Evan L. Thomas

Phase compatibility and thermoelectric properties of compounds in the Sr–Ca–Co–O system

Two low-dimensional cobaltite series in the Sr–Ca–Co–O system have been investigated for their solid solution limit, structure, and compatibility phase relationships (850 °C in air). Thermoelectric properties have been measured for selected members of these solid solutions. In (Ca,Sr)3Co4O9, which has a misfit layered structure, Sr was found to substitute in the Ca site to a limit of (Ca0.8Sr0.2)3Co4O9. Compounds in the homologous series, An+2ConCo′O3n+3 [where A=Sr, Ca, (Ca,Sr), or (Sr,Ca)], consist of one-dimensional parallel Co2O66− chains that are built from successive alternating face-sharing CoO6 trigonal prisms and “n” units of CoO6 octahedra along the hexagonal c-axis. In the Can+2ConCo′O3n+3 series, only the n=1 phase (Ca3Co2O6) could be prepared under the present synthesis conditions. Sr substitutes in the Ca site of Ca3Co2O6 to a limit of (Ca0.9Sr0.1)3Co2O6. In the Srn+2ConCo′O3n+3 series, Ca substitutes in the Sr site of the n=2, 3, and 4 members to a limit of (Sr0.7Ca0.3)4Co3O9, (Sr0.67Ca0.33...

Neutron scattering measurements of the phonon density of states of FeSe 1 − x superconductors

Inelastic neutron-scattering experiments have been carried out on polycrystalline samples of the

Thermopower of Co-doped FeSe

{\text{FeSe}}_{1\ensuremath{-}x}

Statistical Analysis of a Round-Robin Measurement Survey of Two Candidate Materials for a Seebeck Coefficient Standard Reference Material.

superconductors. We report the phonon density of states for

Structural and thermoelectric properties of BaRCo4O7 (R = Dy, Ho, Er, Tm, Yb, and Lu)

{\text{FeSe}}_{1\ensuremath{-}x}

A High-Throughput Screening System for Thermoelectric Material Exploration Based on a Combinatorial Film Approach

with

Round-robin studies of two potential seebeck coefficient standard reference materials

{T}_{c}\ensuremath{\approx}8\text{ }\text{K}

Pressure-induced effects on the structure of the FeSe superconductor

. The phonon cutoff frequency is observed around 40 meV. No significant change is observed across the superconducting transition. The measurements support the published first-principles calculations [A. Subedi et al., Phys. Rev. B 78, 134514 (2008)].

Round-robin measurements of two candidate materials for a Seebeck coefficient Standard Reference Material™

The effect of cobalt doping on the thermopower of the superconductor FeSe is investigated through electrical and thermal transport measurements. Our results point to the destruction of superconductivity at very low Co concentrations. Thermopower data suggest negative charge carriers along with a large enhancement of the Seebeck coefficient, S, on the order of ≈−80 μV/K near T=100 K.

Development of a Seebeck coefficient Standard Reference Material

In an effort to develop a Standard Reference Material (SRM™) for Seebeck coefficient, we have conducted a round-robin measurement survey of two candidate materials—undoped Bi2Te3 and Constantan (55 % Cu and 45 % Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of different commercial and custom-built measurement systems and techniques. In this paper we report the detailed statistical analyses on the interlaboratory measurement results and the statistical methodology for analysis of irregularly sampled measurement curves in the interlaboratory study setting. Based on these results, we have selected Bi2Te3 as the prototype standard material. Once available, this SRM will be useful for future interlaboratory data comparison and instrument calibrations.