Regularities of formation of aluminium and gallium garnets of REE(Y) and their scandium-substituted derivatives

The mechanism of formation of binary and Sc-substituted aluminium and gallium garnets of REE(Y) by solid-phase synthesis from oxide mixture and by the precipitation method from salt solution is investigated by the methods of micro X-ray spectral, complex thermal and X-ray phase analyses. It is established that interaction of rare earth oxides with Al2O3(Ga2O3) occurs due to advantageous diffusion of Al(Ga) into Ln2O3. Multistage reactions of compound formation with the garnet structure during solid phase synthesis as well as dependence of the intermediate product composition on REE nature are shown. Application of the joint precipitation method permitted to decrease the temperature of synthesis of the given cxompounds by 400-500 deg C and to prepare homogeneous fine dispersed mixture. Limits of isomorphic substitution for Sc3+ in the system studied are found. 46 refs.; 13 figs.; 6 tabs