Fig. 9
From: Room-temperature superionic-phase nanocrystals synthesized with a twinned lattice
Characteristics of Cu2−xS NCs of a smaller size. a Representative TEM image (scale bar = 10 nm) of Cu2−xS NCs of a smaller diameter prepared with no air-injection and b histogram showing the NC diameter distribution determined by ImageJ analysis of the TEM image. The average diameter of the NCs is determined to be 3.3 nm with a standard deviation of 0.3 nm. c Vis–NIR extinction spectrum (normalized to 1 at 2 eV) of the Cu2−xS NCs of 3.3 nm average diameter. The NCs synthesized with no air-injection are expected to have a stoichiometry of Cu1.97S analogous to the case of ca. 7 nm diameter NCs, however the LSPR absorption of these smaller NCs was too weak to assign an ωsp. It is possible the NCs are nearly Cu2S in stoichiometry. d DSC thermograms of the these NCs. Thermograms from two heating–cooling cycles performed on the same sample of NCs are shown, from which the reproducibility of the phase-transition peaks (dips) is evident. The peak temperature of the phase-transition in the heating sub-cycle was averaged over the two cycles to yield a Tc of 24 °C with a standard deviation of 0.3 °C
