Synthesis of Single Phase La₂Zr₂O₇ by Wet Mechanochemical Treatment

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Powders of La₂O₃ and ZrO₂ in ethanol based suspension were used as precursor materials for the wet mechanochemical (MC) synthesis of single phase La₂Zr₂O₇, a promising thermal barrier coating (TBC) material. Lanthania powder was first preheated at 1200°C prior to MC treatment in a planetary ball mill at 200, 300 and 400 revolutions per minute (rpm) milling speeds for 12, 18, and 24 hours using zirconia pot and balls. The slurries were then dried at 110°C for 24 hours in an oven followed by heat treatment at 1500°C for 1 hour. X-ray diffraction results showed that single phase La₂Zr₂O₇ was produced using 5 mm ball at 200 rpm milling for 12 hours and using 10 mm balls at 400 rpm for 24 hours. Smaller grinding balls and slower milling speed allowed more homogeneous mixing during wet mechanochemical treatment in a 250 mL milling pot. The average particle size of the products is lower than 1.8 μm. The yield of powder is greater than 98%.