synthesis-non-uniformly-pr-doped-srtio3-ceramics-their-thermoelectric

Synthesis of Non-uniformly Pr-doped SrTiO<sub>3</sub> Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

Clemson University

Quaternary chalcogenides, particular compounds with the stannite structure-type, are of interest for thermoelectrics applications however tellurium-containing compositions have not been extensively investigated. We report on the synthesis and high temperature thermoelectric properties of p-type stannites Cu2.2Zn0.8SnSe4-xTex (x = 0.1, 0.2, 0.3, and 0.4). The compositions for each specimen were confirmed with a combination of Rietveld refinement and elemental analysis. Hall measurements indicate that holes are the dominant charge carriers in these materials. The electrical resistivity shows little temperature dependence up to 500 K and then increases with increasing temperature. The thermal conductivity decreases with increasing temperature with no indication of increase at higher temperatures suggesting a minimal bipolar diffusion effect in the thermal conductivity although these materials possess relatively small band-gaps as compared to that of other stannite compositions. A maximum ZT value of 0.56 was obtained at 700 K for Cu2.2Zn0.8SnSe3.7Te0.3 due to a relatively high Seebeck coefficient and low thermal conductivity.

Synthesis, crystal structure, and transport properties of Cu2.2Zn0.8SnSe4-xTex (0.1 ≤ x ≤ 0.4).

Single crystals of the ternary clathrate-I Na8Al8Si38 were synthesized by kinetically controlled thermal decomposition (KCTD), and microcrystalline Na8Al8Si38 was synthesized by spark plasma sintering (SPS) using a NaSi + NaAlSi mixture as the precursor. Na8AlxSi46-x compositions with x ≤ 8 were also synthesized by SPS from precursor mixtures of different ratios. The crystal structure of Na8Al8Si38 was investigated using both Rietveld and single-crystal refinements. Temperature-dependent transport and UV/vis measurements were employed in the characterization of Na8Al8Si38, with diffuse-reflectance measurement indicating an indirect optical gap of 0.64 eV. Our results indicate that, when more than one precursor is used, both SPS and KCTD are effective methods for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques.

Article	Year
Synthesis, crystal structure, and transport properties of Cu2.2Zn0.8SnSe4-xTex (0.1 ≤ x ≤ 0.4). Dalton transactions (Cambridge, England : 2003)\| PubMed ID: 25883041	2015
Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi. Inorganic chemistry\| PubMed ID: 25985168	2015

Xiaoyu Zeng

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