Crystal Structures and Thermal and Electrical Properties of the New Silver (poly)Chalcogenide Halides Ag23Te12Cl and Ag23Te12Br
datasetposted on 07.04.2008, 00:00 by Stefan Lange, Melanie Bawohl, Tom Nilges
Two new silver (poly)chalcogenide halides, Ag23Te12Cl and Ag23Te12Br, were characterized by powder X-ray phase analysis, energy dispersive X-ray analysis, and crystal structure determinations at various temperatures. Thermal analyses of both compounds and electrochemical measurements for the bromide completed the investigation. The compounds Ag23Te12X (X = Cl, Br) are isostructural and crystallize orthorhombically (space group Pnnm, Z = 4) as systematic twins. The lattice parameter values derived from X-ray powder data were a = 21.214(2) Å, b = 21.218(2) Å, c = 7.7086(7) Å, and V = 3469.8(6) Å3 for Ag23Te12Cl at 293 K and a = 21.170(1) Å, b = 21.170(1) Å, c = 7.7458(5) Å, and V = 3471.4(4) Å3 for Ag23Te12Br at 298 K. An enhanced silver ion mobility was revealed by impedance spectroscopy investigations. No phase transitions were observed in the temperature range 100−750 K. These two silver(I) (poly)chalcogenide halides are the second set of representatives of a new class of coinage-metal (poly)chalcogenide halides in which both covalently bonded [Te2]2− dumbbells and ionically bonded Te2− anions appear.
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Thermal analysesimpedance spectroscopy investigationsTe 2silver ion mobilitycrystal structure determinationspolyAg 23 Te 12 Cl293 Kcompounds Ag 23 Te 12 XNew SilverElectrical Propertiesphase transitions298 Kelectrochemical measurementsspace group Pnnmlattice parameter valuesAg 23 Te 12 Brcrystal Structures