using hot water to get a pH solution of 7 . Before the zirconia powder was obtained by the calcination process, the residue was heated at 150 °C for 3 h to remove the moisture content [13].…”

“…Within the temperature of 1170 to 2300 °C, the zirconia was in a stable tetragonal form [19][20]. The effect of pH can be the main factor for the zirconia produced in the tetragonal phase because it can be obtained at either a low pH (3)(4)(5) or high pH (13)(14) range [15].…”