The effects of calcination heating rate on phase formation and structure of zircon sand-derived zirconia

Phase formation and structure examination has been conducted to study the effects of thermal treatment and heating rates on zircon (ZrSiO 4 ) sand-derived zirconia (ZrO 2 ). A preliminary investigation of the elements present in the sand using XRF revealed that Zr was the major element, corresponding to 92.4% of the sample. The zirconia precursor was synthesized through a three-stage process that involves purifying zircon powder, alkali fusion, and co-precipitation method. The zirconia crystal was obtained by heating the sample to 700, 800 and 900 °C with heating rates of 5 and 10 °C/min, respectively. The formation of tetragonal zirconia (t-ZrO 2 ) with space group P42/nmc is shown in a qualitative study of all sample XRD patterns. Furthermore, Rietveld analysis was used to determine crystal structure parameters including lattice parameters and tetragonality. The calcination temperature and heating rate decide the phase, t-ZrO 2 crystallite size, and tetragonality. Furthermore, calcining to 700 and 800 °C created t-ZrO 2 , however, elevated temperature to 900 °C lead to t→m transformation. The t-ZrO 2 size increases with temperature between 700 and 900 °C, range of 9 and 15 nm. Meanwhile, the tetragonality of t-ZrO 2 tends to decrease due to m-ZrO 2 being present.