A key driver of cost for a thermoelectric generator is the thermoelectric materials themselves, and the heavy reliance on rare earth (RE) elements as fillers, particularly for p-type formulations, represents a strategic risk. In the present study, we have investigated fully filled p-type skutterudites with nominal compositions CaFexCo4 − xSb12 (2 ⩽ x ⩽ 3.5) using both experimental and theoretical methods. High purity samples were successfully synthesized using a combined melt-spinning (MS) and spark plasma sintering (SPS) technique. Structural analysis confirmed phase-pure samples with high filling fraction (>90%), homogeneous filler and transition metal distribution, and exceptionally low levels of oxygen contamination. Electrical and thermal transport property measurements revealed large power factors and unexpectedly low thermal conductivities. Electronic band structure calculations found a rapid increase in the density of states at the Fermi level with increasing Fe content. The large power factors observed in this system are attributable to this effect. Maximum zT of 0.9 was achieved in CaFe3CoSb12 at 773 K. To understand the low lattice thermal conductivity in these compounds, lattice dynamics calculations were performed. The small size of Ca atoms and their concomitantly weak interactions with the surrounding Sb atoms result in a small force constant between fillers and the host, giving rise to a heretofore unreported low frequency optical phonon mode. This low frequency mode at 7 meV is in addition to the previously described mode at 17 meV identified by modeling the Ca as a simple harmonic oscillator. The lower energy phonon mode imparted by Ca filling results in a comparable lattice thermal conductivity reduction to early lanthanide species such as La.

Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled YbxBayCo4Sb12 with ZT values around 1.1 at 750 K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique, has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434–448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.

About 18g of Ni0.05Mo3Sb5.4Te1.6 were prepared by heating the elements in the stoichiometric ratio at 1000K. The product was divided into four parts, and then C60 was added to three of these four parts at 1, 2, and 3mass%, respectively. Each part was hot-pressed at 150MPa and 923K. The sample with 1% C60 was characterized via a Rietveld refinement and TEM analyses. Measurements of the three thermoelectric key properties revealed that the Seebeck coefficient barely depends on the carbon amount added, while both the electrical and the thermal conductivity decrease with increasing amount of carbon. Depending on the amount of C60 used and on the temperature, the thermoelectric performance was either enhanced or decreased, depending on whether the electrical conductivity decreased less or more than the thermal conductivity. At the highest temperature measured, all carbon-containing samples performed better than the unmodified bulk sample, namely up to 14%. These improvements are within the error margin, however.

Various compositions of the thermoelectric material, silicon germanium (SiGe), were synthesized directly from single elements (SE) via the spark plasma sintering (SPS) process. Through proper choice of commercially available powders, sintering conditions and stoichiometry, n-type and p-type samples with thermoelectric properties comparable with those of the Si80Ge20 alloys used in radioisotope thermoelectric generators for space missions were generated using the SE SPS process. The SE SPS technique is a rapid process requiring only 1 h to synthesize the desired material. This new synthesis technique is a viable alternative to traditional synthesis methods and provides the potential to discover novel avenues for improving the thermoelectric dimensionless figure of merit of SiGe alloys.

Our study objective was to assess changes in effective contraceptive use among women at risk of unintended pregnancy in Florida in 2008 and 2009 compared with 2002 and 2004. Contraceptive use questions were available from Florida’s Behavioral Risk Factor Surveillance System (BRFSS) for both periods (n = 4,606). Log binomial regression was used with appropriate methods to account for complex sampling in the BRFSS. We examined the change in four effective contraceptive use groups: sterilization, long-acting reversible contraceptive (LARC), short-acting reversible contraceptive (SARC), and barrier methods. Prevalence ratios comparing the two time periods were adjusted by demographic characteristics, employment, insurance status, children at home, poverty level, health behaviors, and health status. No evidence of change was found in sterilization (Adjusted Prevalence Ratio APR = 0.96; 95 % CI: 0.84–1.10) or SARC (APR = 1.01; 95 % CI: 0.87–1.18). The overall use of LARC increased and use of barrier methods decreased significantly over the two periods (APR = 1.68; 95 % CI: 1.09–2.60 and APR = 0.77; 95 % CI: 0.61–0.98, respectively). Only two population groups experienced significant changes in prevalence in the four use groups over this period. Non-Hispanic White women increased their use of LARC (APR = 2.89; 95 % CI: 1.58–5.29) and women who have never been married decreased their use of barrier methods (APR = 0.51; 95 % CI: 0.33–0.77). Contraceptive use in Florida continues to be low overall with some shift towards more effective long-term methods. New efforts are needed to promote and increase family planning practices, which include the use of effective contraceptives.

Resistivity (ρ), Seebeck coefficient (α) and thermal diffusivity of the title compounds CaZn2P2, YbZn2P2, YbCuZnP2 and YbMnCuP2 are measured over a temperature range 300–1000 K to evaluate the thermoelectric potential of these materials. The temperature dependence of ρ and α of these light weight and less explored Zintl phosphides is similar to that of a degenerate semiconductor. While the electrical transport properties ρ and α are strongly composition dependent, thermal conductivity (κ) calculated from thermal diffusivity is remarkably low in the range 1.1–2.5 W m−1 K−1 at 1000 K. Room-temperature Hall resistance measured on selected samples suggests that holes dominate in the transport. The best composition appears to be YbZnCuP2 which has the combination of ρ ∼ 2.4 mΩ cm, α ∼ 160 µV K−1 and κ ∼ 1.7 W m−1 K−1 at 1000 K resulting in a ZT value of ∼0.6.

The hydrothermal growth of bulk single crystals of lutetium oxide (Lu2O3) is reported. Crystals were grown at 600-650 degrees C at 2 kbar in water with high concentrations (10-20 M) of KOH as a mineralizer. Under these conditions crystals formed spontaneously and could also be transported to suitable seeds to form large (3-8 mm/edge) single crystals. Experiments were done to optimize transport conditions and the quality of the crystals for the first time. The crystals were doped with trivalent laser active ions such as Er3+ and Yb3+. Absorption spectra of the doped materials were determined. Thermal conductivities of the pure single crystals as well as of the Yb-doped crystals were determined between room temperature and 77 K. The conductivity of the pure crystals increases significantly at lower temperatures as expected, and is significantly greater than that of YAG. The Yb-doped crystals have a thermal conductivity almost unchanged from the pure host, which is promising for use in high-energy laser applications.

As a narrow gap, strongly correlated electron semiconductor, FeSb2 single crystals can exhibit a colossal thermopower1 (on the order of −40,000 μV/K or greater) and a relatively high lattice thermal conductivity2 (over 300 W/m-K) at temperatures around 10 K. In this work, a series of FeSb2 polycrystalline samples with different amounts of additional Indium were prepared by a quench-and-anneal method followed by a spark plasma sintering procedure. The x-ray diffraction, scanning electron microscopy, and elemental analysis verified that the Sb/InSb nanoinclusions were formed in situ on the boundaries of coarse FeSb2 grains. The presence of such nanoinclusions and other as-formed multiscale microstructures can scatter phonons and thus dramatically reduce the corresponding lattice thermal conductivity. Furthermore, the electrical properties can be also improved because of the addition of high mobility carriers from the InSb nanoinclusions. Overall, FeSb2-based materials have shown some promising potential for possible thermoelectric cooling applications at cryogenic temperatures.

Winter is back in town and it's time to review the One-Stop Job Market's weather related closing policy. The Lower Shore Workforce Alliance (LSWA), as the landlord, sets the inclement weather closing policy for the One-Stop Job Market. LSWA has decided the One-Stop Job Market will follow the Wicomico County government administrative office's closing pol- icy. When inclement weather occurs and the counties' administrative office closes, the Job Market will close to the public. WBOC -TV and WMDT-TV will add the Job Market closing to their weather closings and postpone- ments list when the Wicomico county administrative office is closed or it's opening is delayed. Employees will be allowed to enter the building if it is closed to the public, but LSWA requests that all customer appointments, meetings, etc. be can- celled. It will be the responsibility of each partner agency to decide if their employees should report for work and how they will be notified. Please contact me or Kathy Strother at (410) 341-8533, Ext. 0 with weather related closing policy questions.

Single crystals of ThO2 exceeding 8 mm in length have been produced by hydrothermal synthesis in aqueous cesium fluoride solutions at 750 degrees C. Solubility studies have confirmed ThO2 is congruently saturating in aqueous cesium fluoride with positive solubility with respect to temperature and increasing mineralizer concentration. Bulk transport growth of ThO2 was performed to determine the viability of large-scale production of ThO2 single crystals for possible nuclear fuel applications. The thermal conductivity and thermal expansion properties of single crystal ThO2 were measured and are reported here for the first time. The single crystal sample, in regard to nuclear fuel applications, showed improved thermal performance compared with previously reported polycrystalline values.

Lead telluride (PbTe) nanocrystals have been synthesized using a chemical vapor deposition technique. The size-selective precipitation mechanism enables relatively good control of the particle size distribution by variation of the heating temperature, the Ar gas flow rate, and an admixture with Au particles. As the result, a high yield of several hundred milligrams of nanocrystals that exhibit rather narrow size distributions of 100, 200, and 600nm have been obtained. X-ray diffraction studies confirm the PbTe crystal structure and in addition find that the lattice constant monotonically increases with diminishing particle size.

Over a decade ago it was predicted that nano-scaled thermoelectric (TE) materials might have superior properties to that of their bulk counterparts. Subsequently, a significant increase in the figure of merit, ZT (ZT > 2), has been reported for nano-scaled systems such as superlattice and quantum dot systems constituently based on those more commonly used bulk TE materials (e.g., Bi2Te3 and PbTe). However, the challenge remains to achieve these higher performance results in bulk materials in order to more rapidly incorporate them into standard TE devices. Recent theoretical work on boundary scattering of phonons in amorphous materials indicates that micron and submicron grains could be very beneficial in order to lower the lattice thermal conductivity and yet not deteriorate the electron mobility. The focus in this paper will be to highlight some of our new directions in bulk thermoelectric materials research. Thermoelectric materials are inherently difficult to characterize and these difficulties are magnified at high temperatures. Specific materials will be discussed, especially those bulk materials that exhibit favorable properties for potential high temperature power generation capabilities. One potentially fruitful research direction is to explore whether hybrid TE materials possess possible enhanced TE properties. These “engineered” hybrids include materials that exhibit sizes from on the order of a few nanometers to hundreds of nanometers of the initial materials. These initial materials are then incorporated into a bulk structure. A discussion of some of the future research directions that we are pursuing is highlighted, including some bulk materials, which are based on nano-scaled or hybrid composites. The synthesis techniques and the synthesis results of many of these nano-scale precursor materials will be a primary focus of this paper.

The otherorhombic distorted perovskite La 1−x Sr x RuO 3 (0.1<x<0.9) polycrystalline samples have been prepared using conventional solid state chemistry reaction. The phase constituent, compositional homogeneity and micro-morphology were checked by X-ray powder diffraction, Energy Disperse X-ray spectroscopy and scanning electron microscopy before characterized by means of the electrical resistivity, thermal conductivity and thermal power measurements. Particularly, the compositional dependence of Seebeck coefficient of present compound was studied in light of the comparison with the strongly correlated system Na x CoO 4 and the relevant model proposed by W. Koshibae. Finally, the potential of using La 1−x Sr x RuO 3 as a practical thermoelectric material has been also discussed.

Borer, Drake S.; Starr, Adam J.; Reinert, Charles M.; Rao, Ashutosh V.; Weatherall, Paul; Thompson, Daniel; Champine, Julie; Jones, Alan L. Author Information

Borer, Drake S.*; Starr, Adam J.*; Reinert, Charles M.*; Rao, Ashutosh V.†; Weatherall, Paul†; Thompson, Daniel*; Champine, Julie†; Jones, Alan L.* Author Information

OBJECTIVES:In patients with pelvic or acetabular fractures, to compare the prevalence of pulmonary embolism in a time period without screening for deep vein thrombosis to that seen when a screening protocol was in place. DESIGN:Retrospective. SETTING:County hospital. PATIENTS:All patients with closed fractures of the pelvis or acetabulum treated during the study periods. INTERVENTION:Prophylaxis for deep vein thrombosis was the same for both groups. From November 1, 1997 though November 31, 1999, a screening protocol for deep vein thrombosis was employed using ultrasound and magnetic resonance venography. From January 1, 2000 through December 1, 2001, no screening was used. MAIN OUTCOME MEASUREMENT:Pulmonary emboli were recorded. RESULTS:The 1997 to 1999 time period included 486 patients with fractures of the pelvis or acetabulum; the 2000 to 2001 time period included 487. In the period when a screening protocol was in place, 10 patients (2%) were diagnosed with pulmonary embolism by pulmonary arteriogram, autopsy, or ventilation perfusion scan. All but 2 who were diagnosed with pulmonary embolism had undergone screening for deep vein thrombosis, and none of the screening tests were positive. In the 2000 to 2001 time period, when no screening for deep vein thrombosis was done, 7 patients (1.4%) were diagnosed with pulmonary embolism, by pulmonary arteriogram, autopsy, spiral computed tomography scan, or high clinical suspicion. There was no significant difference between the prevalence of pulmonary embolism seen in 1997 to 1999 and that seen in 2000 to 2001 (P = 0.48). CONCLUSION:Discontinuation of screening for the diagnosis of deep vein thrombosis did not change the rate of pulmonary embolism.

We analyze the thermal escape behavior of the metastable zero-voltage state in biased symmetric hysteretic interferometers in external magnetic fields. An effective single degree of freedom equation of motion for the system with small loop inductance is derived and used to evaluate the two necessary parameters, energy barrier and attempt frequency, for the successful application of Kramers theory for thermal escape from metastable states. The slightly revised theory, resulting in a double pendulum model of the interferometer, is outlined and numerical simulation results are used to validate the approach. Recent experimental reports of excessive thermal escape temperatures for interferometers are discussed and interpreted.