Structure—Property Relations and Diffusion Pathways of the Silver Ion Conductor Ag₅Te₂Cl.

Abstract

Single-crystal structure determinations at room temperature and elevated temperatures were carried out on the silver ion conductor Ag 5 Te 2 Cl, and the hitherto unknown structure of the room-temperature phase ( -Ag 5 Te 2 Cl) was determined. Ion pathways are discussed for the room-and high-temperature phase by analyzing the joint probability density functions. Main transport pathways at different temperatures were worked out to obtain detailed insight into the movement of the silver atoms in this material. Ag 5 Te 2 Cl is an excellent 1D ionic conductor having a pronounced silver mobility along complex silver columns. Conductivities are σ ) 1.51 × 10 -3 Ω -1 cm -1 at 323 K and σ ) 4.30 × 10 -1 Ω -1 cm -1 at 469 K. With use of a nonharmonic description of the silver distribution of the high-temperature phase, a promising structure model has been derived for the room-temperature phase.-Ag 5 Te 2 Cl can be regarded as an intermediate phase between the disordered high-and the ordered low-temperature phase, showing an almost ordered silver distribution in addition to a slightly different arrangement of the anionic substructure.

Structure−Property Relations and Diffusion Pathways of the Silver Ion Conductor Ag5Te2Cl

“…In contrast to the thermodynamically nonstable phases MAg 4 I 5 (M = Rb, K, NH 4 ) , at room-temperature Ag 5 Te 2 Cl shows no decomposition in the presence of moisture or light over months. Silver NMR spectroscopic investigations performed in the stability area of γ -Ag 5 Te 2 Cl show an activation energy of 0.42 eV, which is supposed to be the same as that for β -Ag 5 Te 2 Cl within the experimental error. This finding corresponds to the data reported earlier where no difference in the activation energies of the β - and γ -phase could be observed …”

Synthesis, crystal and electronic structure, and optical properties of two new chalcogenide-iodides: Ba3Q4I2 (Q = S, Se)

“…The recent discoveries of giant Rashba-type splitting in BiTeI, 1,2 spin density waves in La 2 TeI 2 , 3 high ionic conductivity and excellent thermoelectric properties in Ag-Te-X compounds (X = Cl, Br) are just few examples of the diversity in metal chalcogenide-halides. [4][5][6][7][8] In contrast to the ternary rare-earth-or transition metal-chalcogenide-halides, no ternary alkaline-earth-containing sulfide-or selenide-halides have been reported. [9][10][11] Only a few quaternary or higher order compounds have been reported in literature, such as Ba 4 Fe 2 S 4 I 5 , 12 Ca 2 LaGeS 4 Cl 3 , 13 and ABa 3 Ga 5 Se 10 Cl 2 (A = Cs, Rb, K).…”