High-temperature in-situ XRD measurements on homogenized starting powder mixtures were performed using the Cu Kα XRDynamic 500 diffractometer (equipped with a Pixos 2000 detector) and the heating chamber HTK 1500 (Anton Paar). Samples were heated at a rate of 5 °C/min and were held at each temperature for the measurement time of 61 min for the angular range between 15 ° and 70 ° 2𝜃 with a step size of 0.01°. Two series of in-situ measurements were performed: the first series was used to record diffractograms between 600 °C and 1200 °C in 50 °C steps, while the second series included measurements at 300 °C, 600 °C, between 800 °C and 1100 °C in 25 °C steps, and between 1100 °C and 1400 °C in 50 °C steps.