Two-Step Sintering of Nanocrystalline Tb3Al5O12 Ceramics

Terbium aluminum garnet (Tb 3 Al 5 O 12 , TAG) is a functional ceramic material with potential applications in optical and electronic devices, and its performance is affected by sintering and microstructure. In this work, the sintering behaviors of TAG nanopowders were systematically investigated under various heating schedules. In constant-heating-rate sintering, densification starts at ∼800°C, accelerates at 1000°C–1200°C, and finishes at 1300°C, while grain growth starts at ∼900°C, proceeds slowly below 1100°C, and accelerates rapidly at higher temperatures. Two-step sintering can refine the grain size, yet there is still active grain growth in the second sintering step. Optimized two-step sintering achieves 99.6% relative density while maintaining 93 nm average grain size. Isothermal grain growth experiments have been conducted to quantify the kinetic data of averaged grain boundary mobility at 1100°C–1500°C. The implications for sintering and microstructure control in TAG ceramics shall be discussed.