Physicochemical properties of single phase La ₂Zr ₂O ₇ powder

Powders of La ₂O ₃ and ZrO ₂ in ethanol based suspension were planetary ball milled at 200 rpm for 12 hours, dried and then heat treated at 1500°C for one hour to synthesize single phase of La ₂Zr ₂O ₇ which is a very promising thermal barrier coating material. Planetary milling results to particle diminution together with an increase in surface area with increasing milling time as investigated by FE-SEM, particle size analyses and BET method. The formation of single phase La ₂Zr ₂O ₇ with pyrochlore structure was confirmed by X-ray diffraction and TEM analyses. DSC investigation on the milled powders revealed the dehydroxylation reaction at around 320°C and complete disintegration of ethanol including decarboxylation at around 500°C. The absence of these peaks in the thermal plot for the single phase material confirms its thermal stability at 1500°C sintering temperature.