The influence of an interface electric field on the distribution coefficient of chromium in LiNbO₃

The effective solute partitioning of chromium was investigated on single crystals of LiNbO₃ grown by the laser-heated pedestal growth (LHPG) technique. Electric field effects at the interface influence this solute partitioning, leading to an electric field-dependent effective solute distribution coefficient, k_E. The LHPG technique made it possible to explore these field effects by controllably changing the growth velocity (V) and the temperature gradient (G_S, G_L) near the interface over a wide range. The electric field generated via the temperature gradient is associated with the thermoelectric power while an additional electric field is growth rate associated via a charge separation effect. By applying the Burton-Prim-Slichter (BPS) theory to our experimental data, we found the phase diagram solute partition coefficient to be k₀ ≈ 3.65, while the field-influenced solute partition coefficient (V = 0) was k′_EO ≈ 8.17 at G_L ≈ 11500°C/cm. It is theoretically shown that the same considerations can be applied to all ionic partitioning at a solid-liquid interface.