Preparation of α-calcium sulfate hemihydrate whiskers with high aspect ratios in presence of a minor amount of CuCl₂·2H₂O

Abstract

In order to produce α-calcium sulfate hemihydrate (α-CaSO₄·0.5H₂O) whiskers with high aspect ratios, a minor amount of CuCl₂·2H₂O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate (CaSO₄·2H₂O) precursor. The presence of 2.60×10^-3 mol/L CuCl₂·2H₂O resulted in the increase of the aspect ratios of α-CaSO₄·0.5H₂O whiskers from 81 to 253. The preferential adsorption of Cu²⁺ on the negative {110} and {100} facets of α-CaSO₄·0.5H₂O crystal structures was confirmed by EDS and XPS. And ATR-FTIR demonstrated the ligand adsorption of Cu²⁺ on the surface of α-CaSO₄·0.5H₂O whiskers. The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu²⁺, which promotes the 1-D growth of α-CaSO₄·0.5H₂O whiskers along the c axis.

Keywords

α-CaSO₄·0.5H₂O whisker / CuCl₂·2H₂O / hydrothermal treatment / aspect ratio

References

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