Doping effect of Al on the yellow chromogenicity of V-doped ZrO<sub>2</sub>

In this study, the effect of Al addition on the yellowness of V-doped ZrO2 was investigated. V-, Al-, and (V,Al)-doped as well as pure ZrO2 powders were prepared via complex polymerization, and their thermally decomposed products were characterized. The absorption edge of the V-doped ZrO2 exhibited a red shift as the heating temperature increased. In addition, the intensity of the absorption peaks centered at approximately 350 nm increased when Al was added to V-doped ZrO2. The yellowness parameter b* increased significantly when V was added to ZrO2; however, the addition of Al to ZrO2 did not improve b*. When Al was added to V-doped ZrO2, the b* value was significantly higher than that when only V was added, particularly after calcination at 700 °C. Furthermore, it was found that V in V- and (V,Al)-doped ZrO2 was primarily present as V5+ and partially V4+ using X-ray photoelectron spectroscopy.