Electrochemical deposition of silver crystals aboard skylab IV

Abstract

Silver crystals were grown aboard Skylab IV by an electrochemical reaction and subsequently returned to earth for comparison with crystals grown at 1g and 5g. Both the Skylab and earth-grown crystals show a variety of structures. The spacegrown crystals, however, generally possess more perfect microcrystalline forms and are less coherent than earth- or centrifuge-grown crystals. The crystal habits of space and ground electrodeposited silver crystals, furthermore, are very similar to those of germanium selenide (GeSe) and telluride (GeTe) crystals grown in space and on the ground by a vapor transport technique. A likely explanation for the observed crystal habits is that the convective currents prevailing during a deposition play a determining role. In experiments conducted on the ground with solutions of varying concentrations, additional crystal forms were observed. These include downward growing dendrite streamers; upward growing chunky crystal streamers; growth along an air/liquid interface; and ribbon, film, and fiber crystal habits. Convection, again, appears to be an important factor in producing the structures described in the first three preceding cases.