Sintering and grain growth in SiO2 doped Nd:YAG

Abstract Densification and grain growth in pure YAG, SiO 2 doped YAG and SiO 2 doped Nd:YAG were explored. The activation energy for densification (235 kJ/mol) in pure YAG is lower than that of grain growth (946 kJ/mol) which is unusual in ceramic systems. Consequently, pure YAG sinters to near full density (>99.9%) at 1700 °C with little grain growth (1.2 μm average grain size). The remaining large pores (radius > 2 μm) were determined to be thermodynamically stable because their coordination number with grains was >6. The stability of these pores underscores the importance of powder processing and forming in fabricating transparent YAG. SiO 2 doped YAG sinters to near full density 100 °C lower than pure YAG because SiO 2 enables liquid phase sintering and the removal of large pores. The addition of Nd 2 O 3 further enhances both densification and grain growth at temperatures below 1700 °C. Above 1700 °C higher concentrations of Nd 3+ suppressed grain growth, possibly due to solute drag.