Fe- and Cr-substituted mullites: Mossbauer spectroscopy and Rietveld structure refinement

In the ternary La2O3-TiO2-ZrO2 system the subsolidus phase relations at 1350°C were determined using X-ray diffraction, scanning electron microscopy end energy dispersive X-ray analysis. The collected results are presented in the form of a phase diagram. In the equilibrium state there are 7 ternary and 5 binary compatible subsystems. In the system TiO2SS, ZrO2SS, ZrTiO4SS, La2Zr2O7ss and La2O3SS solid solutions were confirmed and La4Ti9O24 and La2Ti2O7ss solid solutions were identified. The addition of ZrO2 does not stabilize the La2/3TiO3 perovskite compound, nor the addition of TiO2 a highly temperature stable compound La2/3ZrO3.