Controlled amorphous crystallization: An easy way to make transparent nanoceramics

Fabrication of transparent nanoceramics is attracting more and more interests recently. In this study a new method of amorphous sintering followed by controlled crystallization (ASCC) was developed, and transparent LaAlO3/t-ZrO2 nanoceramic was prepared as an example. Based on a eutectic composition of Al2O3–La2O3–ZrO2, glass powders were synthesized, sintered, and then converted to nanoceramics by post-heat-treatment. The heat-treatment performed at 1200 °C for 2 h produced a transparent LaAlO3/t-ZrO2 nanoceramic with an average grain size of 40 nm. Due to the nanoscale microstructure, the ceramic showed a transparency up to 55% at 800 nm (1 mm thick), Vickers hardness of 19.05 GPa, and fracture toughness of 2.64 MPa m1/2, respectively.

► New method: amorphous sintering followed by controlled crystallization (ASCC).
► Controlled grain growth was achieved by controlled crystallization.
► Transparent LaAlO3/t-ZrO2 nanoceramic with an average grain size of 40 nm.
► Transmittance at 800 nm 55%, Vickers hardness 19.05 GPa, and fracture toughness 2.64 MPa m1/2.