Optimizing optical and mechanical properties of hundred-micron transparent ceramic fibers through controlled ball milling time for gelcasting

Transparent ceramic fiber is the appealing material for fiber laser gain media. Currently, the presence of micro-pore defects and poor optical quality in hundred-micron ceramic fibers greatly limits their application in fiber lasers. In this paper, high optical quality YAG (Y3Al5O12) ceramic fibers were prepared by optimizing the ball milling time of slurry, and revealed that dispersion behavior of slurry was crucial to prepare good microstructure and defect-free green body and ceramic fibers. The excellent optical and mechanical properties of transparent ceramic fibers were obtained with the ball milling time of 25 h for slurry and sintering at 1780 °C for 8 h for ceramics. The transmittance of YAG ceramics (2 mm thick) at 800 nm of 82.6 % and a high flexural strength of 1124 ± 86 MPa could be observed. However, the longer ball milling time would thicken the slurry and deteriorate the uniformity slurry. This optimized processing technology of gelcasting could promote the quality of hundred-micron sized ceramics fibers.