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Stefan Lange Institute of Inorganic Chemistry University of Regensburg

Stefan Lange Institute of Inorganic Chemistry University of Regensburg. Variation of physical properties of silver(I) chalcogenide halides by modification of the anion substructure. NRW Graduate School of Chemistry, 25.–27.08.2004. Ag 5 Te 2 Cl: Structures.

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Stefan Lange Institute of Inorganic Chemistry University of Regensburg

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  1. Stefan Lange Institute of Inorganic Chemistry University of Regensburg Variation of physical properties of silver(I) chalcogenide halides by modification of the anion substructure NRW Graduate School of Chemistry, 25.–27.08.2004

  2. Ag5Te2Cl: Structures • Ag5Te2Cl is a trimorphic compound: -Ag5Te2Cl -Ag5Te2Cl -Ag5Te2Cl monoclinic (P 21/c) monoclinic (P 21/n) tetragonal (I 4/mcm) a=1935.9(1) pm a=1385.2(3) pm a=974.9(2) pm b=771.3(1) pm b=766.3(2) pm c=1953.3(1) pm c=1366.1(3) pm c=783.6(2) pm Z=16 Z=8 Z=4 =90.6(1)° =90.09(1)° (193 K) (298 K, powder XRD) (363 K, powder XRD) 334 K 241 K 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, 89-93. T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, 806-812.

  3. Ag5Te2Cl: Structures Anion substructure: a b g • minor distortion of the anion sublattice upon phase transition a-b-g • description as alternating nets in projection along selected crystallographic axes: • 44 for Cl and 32434 for Te T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, 806-812.

  4. Ag5Te2Cl: Structures Anion substructure: a b g • minor distortion of the anion sublattice upon phase transition a-b-g • description as alternating nets in projection along selected crystallographic axes: • 44 for Cl and 32434 for Te T. Nilges, S. Nilges, A. Pfitzner, Th. Doert, P. Böttcher, Chem. Mater., (2004), 16, 806-812.

  5. Ag5Te2Cl: Structures Anion substructure: a b g

  6. Ag5Te2Cl: Structures

  7. Ag5Q2X: Ag-coordination 4 different types of silver coordination in the b-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

  8. Ag5Q2X: Ag-coordination 4 different types of silver coordination in the b-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 [3] and [4] Te-coordination

  9. Substitution of the anion sublattice Ag5Te2Cl

  10. Substitution of the anion sublattice Ag5Te2Cl Te S Te Se Ag5Te2-ySyCl Ag5Te2-zSezCl y = 0 – 0.3 z = 0 – 0.7 T. Nilges, C. Dreher, A. Hezinger, Solid State Sci., in press.

  11. Substitution of the anion sublattice Ag5Te2Cl Te S Cl Br Te Se Ag5Te2-ySyCl Ag5Te2Cl1-xBrx Ag5Te2-zSezCl y = 0 – 0.3 x = 0 – 0.65 z = 0 – 0.7 T. Nilges, C. Dreher, A. Hezinger, Solid State Sci., in press

  12. Ag5Te2Cl1-xBrx: DSC

  13. Ag5Te2-ySyCl: DSC

  14. Ag5Q2X: phase diagrams Ag5Te2Cl1-xBrx Ag5Te2-ySyCl

  15. Ag5Q2X: 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 Ag5Te2Cl1-xBrx and Ag5Te2-ySyCl a-type a-type b-type a-type Ag5Te2Cl1-xBrx Ag5Te2-ySyCl error bars are drawn for +/- 3 s

  16. Ag5Q2X: electric conductivity • 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-a-phase at room temperature

  17. b-Ag5Te2Cl1-xBrx: diffusion pathways • Jpdf and opp-analysis of single crystal X-ray data • calculated activation barriers show same magnitude and trend as results from impedance spectroscopy Ag5Te2Cl isovalue 0.999 Ag5Te2Cl0.5Br0.5 isovalue 0.999

  18. Acknowledgements • 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

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