Phase equilibrium investigations and thermodynamic modeling of the HfO2–Ta2O5 system

Abstract

AbstractThe HfO2–Ta2O5 system was investigated using two distinct methods: the equilibration method at temperatures ranging from 1 573 to 1 873 K and the differential thermal analysis method up to 2 473 K. To identify the phases, X‐ray diffraction (XRD) and scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM/EDX) were employed. The temperature of the eutectic reaction L→Hf6Ta2O17+Ta2O5 was measured to be 2 052 K and the eutectic composition to be 66.7 mol.% Ta2O5. The peritectic reaction L+HfO2→Hf6Ta2O17 was observed at a temperature of 2 287 K. The heat capacity of the Hf6Ta2O17 phase was measured using differential scanning calorimetry from 240 to 1 300K. The thermodynamic database for the HfO2–Ta2O5 system was derived.