Production of Apatite-type Oxide Ion Conductors La9.33Si6O26 andLa9.33Si2Ge4O26 by Mechanical Alloying

摘要

In this work, apatite-type La9.33Si6O26 phase was synthesized by mechanical alloying at roomrntemperature. The influence of partial substitution of Si by Ge on the formation of the apatitetypernLa9.33Si2Ge4O26 phase was also studied. Powders of La2O3, GeO2 and SiO2 were dryrnmilled in a planetary ball milling at increasing rotation speeds of 150, 250 and 350 rpm andrnmilling times up to 50 h. Single La9.33Si6O26 and La9.33Si2Ge4O26 phases were obtained duringrnmechanical alloying at high rotation speed. The higher the rotation speed the lower was therntime required for the lanthanum silicate and lanthanum germanosilicate phases formation.rnEven so single phase apatite-type lanthanum silicate and germanosilicate are obtained afterrnsintering, with a high degree of crystallinity, an important quantity of pores still exists afterrnsintering (about 20-25% according to porosimetry results).The incorporation of Ge in thernapatite-type structure has no obvious influence on the consolidation and sintering processes.rnBoth, the structure and the densification degree of the samples manufactured with andrnwithout Ge are very similar.