Preparation, structural, Raman and impedance spectroscopic characterisation of the silver ion conductor (AgI)₂Ag₃SbS₃

Abstract

Pale yellow (AgI) 2 Ag 3 SbS 3 was synthesized by the reaction of stoichiometric amounts of AgI and Ag 3 SbS 3 (2 : 1) at 683 K. It is air stable for several months. The crystal structure was determined at different temperatures in the range from 173 K to 573 K by single crystal X-ray diffraction. (AgI) 2 Ag 3 SbS 3 crystallizes in the orthorhombic system, space group Pnnm (no. 58) with a ¼ 10., and Z ¼ 4 (data at 298 K). The title compound is isotypic with (CuI) 2 Cu 3 SbS 3 , at least for the positions of I, Sb, and S. The silver atoms are highly disordered and therefore their displacement parameters were refined using a Gram-Charlier non-harmonic development. No phase transition is observed between 173 K and the melting point at 720 K (DSC, onset temperature). The distribution of silver changes drastically with temperature and the localization of silver increases at low temperature. A high ionic conductivity is observed in combination with a pronounced disorder of the silver atoms. Impedance spectroscopic measurements reveal specific conductivity data of s ¼ 8.

Re-entrant phase transition of the crystalline ion conductor Ag7P3S11

“…This is in good agreement with findings concerning other Cu(I) and Ag(I) compounds [17][18][19]. Only the positions of Ag3 and Ag7 remain fully occupied at room temperature whereas all the other silver positions show some reduced occupancies.…”

“…As documented by various recent examples, ion localization in crystalline silver or copper ion conductors upon cooling can occur under space group conservation [18,19], symmetry reduction [30] or even symmetry increase [31]. In contrast, the silver ion conductor Ag 7 P 3 S 11 reveals a rare case of re-entrant phase behavior: Upon cooling, the hightemperature γ -phase transforms reversibly near 204 K to a polymorph with an unknown space group, but is restored reversibly in a more ordered form at lower temperature (130-135 K).…”

Li17Sb13S28: A New Lithium Ion Conductor and addition to the Phase Diagram Li2S–Sb2S3

“…[22,23] Even mixtures of the ternary compounds with halides, fore xample, (AgI) 2 Ag 3 SbS 3 or (CuI) 2 Cu 3 SbS 3 show pronounced ionicconductivities. [24][25][26][27] Another interestingp oint to note for compounds containing Sb 3 + cations is the steric influence of their 5s 2 lone pair of electrons (E). It has as ignificant structural influence,b ecause of its pronounced steric requirements, and can cause strong structural or physical effects.…”

Li2TeS3 and Li2TeSe3: Preparation, Crystal Structure and Impedance Spectroscopic Characterization

“…Using copper(I) or silver halides as solid solvent revealed a number of solid state compounds with partly good ionic conducting properties [1]. These compounds can be regarded as consisting of a copper(I) or silver halide part on the one hand and of a copper or silver chalcogenometalate on the other hand, see for example [2,3]. We recently started to transfer the findings concerning the mixed halide thiometalate ion conductors of copper and silver to homologous lithium compounds.…”

“…We recently started to transfer the findings concerning the mixed halide thiometalate ion conductors of copper and silver to homologous lithium compounds. A first example for a resulting lithium ion conducting material is (LiI) 2 Li 3 SbS 3 [4] which is closely related to (CuI) 2 Cu 3 SbS 3 [3]. Trying to synthesize (LiI) 3 Li 2 TeS 3 and (LiI) 3 Li 2 TeSe 3 in analogy to (CuI) 3 Cu 2 TeS 3 [14] we always obtained Li 2 TeS 3 and Li 2 TeSe 3 embedded in a LiI flux.…”