The solid solution series Tl(V1−xCrx)5Se8: crystal structure, magnetic and thermoelectric properties. Issue 40 (5th August 2015)

• Record Type: Journal Article
• Authors: Maier, Stefan; Lefèvre, Robin; Lin, Xinsong; Nunna, Raghavendra; Berthebaud, David; Hèbert, Sylvie; Mar, Arthur; Gascoin, Franck
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 40(2015)
• Page Start: 10509
• Page End: 10517
• Publication Date: 2015-08-05
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c5tc01766a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The crystal structure of single crystalline members of the solid solution series Tl(V1− x Cr x )5 Se8 ( x = 0–1 and Δ x = 0.2) was determined and the magnetic and thermoelectric properties of bulk TlV5 Se8 were investigated. Abstract : The crystal structure of single crystalline members of the solid solution series Tl(V1− x Cr x )5 Se8 ( x = 0–1 and Δ x = 0.2) was determined and the magnetic and thermoelectric properties of bulk TlV5 Se8 were investigated. All compounds crystallize in the pseudo-hollandite-type structure ( C 2/ m ) with a nonlinear increase in the unit cell volume due to a simultaneous increase/decrease in the transition metal distances across the edge/face-sharing octahedra. A slight Tl deficiency was found for single crystalline TlV5 Se8 and Tl(V0.8 Cr0.2 )5 Se8 as well as for bulk TlV5 Se8 according to Rietveld and single crystal structure refinements. The metallic character of bulk TlV5 Se8 and its low electrical resistivity compared to poly- and single-crystalline TlCr5 Se8 can probably be associated with this probable Tl deficiency. In TlV5 Se8, anomalies in the low temperature Seebeck coefficient, i.e. a maximum at T ∼ 14 K and two sign changes at T ∼ 47 K and T ∼ 167 K, were found. Bulk TlV5 Se8 is a highly frustrated ( f = | θ |/ T N ≈ 42 K) Curie–Weiss paramagnet ordering antiferromagnetically ( θ = −1287 K) below T N ≈ 31 K with an effective magnetic moment of μ = 2.68 μ B corresponding to V 3+ . Low-field M ( H ) measurements revealed the existence of a small ferromagnetic component below T N in bulk TlV5 Se8 and, despite the observed spin frustration, no spin glass phase was found in this compound.