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

In order to produce alpha-calcium sulfate hemihydrate (alpha-CaSO4 center dot 0.5H(2)O) whiskers with high aspect ratios, a minor amount of CuCl2 center dot 2H(2)O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate (CaSO4 center dot 2H(2)O) precursor. The presence of 2.60x10(-3) mol/L CuCl2 center dot 2H(2)O resulted in the increase of the aspect ratios of alpha-CaSO4 center dot 0.5H(2)O whiskers from 81 to 253. The preferential adsorption of Cu2+ on the negative {110} and {100} facets of alpha-CaSO4 center dot 0.5H(2)O crystal structures was confirmed by EDS and XPS. And ATR-FTIR demonstrated the ligand adsorption of Cu2+ on the surface of alpha-CaSO4 center dot 0.5H(2)O 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 alpha-CaSO4 center dot 0.5H(2)O whiskers along the c axis.