Silver(I)-(poly)chalcogenide Halides – Ion and Electron High Potentials

Abstract

Materials with high dynamics in the solid state are of potential interest in semiconductor science and for a great variety of energy applications. In most of the cases the majority of physical properties of such compounds are directly related to their electronic structure. Optimization of properties is therefore correlated with direct or indirect control of this parameter. Compounds with highly mobile ions like the coinage metal cations and the heavy chalcogenide anions can easily be modified chemically or physically to fine tune their electronic structures. The range of adjustable properties lasts from ion conductivity, magneto resistance, thermoelectricity to a reversible redox-driven switch of semiconductivity. Today, the strong demand on clean energy production, the efficient energy transport and energy storage is a major goal for present and oncoming generations. Stable, mixed-conducting materials will play a major role in this process. The ongoing development of coinage metal chalcogenide halides during the last 50 years reflects the fundamental interest in this field. Many interesting and sometimes unexpected properties have been determined recently which substantiates the great potential of this class of materials. Especially the new class of coinage metal polychalcogenide halides is of potential interest due to their drastic modulations of physical properties driven by a fundamental tuning of its electronic structures. Thermopower and thermal diffusivity, two major properties to tune thermoelectricity can be varied in such a way that drastic changes can be addressed in very small temperature ranges close to room temperature. Herein we report on the recent progress of polychalcogenide and chalcogenide halides with the mobile d 10 ions Ag and Cu putting the main focus on silver compounds.

The Influence of d10-d10 Interactions in Ag5Te1.8Se0.2Cl and Ag5Te1.6Se0.4Cl on Structural and Thermoelectric Properties

“…A modulation of the electronic structure can be achieved based on these low-dimensional interactions which do significantly influence the thermopower and the thermal diffusivity of these materials [12,18]. A strong influence on the electronic structure and the thermopower originating from a Peierls-distorted situation has also been postulated for lead chalcogenides (PbQ with Q = S, Se, Te) under high-pressure conditions [19].…”

Ion Dynamics and Polymorphism in Cu20Te11Cl3

“…Besides their application in data storage as phase-change materials and resistivity switching memories, − they play a certain role in solar cells and thermoelectrics, where improvement of the efficiency is still a challenging task . Ternary coinage metal (poly)­chalcogenide halides are a class of mixed conductors with high potential for application as thermoelectric energy conversion materials. , They show high cation mobility and, because of their ternary character, offer the possibility for multiple ion substitution. Fine tuning of the electronic structure, which is an important parameter for optimization of the thermoelectric and electronic properties, is possible .…”

“…Ternary coinage metal (poly)­chalcogenide halides are a class of mixed conductors with high potential for application as thermoelectric energy conversion materials. , They show high cation mobility and, because of their ternary character, offer the possibility for multiple ion substitution. Fine tuning of the electronic structure, which is an important parameter for optimization of the thermoelectric and electronic properties, is possible . The named class of compounds summarizes the completely ionic silver­(I) chalcogenide halides on the quasi binary section Ag 2 Q–AgX with Q = S, Se, and Te and X = Cl, Br, and I and the coinage metal polychalcogenide halides that contain both isolated chalcogenide anions and predominantly covalently bonded polyanionic chalcogene units.…”

“…5 Ternary coinage metal (poly)chalcogenide halides are a class of mixed conductors with high potential for application as thermoelectric energy conversion materials. 6,7 They show high cation mobility and, because of their ternary character, offer the possibility for multiple ion substitution. Fine tuning of the electronic structure, which is an important parameter for optimization of the thermoelectric and electronic properties, is possible.…”

“…Fine tuning of the electronic structure, which is an important parameter for optimization of the thermoelectric and electronic properties, is possible. 7 The named class of compounds summarizes the completely ionic silver(I) chalcogenide halides on the quasi binary section Ag 2 Q−AgX with Q = S, Se, and Te and X = Cl, Br, and I and the coinage metal polychalcogenide halides that contain both isolated chalcogenide anions and predominantly covalently bonded polyanionic chalcogene units. Representatives of the first group are Ag 5 Te 2 X with X = Cl and Br 8−13 and Ag 19 Q 6 X 7 with Q = S, Se, and Te and X = Br and I.…”