Measurements of the thermopower and of the thermal diffusivity and a detailed analysis of the structural features by temperature-dependent single-crystal structure determinations of silver ionconducting Ag5Te1.8Se0.2Cl and Ag5Te1.6Se0.4Cl were performed to investigate the interaction of silver ions in their disordered state. The substituted phases show an order/disorder phase transition at 273.3(2) and 302.5(2) K, respectively, accompanied by a drop of the thermal diffusivity and a minimum plateau of the thermopower right after the transition. Silver ions are arranged in welldefined strands along the crystallographic c axis characterized by a set of not fully occupied sites. Ag5Te1.6Se0.4Cl shows a negative thermal expansion during temperature rise right after the silver order/disorder phase transition; this is explicable by attractive d10-d10 interactions within the disordered silver substructure. After the minimum values of the thermopower have been reached, these values rise in parallel to the decrease of the d10-d10 interactions. Ag5Te1.6Se0.4Cl shows a very low value of the thermal diffusivity of 0.070 mm2 s−1 at 300.7 K.
Graphical Abstract
The Influence of d10-d10 Interactions in Ag5Te1.8Se0.2Cl and Ag5Te1.6Se0.4Cl on Structural and Thermoelectric Properties
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