Synthesis and characterization of LaPO4-coated α-Al2O3 powders

LaPO4-coated α-Al2O3 powders were successfully synthesized through the heterogeneous precipitation method. The coated powders were characterized by XRD, TEM, EDS, and zeta-potential measurements. According to the XRD results, the coated powders consisted of only α-Al2O3 and monoclinic LaPO4. The TEM examinations and EDS analysis showed that under alkaline condition a homogeneous coating with thickness of ∼10 nm was obtained on the α-Al2O3 powder surface. The zeta-potential measurements showed the coated powders to have a pH value of 7.85 at isoelectric point, similar to that of LaPO4 (pH value of 8.21). This was in good agreement with the TEM and EDS results, indicating a successful coating process in our experiment.