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Transparent(Er,Yb)-α-Sialon ceramics were fabricated by hot press sintering.Erbium and ytterbium were added as interstitial stabilizer to obtain α-Sialon.Erbium stabilized α-Sialon ceramics shows better transparency as well as upconversion luminescence.Yb2O3 was co-doped with Er2O3 but there was no effect of ytterbium as a sensitizer on upconversion luminescence.Yb3+ ion has smaller cationic radius than Er3+,the Yb3+ ion is much preferred over Er3+ to stabilize the α-Sialon phase.Thus,poor upconversion luminescence was observed with co-doping of Yb2O3 to that of only Er2O3 added α-Sialon ceramics.The upconversion mechanism was governed by two photonic process i.e.excited state absorption(ESA).The energy transfer upconversion(ETU)mechanism was not observed even though Yb2O3 was co-doped.The Er3+ stabilized α-Sialon ceramics shows intense green upconversion at 527 nm and 547 nm wavelengths when excited with 980nm laser.The high visible and IR transmittance were observed for Sialon ceramics up to date.The mechanical properties were also investigated in this study.