In-situ Synchrotron Radiation XRD Crystal Structure and Microstructure Analysis of CaO-ZrO₂ solid-solution at 1100°C with Prolonged Heating

The structural analysis of the CaO-ZrO 2 solid-solutions was carried out using in-situ synchrotron radiation X-ray diffraction (SR-XRD). CaO-ZrO 2 solid-solutions with 0, 2.5, and 5 at.% CaO contents were synthesized via a solid-solid ball milling technique. The amorphous ZrO 2 powder was synthesized via co-precipitation using ZrCl 4 and NH 4 OH as precursors, while the CaO powder was purified from a local limestone. In-situ SR-XRD measurements were conducted on the CaO-ZrO 2 mixtures by independently heating them to 1100°C for different holding times of 0, 12, 24, and 36 minutes using a DHS furnace. Qualitative analysis of all SR-XRD patterns showed that only tetragonal zirconia (t-ZrO 2 ) was present. The crystallite size of tetragonal zirconia ranged from 17 to 22 nm, depending on calcination holding time and CaO addition. Further analysis showed that the tetragonality ( c/a ) parameter remained relatively constant over the 36-minute holding time. However, the introduction of CaO led to an insignificant reduction in tetragonality, averaging 0.292%.