Variation of physical properties of silver(I) chalcogenide halides by modification of the anion substructure Stefan Lange Institute of Inorganic Chemistry University of Regensburg NRW Graduate School of Chemistry, 25.–

Ag 5 Te 2 Cl is a trimorphic compound:  -Ag 5 Te 2 Cl  -Ag 5 Te 2 Cl  -Ag 5 Te 2 Cl monoclinic (P 2 1 /c) monoclinic (P 2 1 /n) tetragonal (I 4/mcm) a=1935.9(1) pma=1385.2(3) pma=974.9(2) pm b=771.3(1) pmb=766.3(2) pm c=1953.3(1) pmc=1366.1(3) pmc=783.6(2) pm Z=16Z=8Z=4  =90.6(1)°  =90.09(1)° (193 K)(298 K, powder XRD) (363 K, powder XRD) R. Blachnik, H. A. Dreisbach, J. Solid State Chem., (1985), 60, 115. Th. Doert, E. Rönsch, F. Schnieders, P. Böttcher, Z. Anorg. Allg. Chem., (2000), 626, T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, Ag 5 Te 2 Cl: Structures 334 K 241 K

T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, Anion substructure: minor distortion of the anion sublattice upon phase transition  -  -  description as alternating nets in projection along selected crystallographic axes: 4 4 for Cl and for Te Ag 5 Te 2 Cl: Structures 

Anion substructure: Ag 5 Te 2 Cl: Structures T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, minor distortion of the anion sublattice upon phase transition  -  -  description as alternating nets in projection along selected crystallographic axes: 4 4 for Cl and for Te 

Anion substructure:  Ag 5 Te 2 Cl: Structures

Cation substructure:   - phase (HT): quasi-molten sublattice of silver 1-dim. infinite Ag-cords along c partly occupied silver sites high isotropic and anisotropic displacement parameters   - phase (RT): partial localization of Ag all Ag sites fully occupied still rather high displacement parameters for some positions   - phase (LT): closely related to the  -(RT)-modification, further localization of silver Ag 5 Te 2 Cl: Structures

Ag 5 Q 2 X: Ag-coordination 4 different types of silver coordination in the  -phase: Aga{1,2,3,4,5,8}: distorted tetrahedral coordination by 3 Te + 1 Cl Aga{6,7}: distorted tetrahedral coordination by 2 Te + 2 Cl Agb1: almost regular tetrahedral coordination by 4 Te Agb2: trigonal-planar coordination by 3 Te [2+2] and [3+1] coordination[3+1] coordination

[3] and [4] Te-coordination 4 different types of silver coordination in the  -phase: Aga{1,2,3,4,5,8}: distorted tetrahedral coordination by 3 Te + 1 Cl Aga{6,7}: distorted tetrahedral coordination by 2 Te + 2 Cl Agb1: almost regular tetrahedral coordination by 4 Te Agb2: trigonal-planar coordination by 3 Te Ag 5 Q 2 X: Ag-coordination

Substitution of the anion sublattice Ag 5 Te 2 Cl

Substitution of the anion sublattice Ag 5 Te 2 Cl TeS TeSe Ag 5 Te 2-y S y Cl Ag 5 Te 2-z Se z Cl y = 0 – 0.3 z = 0 – 0.7 T. Nilges, C. Dreher, A. Hezinger, Solid State Sci., in press.

Substitution of the anion sublattice Ag 5 Te 2 Cl TeSClBr TeSe Ag 5 Te 2-y S y ClAg 5 Te 2 Cl 1-x Br x Ag 5 Te 2-z Se z Cl y = 0 – 0.3x = 0 – 0.65 z = 0 – 0.7 T. Nilges, C. Dreher, A. Hezinger, Solid State Sci., in press

Ag 5 Te 2 Cl 1-x Br x : DSC DSC in a temperature range from -150 °C to +100 °C phase transition  –  : transition temperature decreases with increasing x substitution has strong influence on the transition temperature, not detected any more for x = 0.4 and higher phase transition  –  : transition temperature increases with increasing x substitution has moderate influence on the transition temperature

Ag 5 Te 2 Cl 1-x Br x : DSC

Ag 5 Te 2-y S y Cl: DSC DSC in a temperature range from -150 °C to +100 °C phase transition  –  : not observed any more phase transition  –  : transition temperature decreases with increasing x substitution has strong influence on the transition temperature, not detected any more for y = 0.3 and higher

Ag 5 Te 2-y S y Cl: DSC

DTA from room temperature to 550 °C peritectic melting / decomposition melting points are decreased with increasing degree of substitution Ag 5 Q 2 X: DTA

Ag 5 Q 2 X: phase diagrams Ag 5 Te 2 Cl 1-x Br x Ag 5 Te 2-y S y Cl

Ag 5 Q 2 X: cell volumes powder XRD at room temperature and 363 K linear increase of lattice constants and cell volumes with increasing degree of substitution for both Ag 5 Te 2 Cl 1-x Br x and Ag 5 Te 2-y S y Cl Ag 5 Te 2 Cl 1-x Br x Ag 5 Te 2-y S y Cl error bars are drawn for +/- 3   -type  type  -type

impedance spectroscopy from 30 °C – 200 °C, = 100 mHz – 4 MHz slight increase of conductivity and activation energies with increasing x (Cl-Br-substitution) comparable conductivities and activation energies for Te-S-substitution; stabilization of the HT-  -phase at room temperature Ag 5 Q 2 X: electric conductivity x(Br)/y(S) E a (  )E a (  ) eV0.50 eV x(Br)= eV0.51 eV x(Br)= eV0.51 eV y(S)= eV-

Jpdf and opp-analysis of single crystal X-ray data calculated activation barriers show same magnitude and trend as results from impedance spectroscopy  -Ag 5 Te 2 Cl 1-x Br x : diffusion pathways Ag 5 Te 2 Cl isovalue Ag 5 Te 2 Cl 0.5 Br 0.5 isovalue 0.999

Dr. T. Nilges Prof. Dr. A. Pfitzner Prof. Dr. R. Pöttgen (University of Münster) Dr. M. Zabel, Dr. M. Andratschke, S. Stempfhuber D. Feil all other members of the Pfitzner workgroup Acknowledgements

Diffusion pathways in  -Ag 5 Te 2 Cl  -Ag 5 Te 2 Cl 1-x Br x : diffusion pathways

Diffusion pathways in  -Ag 5 Te 2 Cl 0.5 Br 0.5  -Ag 5 Te 2 Cl 1-x Br x : diffusion pathways