采用真空固相反应烧结技术制备了YAG 透明陶瓷，测试了陶瓷素坯的热膨胀曲线、陶瓷样品的透过光谱及表面微结构。深入研究了MgO 作为烧结助剂，其添加量对YAG 透明陶瓷显微结构、光学透过率等性能的影响。结果表明，在1780 ℃下保温6 h，制备得到具有高透明度的YAG 透明陶瓷。0.1%以上（质量分数，下同）的MgO 添加量有利于陶瓷的致密化，但由于第二相的产生及气孔不能排除，严重降低了陶瓷的光学质量；添加0.03%的MgO 最有利于透明陶瓷的烧结，制备得到的陶瓷晶粒尺寸均一，几乎无晶内及晶间气孔，其在波长1200 nm 处的透过率约为82 %。

YAG transparent ceramic has been fabricated by the vacuum sintering technique with MgO as sintering aids. Thermal expansion curves of the green samples, optical transmittance spectrum, and surface microstructure of the prepared YAG ceramics were measured. The effect of MgO content on the microstructure and in-line transmittance of the samples was studied. Results show that transparent ceramics with high optical quality are obtained after vacuum sintering at 1780 degrees C for 6 h. Ceramics with MgO at the level above 0.1 wt% are easy to densify; however, the second phase and pores appear then, which do harm for the optical quality of the samples. 0.03 wt% of MgO content benefits the sintering process most. Uniform grains are gained, with neither inner nor intergranular pores. The in-line transmittance of the ceramic at 1200 nm reaches 82%.