Fig. 1 Sintering trajectories of MAGS-0.1 ceramics with 0.1%, 0.2% and 0.5% MgF2 and the unaided MAGS-0.1 ceramics Colorful figure is available on website

Fig. 2 Variations of the shrinkage and shrinkage rate of MAGS-0.1 ceramic green bodies containing 0 and 0.2% MgF2 as a function of temperature (a) Shrinkage curves; (b) Shrinkage rate curves

Fig. 3 TG-DSC curves of MAGS-0.1 powder containing 10% MgF2 and XRD patterns of MAGS-0.1 powder containing 10% MgF2 after heating and holding at different temperatures (a) TG-DSC curves of MAGS-0.1 powder containing 10% MgF2 heated at 10 ℃/min; (b) XRD patterns of MAGS-0.1 powder containing 10% MgF2 after heating and holding at 1150, 1250, 1350 and 1450 ℃ for 5 min followed by quenching; (c) Enlarged XRD patterns of the (220) crystal face in (b)

Fig. 4 Presintering mechanism of MAGS-0.1 ceramics with MgF2

Fig. 5 Phase compositions of powder, pre-sintered and transparent ceramic samples

Fig. 6 Surface SEM images and grain size distributions of MAGS-0.1 ceramics with different additive contents after pressureless presintering and chemical etching (a, d) Sample with 0.2% MgF2; (b, e) Sample with 0.5% MgF2; (c, f) Sample without additive

Fig. 7 Surface SEM images and grain size distributions of MAGS-0.1 ceramics after HIP sintering and chemical etching (a, c) Sample with 0.2% MgF2; (b, d) Sample without additive

Fig. 8 Appearance images of MAGS-0.1 transparent ceramics without additive and with 0.2% MgF2 (a) Sample with 0.2% MgF2; (b) Sample without additive

Fig. 9 Optical polarized transmission micrographs of transparent ceramics without additive and with 0.2% MgF2 (a) Sample with 0.2% MgF2; (b) Sample without additive

Fig. 10 Optical properties of samples with different additive contents and sizes Inset: Appearance image of a sample containing 0.2% MgF2 with ϕ108.8 mm×9.36 mm

Fig. 11 Weibull plots of fracture strength for MAGS-0.1 transparent ceramics (a) Sample without additive[6]; (b) Sample with 0.2% MgF2