In this work, powders of La2O3 and SiO2 were
mechanically alloyed in a
planetary ball mill with different rotation speeds (150-350 rpm) for maximum periods
of time of 50 h and subsequently compacted at room temperature by cold isostatic
pressure (CIP). Finally, the samples were sintering at temperatures up to 1300 °C in
The results showed that a higher rotation speed decreases the time required to the formation of the La9.33(SiO4)6O2 phase. Single phase powders of La9.33(SiO4)6O2 were obtained with 350 and 250 rpm after 15 and 50 h milling, respectively. No reaction between the La2O3 and SiO2 powders occurred with 150 rpm milling even during 50 h processing. For the milled samples with incomplete reaction the single La9.33(SiO4)6O2 phase is obtained at temperatures between 900 °C and 1300 °C, depending on the mechanical alloying parameters.
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