ON THE EFFECTS OF LiF ON THE SYNTHESIS AND REACTIVE SINTERING OF GAHNITE (ZnAl2O4)

Zinc Aluminate Spinel, ZnAl₂O₄, which is also designated as gahnite, is a ceramic semiconductor with a band gap of about 3.9 eV and large absorbance in the UV region, thus it has emerged as an alternative choice for transparent conducting oxide when doped with transition metal ions. The effects of LiF on the synthesis and reactive sintering of polycrystalline gahnite (zinc aluminate spinel, ZnAl₂O₄) were studied using XRD, high-temperature simultaneous thermal analysis and a spark plasma sintering (SPS) apparatus. It was demonstrated that the LiF reduces the onset of synthesis by about 200°C and plays an important role in the densification process. SPS consolidation of a LiF-doped ZnO-Al₂O₃ mixture under an applied pressure of 150 MPa and at a sintering temperature of 1100ºC for 20 min generated fully dense gahnite with adequate transparency and mechanical properties.