Effect of complex Si4++Mg2+ additive on sintering and properties of undoped YAG ceramics

The paper is devoted to studying of Si4++Mg2+ complex additive for obtaining transparent YAG ceramics for laser applications. Ceramics were fabricated by reactive vacuum sintering of commercial Y2O3, Al2O3 powders taken in a stoichiometric mixture with TEOS and MgO as sintering aids. Microstructure and optical properties of YAG:Si4+,Mg2+ ceramics were investigated as a function of the Si4+/Mg2+ ratio. It was found that the influence of complex additive does not correspond to the direct superposition of known Si4+- and Mg2+-induced sintering mechanisms and involves interaction between Si4+ and Mg2+ ions during sintering. It was shown that CSi/CMg> 1 provides more effective pore elimination and uniform microstructure when CSi/CMg< 1 gives more intense inhibition of grain grown which may be important for scaling the size of ceramics.