Fabrication of high optical quality TAG ceramics by vacuum sintering and non-stoichiometric Mg2+-Si4+ co-doping

To minimize the residual scattering of sintering aids, reducing their addition amount is one of the long-standing guidelines in preparing high optical quality transparent ceramics, e.g. Tb3Al5O12(TAG) magneto-optic (MO) ceramics. However, what has been overlooked in previous studies is that traditional sintering aids are generally added in a weight ratio that would inevitably result in residues in the matrix. To address this issue, we use Mg2+ and Si4+ ions as the constituents of the TAG lattice for non-stoichiometric ratio co-doping in this work. Without a reduction in the absolute amount of MgO and TEOS, high optical quality TAG ceramics were obtained by only one-step vacuum solid-state sintering. The sample with a nominal formula of Tb-2.97(Mg0.005Al0.995-xSix)(5)O11.9425+5x/2 (x=0.005) showed a transmittance of 82.48% and optical loss of 0.048 cm(-1) at 1064 nm, which has the highest transmittance and lowest optical loss of any reported value obtained by similar sintering method, to the best of our knowledge. The influence of Si doping content on the microstructure and optical properties of TAG ceramics has been systematically analyzed. The non-stoichiometric lattice doping instead of traditional sintering aids may provide an effective solving thought for preparing other high-quality ceramics affected by residual sintering additives for high power laser systems.