Radiopacity performances of precipitated ZrO₂-doped Bi₂O₃ powders and the influences of dopant concentrations and sintering temperatures

In this study, Bi₂O₃ powders were modified into ZrO₂-doped Bi₂O₃ powders by adding zirconium oxide through precipitation processes. The radiopacity and physical properties of as-synthesized and heat-treated products were investigated. The products were primarily composed of a mixture of β-Bi_7.38Zr_0.62O_12.31 and α-Bi₂O₃ obtained below 700°C, then transferred to β-Bi_7.38Zr_0.62O_12.31 phase above 750°C. With regard to zirconia dopant concentration effects, more zirconium oxide precipitated onto the Bi₂O₃ surface as the x values of Bi_2-xZr_xO_3+x/2 increased from 0.2 to 1.0. As the x value of Bi_2-xZr_xO_3+x/2 powder increased, so too did the surface roughness as a result of zirconia precipitation. In terms of temperature effect, increasing heating temperatures resulted in a smoother powder surface due to liquid phase sintering effect. As for radiopacity analysis, the performances were significantly improved by heat treatments and the effects generally enhanced with increasing temperatures. The overall maximum radiopacity value measured after an 800°C heat treatment was 5.57±0.28mm Al for precipitated ZrO₂-doped Bi₂O₃ powders at x=0.2.