碳酸氢铵与金属阳离子摩尔比对共沉淀法合成铽镓石榴石纳米粉体及陶瓷性能的影响

本研究以碳酸氢铵(AHC)为沉淀剂, 采用共沉淀法制备了TGG粉体。以上述粉体为原料, 将素坯于1500 ℃空气预烧3 h, 然后于1550 ℃, 150 MPa氩气气氛下HIP后处理3 h获得TGG陶瓷。系统研究了碳酸氢铵与金属离子摩尔比(R值)对合成粉体的相组成、形貌以及TGG陶瓷的透光率和Verdet常数的影响。R=3.6, 4.0和4.4的前驱体在1100 ℃煅烧形成纯相TGG粉体, 而R=3.2的前驱体经相同温度煅烧后形成了TGG和Ga₂O₃的混合相粉体。R=4.0的TGG粉体分散性和均匀性最好, 故制备的陶瓷光学质量最佳。R=4.4的粉体具有较严重的团聚, 这与其前驱体形貌密切相关。以R=4.0的粉体为原料, 制备的TGG透明陶瓷在1064 nm处的直线透过率为80.1%。制备的TGG陶瓷在633 nm处的Verdet常数和商业TGG单晶(-134 rad·T ^-1·m ^-1)几乎相等。

Influence of Ammonium Hydrogen Carbonate to Metal Ions Molar Ratio on Co-precipitated Nanopowders for TGG Transparent Ceramics

Terbium gallium garnet (TGG) ceramics were successfully fabricated by air sintering at 1500 ℃ for 3 h combined with HIP post-treating at 1550 ℃ for 3 h under 150 MPa argon gas, where the TGG powders were synthesized by the co-precipitation method employing ammonium hydrogen carbonate (AHC) as precipitant. The influences of ammonium hydrogen carbonate to metal ions molar ratio (R value) on phase composition and morphology of the resultant powders as well as optical transmittance and Verdet constant of the TGG ceramics were investigated systematically. The precursors with R=3.6, 4.0 and 4.4 calcined at 1100 ℃ form pure TGG phase, whereas the precursor with R=3.2 treated at the same temperature yields the mixed phases of TGG and Ga₂O₃. The TGG powder with R=4.0 shows the best dispersity and homogeneity, giving rise to ceramic with the best optical quality. On the contrary, the powder with R=4.4 exhibits a strong agglomeration, which is closely related to the morphology of its precursor. High quality TGG transparent ceramics with the transmittance of 80.1% at 1064 nm can be fabricated by the nanopowder with R=4.0, and the Verdet constant of the TGG ceramics at 633 nm is rather close to that of the commercial TGG single crystals (-134 rad·T ^-1·m ^-1).