Annealing time dependent up-conversion luminescence enhancement in magnesium-tellurite glass

► Er3+-doped silver NPs embedded magnesium-tellurite glasses are prepared. ► TEM confirms the successful precipitation of spherical NPs by heat treatment (HT). ► Luminescence is enhanced due to the growth of NPs after HT up to 24 h. ► With HT>24 h (40 h) there is quenching in luminescence intensity. ► Enhancement is attributed to the local field effect of silver NPs.