Fabrication of transparent LaAlO 3/t-ZrO 2 nanoceramics through controlled amorphous crystallization

Abstract

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 LaAlO 3/t-ZrO 2 nanoceramics were prepared as examples. Glass powders from Al 2O 3–La 2O 3–ZrO 2 (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 LaAlO 3/t-ZrO 2 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 m 1/2, respectively. It is expected to be a promising candidate for window materials.