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- Title
Doping GeSb<sub>2</sub>Te<sub>4</sub> with Cr<sup>3+</sup>: Structure and Temperature-Dependent Physical Properties.
- Authors
Welzmiller, Simon; Schlegel, Robert; Pöppl, Andreas; Bothmann, Georg; Scheidt, Ernst‐Wilhelm; Scherer, Wolfgang; Oeckler, Oliver
- Abstract
The tellurides Ge0.94Cr0.04Sb2Te4 and Ge0.88Cr0.08Sb2Te4 were synthesized in sealed silica glass ampoules. Rietveld refinements show that they crystallize in the 21 R-In3Te4 structure type ( R $\bar{3}$ m), similar to undoped GeSb2Te4. The composition and phase purity were confirmed by ICP-AES as well as by SEM and TEM, including EDX measurements. EPR spectroscopy reveals the valence state +III for the Cr atoms ( g = 1.990) in Ge0.88Cr0.08Sb2Te4, which agrees well with the Cr3+ content calculated from the inverse magnetic susceptibility. The material exhibits a ferromagnetic fluctuations with a paramagnetic Curie temperature of 70 K ± 20 K and is a metallic conductor. Compared to GeSb2Te4, the electrical conductivity is increased by a factor of 2.5. As Cr doping further leads to a higher Seebeck coefficient, the thermoelectric figure of merit ZT reaches values of up to 0.3 at 500 °C, i.e. three times the value of undoped material.
- Subjects
THERMOELECTRICITY; MAGNETIC properties; TELLURIDES; DOPING agents (Chemistry); SOLID solutions; CHALCOGENIDES
- Publication
Zeitschrift für Anorganische und Allgemeine Chemie, 2015, Vol 641, Issue 12/13, p2350
- ISSN
0044-2313
- Publication type
Article
- DOI
10.1002/zaac.201500574