TY - JOUR
T1 - Theory of electrolyte crystallization in magnetic field
AU - Madsen, Hans Erik Lundager
PY - 2007
Y1 - 2007
N2 - Crystallization from aqueous solution of a sparingly soluble electrolyte is accelerated by magnetic field if the crystalizing phase is a diamagnetic salt of a weak acid, and crystallization is from neutral or acid solution in ordinary (not heavy) water. Since the effect of Lorentz force is negligible, if not absent, the key property is likely to be the spin of protons which, by virtue of their half-integral spin, are fermions. An effect on crystal growth kinetics has been demonstrated, and the apparent effect on nucleation concerns the growth rate of nuclei. We are thus dealing with surface phenomena. The basis of the theory is a crystal model of a sparingly soluble salt with NaCl structure, where the ions are divalent, and the anion is a base. It is assumed that almost all the anions in the surface layer are protonized, and that an approaching metal ion pushes the proton away to a neighbouring anion, which then becomes doubly protonized. If the two protons are in the same spin state, the Pauli principle requires that one of them enter a state of higher energy, which enhances the activation energy and reduces the rate of the process, but even with opposite spins the incoming proton must enter an excited state due to its momentum. Spin relaxation in magnetic field may remove hindrances to proton transfer. The theory is supported by numerical results from model calculations.
AB - Crystallization from aqueous solution of a sparingly soluble electrolyte is accelerated by magnetic field if the crystalizing phase is a diamagnetic salt of a weak acid, and crystallization is from neutral or acid solution in ordinary (not heavy) water. Since the effect of Lorentz force is negligible, if not absent, the key property is likely to be the spin of protons which, by virtue of their half-integral spin, are fermions. An effect on crystal growth kinetics has been demonstrated, and the apparent effect on nucleation concerns the growth rate of nuclei. We are thus dealing with surface phenomena. The basis of the theory is a crystal model of a sparingly soluble salt with NaCl structure, where the ions are divalent, and the anion is a base. It is assumed that almost all the anions in the surface layer are protonized, and that an approaching metal ion pushes the proton away to a neighbouring anion, which then becomes doubly protonized. If the two protons are in the same spin state, the Pauli principle requires that one of them enter a state of higher energy, which enhances the activation energy and reduces the rate of the process, but even with opposite spins the incoming proton must enter an excited state due to its momentum. Spin relaxation in magnetic field may remove hindrances to proton transfer. The theory is supported by numerical results from model calculations.
KW - Former LIFE faculty
KW - Magnetic fields
KW - Proton transfer
KW - Surface processes
KW - Salts
U2 - 10.1016/j.jcrysgro.2007.04.023
DO - 10.1016/j.jcrysgro.2007.04.023
M3 - Journal article
SN - 0022-0248
VL - 305
SP - 271
EP - 277
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 1
ER -