Preparation and properties of novel (Tb1-xCex)(3)Sc2Al3O12 magneto-optical transparent ceramics with different doping concentrations

The current development direction of magneto-optical (MO) isolators involving miniaturisation and application in high-power lasers encounters difficulties in material application because preparing materials with excellent optical quality and a high Verdet constant remains a challenge. Herein, (Tb1-xCex)(3)Sc2Al3O12 (x = 0.001, 0.0025, 0.005, 0.01, 0.015, 0.02) MO ceramics with different doping concentrations were prepared by vacuum sintering. The phase structure, element distribution, microstructure, relative density, optical properties, surface properties and MO properties of the (Tb1-xCex)(3)Sc2Al3O12 ceramics were also characterised. Experimental characterisation reveals that the (Tb1-xCex)(3)Sc2Al3O12 ceramics have a pure Tb3Sc2Al3O12 (TSAG) phase and exhibit an excellent uniform element distribution. In addition, no secondary phase was detected in FESEM images with the increase in Ce concentration. However, a few small-sized residual pores, which remain entrapped in the Ce(0.015)TSAG and Ce(0.02)TSAG ceramics, can be observed. Moreover, all the obtained ceramics have good optical quality, and the in-line transmittances of the (Tb1-xCex)(3)Sc2Al3O12 ceramics at 1064 nm are 81.7%, 83.7%, 80.0%, 84.0%, 68.8% and 77.7%. The Verdet constant of the ceramics is optimised by Ce doping, and the Verdet constants of all the ceramics at the test wavelength are better than those of TSAG ceramic. The Verdet constant of the Ce(0.01)TSAG ceramic is still superior to that of the TSAG ceramic in the same temperature range. Finally, the extinction ratio values for the Ce(x)TSAG (x = 0.001, 0.0025, 0.005, 0.01) ceramics exceeded 40 dB. The Ce(0.01)TSAG ceramic shows the best optical transmittance, the highest magneto-optical FoM values and the highest Verdet constants. Thus, this ceramic can be used for a high-power laser in the visible and near-infrared regions in the future.