ChemInform Abstract: The Influence of Mn Doping on the Properties of Ge₄Sb₂Te₇.

Abstract

The Mn-doped compounds Ge 3MnSb2Te7 and Ge3.5Mn0.5Sb2Te7 are prepared from stoichiometric mixtures of the elements (silica ampules, 950 C for 24 h, quenching and subsequent annealing at 550 C for 96 h). The samples are characterized by powder and single crystal XRD, SEM, TEM, EPR, electrical conductivity, Seebeck coefficient, and magnetic measurements. The two compounds crystallize in the cubic space group Fm3m with Z = 4. Mn doping reduces the electrical conductivity of Ge4Sb2Te7, while the Seebeck coefficient increases significantly. The thermoelectric figures of merit of the Mn doped samples do not reach significantly more than 0.5 at any temperature. -(WELZMILLER, S.; HEINKE, F.; HUTH, P.; BOTHMANN, G.; SCHEIDT, E.-W.; WAGNER, G.; SCHERER, W.; POEPPL, A.; OECKLER*, O.; J. Alloys Compd. 652 (2015) 74-82, http://dx.

Layered manganese bismuth tellurides with GeBi4Te7- and GeBi6Te10-type structures: towards multifunctional materials

“…24 Mn doping and its influence on the thermoelectric properties was also reported for the layered compound Ge 4 Sb 2 Te 7 crystallizing with a Ge 3 As 2 Te 6 -type structure. 30 MnBi 2 Te 4 has been reported to be the first compound of the series MTe(Bi 2 Te 3 ) n where M is a transition metal represented by manganese. 31 Single-crystal data of MnBi 2 Te 4 revealed Mn/Bi antisite disorder; the magnetic properties are strongly anisotropic and antiferromagnetic ordering is observed below 24 K. 32,33 Investigations on the tentative phase diagram of the system Mn/Bi/Te indicated that there are further layered compounds in that system, 34 and estimates concerning their structures were suggested based on the interpretation of multi-phase powder diffraction patterns.…”

Layered Manganese Bismuth Tellurides with GeBi4Te7– and GeBi6Te10–type Structures: Towards Multifunctional Materials

“…24 Mn doping and its influence on the thermoelectric properties was also reported for the layered compound Ge 4 Sb 2 Te 7 crystallizing with a Ge 3 As 2 Te 6 -type structure. 30 MnBi 2 Te 4 has been reported to be the first compound of the series MTe(Bi 2 Te 3 ) n where M is a transition metal represented by manganese. 31 Single-crystal data of MnBi 2 Te 4 revealed Mn/Bi antisite disorder; the magnetic properties are strongly anisotropic and antiferromagnetic ordering is observed below 24 K. 32,33 Investigations on the phase diagram of the system Mn/Bi/Te indicated that there are further layered compounds in that system, 34 and estimates concerning their structures were suggested.…”

Cobalt germanide precipitates indirectly improve the properties of thermoelectric germanium antimony tellurides

“…In the GST class of materials, many elements are suitable for substitution, e.g. Mn, 41 Sn, 42 Cd, 43 Li, 44,45 Ag, 46 or Cr 47 replacing Ge; As 48 or In 49,50 replacing Sb, and Se 35 replacing Te. These substitutions change the electronic structure and charge carrier density and thus influence the thermoelectric performance.…”