Two methods of elaborating Na5 Y Si4, O12 type ceramics are described: a solid state reaction between SiO2, Y2O3, Na2CO3 and NH4H2PO4 at 1020°C and a "sol-gel" preparation process at room temperature. Characterization of the prepared materials was carried out using various techniques: XR, IR TG and DTA. Ceramic samples Na5-x Y Si4-X Px O12 have been synthetised. The rate of a secondary phase (Na3 Y Si3 Y Si3O9) increases with x. Addition of 1 to 2% of NaF or LiF decreases the amount of the later phase. Ignittion of the gel at different temperature leads to Na, Y Si3O9 at 500 °C, whereas Na5 Y Si4 O12 becomes visible at 700 °C and preponderant near 900 °C.
N. Fakhar-Bourguiba, L. Smiti-Dogguy, N. Gharbi