Effect of Mg2+ on hydrothermal formation of α-CaSO4·0.5H2O whiskers with high aspect ratios.

The effect of Mg(2+) on hydrothermal formation of α-CaSO4·0.5H2O whiskers with high aspect ratios was investigated in this paper. α-CaSO4·0.5H2O whiskers with a preferential growth along the c axis and an average aspect ratio up to 370 were synthesized using hydrothermal treatment of CaSO4·2H2O precursor in the presence of 1.97 × 10(-3) mol·L(-1) MgCl2. The preferential adsorption of Mg(2+) on the negative (200), (400), and (020) facets was confirmed by EDS, XPS, and zeta potential measurements. ATR-FTIR analysis revealed the ligand adsorption of Mg(2+) on the surface of α-CaSO4·0.5H2O. The doping of Mg(2+) in α-CaSO4·0.5H2O whiskers was confirmed by the XRD analysis. The experimental results indicated that the adsorption and doping of Mg(2+) promoted the 1-D growth of α-CaSO4·0.5H2O whiskers, leading to the formation of whiskers with high aspect ratios.