Effects of lattice defective spinel addition on broad-band light absorption, electrical and mechanical properties of alumina composite ceramics

With the rapid development of the semiconductor integrated circuits, higher optical, electrical, and mechanical properties of vacuum chucks are required to prevent the influence of light reflection, avoid the breakdown of component from electrostatic accumulation and ensure wear resistance to extend its service life. In this paper, MnO 2 is introduced to Al 2 O 3 -Cr 2 O 3 -TiO 2 composite to form lattice defective spinel to regulate the optical, electrical, and mechanical properties of alumina ceramics via vacuum sintering. The X-Ray diffraction (XRD) results reveal that the phase of composites are Al 2 O 3 and spinel, with a noticeable leftward shift trend of spinel's diffraction peaks corresponding to larger lattice constants. The X-ray photoelectron spectroscopy (XPS) analysis confirms the increase of Mn 3+ , Mn 2+ , and Vö, where Mn 3+ replaces Al 3+ in the spinel, resulting in an increase in the lattice constant. Additionally, the aliovalent ionic substitution formed oxygen vacancy (Vö) introduces defect energy levels and decreases band-gap energy (from 1.332 to 1.248 eV), which significantly enhances the light absorption performance of black alumina ceramics in the UV–VIS–NIR range. Moreover, the Vö acts as the path of free electrons in the material, thereby reducing its volume resistivity to 7.06 × 10 11  Ω cm. Although the existence of defects leads to stress concentration, the mechanical property of black ceramics remain satisfactory due to the smaller grains. As the MnO 2 content is 1.5 wt%, the absorptivity is greater than 85 % in the UV–VIS–NIR range (91.7 %@564 nm), and the volume resistivity, hardness, fracture toughness are 6.53 × 10 12  Ω cm, 13.12 GPa, 2.36 MPa m 1/2 respectively, which provides a candidate material for vacuum chuck applying in semiconductor manufacturing.