Univerzita Pardubice Fakulta chemicko- technologická

Univerzita Pardubice

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Publikace detail

SnSe Doped with Tl and its Mechanical Properties

Autoři: Šraitrová Kateřina | Kucek Vladimír | Drašar Čestmír

Rok: 2018

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	SnSe Doped with Tl and its Mechanical Properties	Recently, SnSe has been studied as a promising thermoelectric material due to its high TE performance and low thermal conductivity [1]. Tin selenide belongs to the IV-VI group of semiconductors and it shows inherent p-type conductivity. At room temperature it shows Pnma space group with orthorhombic symmetry. Above 810 K this structure changes to Cmcm space group [2,3]. Record value ZT = 2.6 was measured along the b-axis in SnSe single crystal1. This value encouraged thermoelectric groups around the world to enhance figure of merit by doping. Huge number of doping studies appears each year. We studied the influence of Tl on thermoelectric properties of SnSe in polycrystalline form [4]. From our results it follows that Tl is a suitable dopant for enhancement of thermoelectric properties of SnSe. Thus, we decided to study its influence on single crystals. A series of single crystals Sn1-xTlxSe, where x = 0.0025, 0.005, 0.0075 and 0.01 was prepared. Samples were characterized by X-ray diffraction and measurements of electrical conductivity, Hall coefficient and Seebeck coefficient were performed over the temperature range 93 – 473 K. During the cutting of the samples from crystals we encountered difficulties with mechanical properties of doped material which undoped stoichiometric SnSe did not exhibit. Further difficulties manifested itself during soldering of the samples for measurements of Hall coefficient. Our samples fell into pieces along the oblique dislocations. These dislocations seem to have huge impact also on the growth of our single crystals, because Tl doped single crystals are very large in comparison with stoichiometric SnSe and seem to grow preferentially along them. Transport properties results suggest that dislocations influence our measurements. Samples with these dislocations show ~25 % higher electrical conductivity and ~10 % lower Seebeck coefficient. Dislocations have practically no impact on Hall coefficient and concentration of free charge carr