Temperature and Molarity Effects on the Synthesized Zircon Crystal Cells

A study was carried out on the effect of hydrochloric acid (HCl) temperature and molarity during the dissolution process on the crystal cell of ZrSiO4 of zircon powders derived from zircon sand mined in Kereng Pangi, Central Kalimantan. The study is a continuation of the previous workand is aimed at associating the process and structural parameters of the zircon phase in the product. The synthesis was started with a well-established route in our laboratory, i.e., magnetic separation and milling for 2 hours, but the subsequent leaching using the HCl step was carried out at varying temperatures and concentrations. The temperature variations used were 80oC, 90oC, and 100oC, while the molar variations of HCl were 0.5 and 2 M. Then, the various products were further leached using 7 M sodium hydroxide (NaOH) to yield zircon powders subjected to X-ray diffraction (XRD) investigation. The XRD data analysis using Rietica software found that at the concentration of 0.5 M, the increasing temperature decreased in zircon cell volume but increased the tetragonality parameter c/a. However, opposite results occurred at the concentration of 2 M HCl. In general, we found that the impurity levels in the zircon powders may be associated with its cell volume and tetragonality parameters, i.e., the more the quartz content in the zircon powder, the smaller the zircon cell volume and tetragonality.