Key words: yttrium aluminum garnet doped with cerium; stepwise synthesis, hydrothermal treatment, a supercritical water fluid, luminescence
In this paper a continuous stepwise method of fine crystalline yttrium aluminum garnet doped with cerium (YAG: Ce3+) synthesis in supercritical water (SCW) fluid is described. On the first step, the stoichiometric mixture of yttrium oxide and aluminum hydroxide is treated in a cerium nitrate water solutions at 280 °C and water vapor pressure 6.3 MPa. Then temperature and pressure are increased up to the values corresponding to the supercritical state of water (392 — 400 °C, 22 MPa). Cerium concentration in a water medium is varied from 0.012 to 0.706% calculated on the basis of the final synthesized garnet. Products obtained on different stages of the synthesis are studied using various physical methods. It is found that on the first stage, in hydrothermal conditions, intermediate products, namely boemite and yttrium hydroxide, and later — a poorly shaped YAG: Ce3+ are formed. On this stage, the incorporation of Ce cations from the reaction mixture into the semi-products is proceeding. Owing to this, on the second stage of the synthesis, in the SCW conditions we obtained the YAG: Ce3+— a material possessing a high emission at 528 nm. In the SCW conditions well-shaped crystals of 0.3—0.5 nm size and rhombohedral habit are formed.
doi:10.1134/S1990793111070025