Lattice spacings of very thin gold platelets

Abstract

Using precision selected‐area electron diffraction methods, the lattice spacings in the plane of the platelets has been determined for chemically grown gold platelets ranging in thickness from 80 to 400 Å. These parameters have been determined to ±0.03%. It has been found that in all cases the spacings are less than that of bulk gold. The discrepancy varied from 0.28 to 0.04% and was larger for thinner crystals. If the effect is due to surface stress then one would expect a straight‐line plot of lattice parameter vs reciprocal thickness. In fact the results for the seven thicker platelets lie on the good straight line with an axial intercept within 0.01% of the value for bulk gold. The two thinner platelets have a greater parameter decrease than expected. From the straight‐line plot the value for the surface stress of Au at room temperature was determined to be 1070±75 dyn/cm.