Fabrication of transparent LaAlO3/t-ZrO2 nanoceramics through controlled amorphous crystallization

Transparent nanoceramics are attracting more and more interests recently, while it is practically difficult to prepare by conventional sintering process because of undesirable grain growth. In this study a new method of amorphous sintering followed by controlled crystallization (ASCC) was developed, and transparent LaAlO3/t-ZrO2 nanoceramics were prepared as examples. Glass powders from Al2O3–La2O3–ZrO2 (ALZ) were synthesized, sintered, and then converted to nanoceramics by post-heat-treatment. The processes of hot pressing and controlled crystallization were investigated in detail. 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 composite 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. It is expected to be a promising candidate for window materials.