aqueous solutions, like the function of stirring. In the presence of glycine, DG n
(DG n ¼ DG surface + DG bulk ) of calcite became relatively higher than that of
vaterite, which would make vaterite to deposit in the first place. The possible reason
is that, in solution, carboxyl group of glycine may affect hydrated surface energies
(de Leeuw & Parker 1997) by interacting with calcium ions like the behavior of
surfactant (Donners et al. 2002a). The solution height may also be an important
factor since the determinant factor in the Gibbs formula is no more surface energy
but bulk lattice energy, which was in accordance with the result of all aragonite
formation. When the height of the solution was lowered, the bulk lattice energy of
aragonite became the lowest.
Glutamic acid and aspartic acid are both acidic amino acid that exist in
biominerals, and their influences on calcium carbonate mineralization have been
studied intensively. It is illustrated that their functions may lay in the negative
electricity of R-radical, which would absorb dissociate Ca
2+ ions or Ca
2+ ions on
crystal surfaces, so as to change the crystallization process of calcium carbonate.
It is found that both glutamic acid and aspartic acid have the ability to induce
vaterite growth in solution. Tong et al. (2004) succeeded in mediating porous
vaterite crystals, considering it was due to the absorption between aspartic acid
and the surface of calcium carbonate crystals, and inhibited formation of calcite.
(Manoli and Dalas 2001) found that glutamic acid could stabilize vaterite crystals.
Fig. 6.15 SEM morphologies of vaterite crystals obtained by the titration and diffusion method.
(a) [Gly] ¼ 10
À3 M, dripping velocity 15 ml/min, C calcite, V vaterite; (b) [Gly] ¼ 10
À3 M,
dripping velocity 2 ml/min; sample without glycine showed similar result; (c) [Gly] ¼ 10
À3 M,
diffusion method, almost all vaterite; and (d) Detailed structure of vaterite, composed of oviods
with a size about 0.1 nm (Hou & Feng 2006b)
174
Q. Feng
(DG n ¼ DG surface + DG bulk ) of calcite became relatively higher than that of
vaterite, which would make vaterite to deposit in the first place. The possible reason
is that, in solution, carboxyl group of glycine may affect hydrated surface energies
(de Leeuw & Parker 1997) by interacting with calcium ions like the behavior of
surfactant (Donners et al. 2002a). The solution height may also be an important
factor since the determinant factor in the Gibbs formula is no more surface energy
but bulk lattice energy, which was in accordance with the result of all aragonite
formation. When the height of the solution was lowered, the bulk lattice energy of
aragonite became the lowest.
Glutamic acid and aspartic acid are both acidic amino acid that exist in
biominerals, and their influences on calcium carbonate mineralization have been
studied intensively. It is illustrated that their functions may lay in the negative
electricity of R-radical, which would absorb dissociate Ca
2+ ions or Ca
2+ ions on
crystal surfaces, so as to change the crystallization process of calcium carbonate.
It is found that both glutamic acid and aspartic acid have the ability to induce
vaterite growth in solution. Tong et al. (2004) succeeded in mediating porous
vaterite crystals, considering it was due to the absorption between aspartic acid
and the surface of calcium carbonate crystals, and inhibited formation of calcite.
(Manoli and Dalas 2001) found that glutamic acid could stabilize vaterite crystals.
Fig. 6.15 SEM morphologies of vaterite crystals obtained by the titration and diffusion method.
(a) [Gly] ¼ 10
À3 M, dripping velocity 15 ml/min, C calcite, V vaterite; (b) [Gly] ¼ 10
À3 M,
dripping velocity 2 ml/min; sample without glycine showed similar result; (c) [Gly] ¼ 10
À3 M,
diffusion method, almost all vaterite; and (d) Detailed structure of vaterite, composed of oviods
with a size about 0.1 nm (Hou & Feng 2006b)
174
Q. Feng