Direct Quantification of Ordering at a Solid-Liquid Interface Using Aberration Corrected Transmission Electron Microscopy

We have used aberration corrected in situ transmission electron microscopy to study the interface between liquid Al and different sapphire facet planes, including quantitative analysis of the degree of residual contrast delocalization, ensuring that the experimental contrast perturbations can be associated with density perturbations in the liquid. The results confirm that the liquid is ordered at the interface, and the degree of ordering varies as a function of the sapphire facet planes, with a decreasing degree of order according to $\{0006\}>\{1\overline{2}10\}>\{10\overline{1}2\}\ge \{\overline{1}014\}$.

Figure 1

$C_s$ corrected ($C_s=-2.4\mu \mathrm{m}$) HRTEM micrograph of a liquid Al droplet located at the ($1\overline{2}10$) surface of solid ${\mathrm{Al}}_2{\mathrm{O}}_3$. The micrograph was acquired at $T=750°\mathrm{C}$. The sapphire crystal is oriented in a [$10\overline{1}0$] zone axis. The inset is the intensity line scan perpendicular to the $\mathrm{Al}\mathrm{\text{−}}{\mathrm{Al}}_2{\mathrm{O}}_3$ interface from the region marked on the micrograph by a black rectangle. The dashed curve on the graph represents the exponential fit, from which $\xi$ was extracted.

Figure 2

(a) $C_s$-corrected ($C_s=-5.2\mu \mathrm{m}$) HRTEM micrograph of sapphire partially in contact with liquid Al. The micrograph was acquired at $T=750°\mathrm{C}$. The sapphire is oriented in a [$1\overline{2}10$] zone axis. (b) Intensity line scan perpendicular to the interface between liquid Al and the ($\overline{1}014$) sapphire surface. (c) Intensity line scan perpendicular to the interface between liquid Al and the (0006) sapphire surface. The dashed curves on (b) and (c) represent the exponential fit, for which $\xi$ was extracted.

Figure 3

(a) $C_s$-corrected ($C_s=-6.6\mu \mathrm{m}$) HRTEM micrograph of liquid Al partially confined by sapphire. The micrograph was acquired at $T=670°\mathrm{C}$. The sapphire is oriented in a [$\overline{1}2\overline{1}0$] zone axis. (b) Intensity line scan perpendicular to the interface of liquid Al with ($10\overline{1}2$) sapphire. (c) Intensity line scan perpendicular to interface of liquid Al with (0006) sapphire. The dashed curves in (b) and (c) represent the exponential fit, from which $\xi$ was extracted.