Copper intercalation into Bi2Te3 single crystals

The process of electrochemical intercalation and deintercalation of copper ions into Bi2Te3 single crystals was studied and a conception of embedding of copper ions into octahedral and tetrahedral sites of the van der Waals gaps was proposed. Taking the lattice–gas model into consideration, values of octahedral and tetrahedral site energies, E1=−0.07 eV and E2=−0.31 eV, were determined. It was found that intercalated copper ions behave either as donors located in the van der Waals gaps and interstitial sites of five-plane layers of the crystal or as inactive species. To enlighten this effect, a model assuming an interaction of Cu+ ions with Te1 atomic planes and the formation of uncharged four-layer lamellae (Cu–Te–Bi–Te) and seven-layer lamellae carrying delocalised negative charge (Bi3Te4)− was proposed.