Thermodynamic properties of solid solutions of superionic copper, silver, and lithium chalcogenides

Cu2Se and Cu Nanocrystals as Local Sources of Copper in Thermally Activated In Situ Cation Exchange

“…Bekenstein et al recently showed that the thermal annealing of a film of copper sulfide NCs increased the number of Cu vacancies in the NCs, resulting in a modification of their electronic properties . Similarly, different groups investigated the variation in the optical behavior of copper chalcogenide NCs when subject to postsynthetic processes which modify the Cu stoichiometry, demonstrating a direct correlation between Cu deficiency ( x ) in the NC lattice and the emergence of a localized surface plasmon resonance (LSPR). − Copper chalcogenides have the additional peculiarity of undergoing a phase transition above a thermal threshold to a superionic (SI) phase, with highly mobile copper ions in the lattice. − In particular, copper selenide (Cu 2 Se) transforms at high temperature into a Cu-depleted superionic Cu 2– x Se phase, characterized by a liquid-like behavior of the Cu cations within a rigid Se sublattice having face-centered cubic (fcc) structure. − Here, we aimed to assess whether Cu 2 Se NCs do lose a measurable fraction of Cu atoms from their lattice once deposited on a substrate and annealed above a certain threshold temperature. If so, our next goal was to clarify if the expelled Cu species could engage in “dry” CE reactions, involving NCs of another ionic material deposited on the same substrate, in our case either CdSe nanorods (NRs) or CdSe nanowires (NWs).…”

Determining conductivity and mobility values of individual components in multiphase composite Cu1.97Ag0.03Se

“…This is supported by X-ray diffraction by Brown et al 12 in which the reflections of Cu 1.97 Ag 0.03 Se are shifted to smaller values of 2H, indicating a larger lattice, which is consistent with the larger Ag cations located on vacant Cu sites. 26 Ordinarily these vacant sites create holes in Cu 2 Se; an Ag atom on such a site donates an electron and reduces the number of positive charge carriers. Ag has been shown to reduce the carrier concentration in Cu 2 Se, 13 further supporting the idea that the matrix is Ag-doped Cu 2 Se.…”

Influence of the cation sublattice defectness on the electronic thermoelectric power of Li x Cu(2−x)−δ (x ≤ 0.25)

“…Particular attention should be paid to the very large Peltier and Seebeck coefficients at low lithium contents (the alloys and ), which is of great interest for application in thermo electric devices. From experimentally determined enthalpies of as functions of the devia tion from stoichiometry, δ, Balapanov et al [11] inferred a high degree of cation disorder in this mate rial. Data on the electronic structure and carrier effec tive mass of are still missing.…”