Atomic Displacements in the α-β Phase Transition in Ag2S and in Ag2S/Ag Heterostructure

Orientation relationships between low-temperature monoclinic semiconductor alpha-Ag2S acanthite and high-temperature body-centered beta-Ag2S argentite are determined. It is shown that, in cubic argentite, possible distances between silver atoms are too small for the sites of the metal sublattice to be occupied by Ag atoms with probability equal to one. With regard to the possible arrangement of Ag atoms, it is shown that, during the "acanthite-argentite" transformation, the jump of a silver ion from site (e) of monoclinic acanthite to site (j) of cubic argentite is the most probable process. It is established that the acanthite-argentite transformation in Ag2S/Ag heteronanostructure is accompanied by the formation of a conductive channel of silver Ag and beta-Ag2S argentite under the application of an external voltage. The on-to-off-state current ratio in the synthesized Ag2S/Ag heteronanostructure is approximately equal to 670. For the Ag2S/Ag heteronanostructure, the energy barrier for the hopping of an Ag+ ion from an atomic site of monoclinic acanthite to a site of cubic argentite is estimated.