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The main obstacle to improving the thermoelectric efficiency of a material arises from the common interdependence of electrical and thermal conductivity, whereas one ideally wants to raise the former while lowering the latter: a simple layered crystalline material -- SnSe -- is now reported that seems to have these qualities built in. Impressive thermoelectric performance from SnSe crystals Thermoelectric materials hold promise as a practical means of converting waste heat into electrical energy, but the energy-conversion efficiency of existing materials tends to be rather low. The main obstacle to improving the thermoelectric efficiency of a material arises from the common interdependence of electrical and thermal conductivity. Thermoelectric efficiency demands high electrical but low thermal conductivity and one route that might provide that combination is nanostructuring. Now Li-Dong Zhao and colleagues describe a simple layered crystalline material, tin selenide (SnSe), that appears to have these qualities built in. The authors identify features in the bonding structure of this material that they believe to be responsible, and suggest that these might help to guide the discovery of other candidate materials for high thermoelectric performance. The thermoelectric effect enables direct and reversible conversion between thermal and electrical energy, and provides a viable route for power generation from waste heat. The efficiency of thermoelectric materials is dictated by the dimensionless figure of merit, ZT (where Z is the figure of merit and T is absolute temperature), which governs the Carnot efficiency for heat conversion. Enhancements above the generally high threshold value of 2.5 have important implications for commercial deployment.sup.1,2, especially for compounds free of Pb and Te. Here we report an unprecedented ZT of 2.6 [plus or minus] 0.3 at 923 K, realized in SnSe single crystals measured along the b axis of the room-temperature orthorhombic unit cell. This material also shows a high ZT of 2.3 [plus or minus] 0.3 along the c axis but a significantly reduced ZT of 0.8 [plus or minus] 0.2 along the a axis. We attribute the remarkably high ZT along the b axis to the intrinsically ultralow lattice thermal conductivity in SnSe. The layered structure of SnSe derives from a distorted rock-salt structure, and features anomalously high Grüneisen parameters, which reflect the anharmonic and anisotropic bonding. We attribute the exceptionally low lattice thermal conductivity (0.23 [plus or minus] 0.03 W m.sup.-1 K.sup.-1 at 973 K) in SnSe to the anharmonicity. These findings highlight alternative strategies to nanostructuring for achieving high thermoelectric performance., Author(s): Li-Dong Zhao [sup.1] , Shih-Han Lo [sup.2] , Yongsheng Zhang [sup.2] , Hui Sun [sup.3] , Gangjian Tan [sup.1] , Ctirad Uher [sup.3] , C. Wolverton [sup.2] , Vinayak [...]

The thermoelectric effect enables direct and reversible conversion between thermal and electrical energy, and provides a viable route for power generation from waste heat. The efficiency of thermoelectric materials is dictated by the dimensionless figure of merit, ZT (where Z is the figure of merit and Tis absolute temperature),which governs the Carnot efficiency for heat conversion. Enhancements above the generally high threshold value of 2.5 have important implications for commercial deployment (1,2), especially for compounds free of Pb and Te. Here we report an unprecedented ZT of 2.6 [+ or -] 0.3 at 923 K, realized in SnSe single crystals measured along the b axis of the room-temperature orthorhombic unit cell. This material also shows a high ZT of 2.3 ± 0.3 along the c axis but a significantly reduced ZT of 0.8 ± 0.2 along the a axis. We attribute the remarkably high ZT along the b axis to the intrinsically ultralow lattice thermal conductivity in SnSe. The layered structure of SnSe derives from a distorted rock-salt structure, and features anomalously high Gruneisen parameters, which reflect the anharmonic and anisotropic bonding. We attribute the exceptionally low lattice thermal conductivity (0.23 ± 0.03 W [m.sup.-1] [K.sup.-1] at 973 K) in SnSe to the anharmonicity. These findings highlight alternative strategies to nanostructuring for achieving high thermoelectric performance., The efficiency of thermoelectric materials and devices is determined by the dimensionless figure of merit (ZT), defined as ZT = ([S.sup.2] σ/κ)T, where S, σ and κ are the Seebeck [...]

With about two-thirds of all used energy being lost as waste heat, there is a compelling need for high-performance thermoelectric materials that can directly and reversibly convert heat to electrical [...]

Penrose C. Albright, former Assistant Secretary for Science and Technology, Department of Homeland Security (DHS), was lead speaker for the Materials Applications for Homeland Security session at the Materials Science […]

A nondestructive imaging method, scanning near-field ultrasound holography (SNFUH), has been developed that provides depth information as well as spatial resolution at the 10- to 100-nanometer scale. In SNFUH, the phase and amplitude of the scattered specimen ultrasound wave, reflected in perturbation to the surface acoustic standing wave, are mapped with a scanning probe microscopy platform to provide nanoscale-resolution images of the internal substructure of diverse materials. We have used SNFUH to image buried nanostructures, to perform subsurface metrology in microelectronic structures, and to image malaria parasites in red blood cells., Nondestructive real-space imaging of deeply buried or embedded structures and features with lateral resolution below ~100 nm is a formidable challenge (1-5). Conventional imaging with noninvasive radiation, such as light [...]

Research was conducted to examine La4Cu3MoO12, a novel cuprate with mixed B-cations having a ratio of 1:3. Its synthesis was observed under ambient pressure phase which is fascinating due to its striking resemblances and differences with other cuprate systems. Its magnetism was calculated from 2 to 800 K. The La4Cu3MoO12 structure is the most unprecedented of the analogous lanthanide phases since lanthanum is the largest and because it forms at all.

Author(s): Li-Dong Zhao [1]; Shih-Han Lo [2]; Yongsheng Zhang [2]; Hui Sun [3]; Gangjian Tan [1]; Ctirad Uher [4]; C. Wolverton [2]; Vinayak P. Dravid [2]; Mercouri G. Kanatzidis (corresponding [...]

The design, synthesis, processing and dielectric properties of novel cross-linked inorganic/organic hybrid blend (CHB) dielectric films which allow low-voltage organic thin-film transistor (OTFT) operation are reported. The findings for the morphologies and microstructures of representative semiconductor films grown on CHB dielectrics prepared with incrementally varied compositions and processing conditions are found to correlate closely with the OTFT response.

The possible mechanisms of phonon scattering by nanostructures and defects in PbTe-X (X = 2%Sb, Bi, or Pb) thermoelectric materials systems are examined. The particle-induced local elastic perturbations have interfered with the phonon propagation pathway, thereby contributing to the reduction in lattice thermal conductivity and increasing the overall thermoelectric figure of merit.

The effect of Cd substitution on the thermoelectric properties of PbTe is examined in order to test if Cd atoms on Pb sites of the rock salt lattice can increase the Seebeck coefficient via the formation of a resonance level in the density of states near the Fermi energy. The studies have shown that samples have followed the Pisarenko relationship and a maximum thermoelectric figure of merit ZT is achieved for the PbTe-CdTe-Pb[I.sub.2] sample arising from a high power factor and a very low lattice thermal conductivity.

The advanced transmission electron microscopy technique is employed to explain the composition, as well as the structure and properties of different thermoelectric materials. The impact of nanostructuring and lattice strain on the photon transport taking place in the [NaPb.sub.18-x][Sn.sub.x][BiTe.sub.20] thermoelectric materials is also explained.

The synthesis, microstructure, and transport properties of composite thermoelectric materials based on the eutectic phase relationship between PbTe and Ge is reported. The results showed that the electrical transport and thermoelectric properties of the composites could be tuned and optimized through the use of hypereutectic compositions and alloying of Ge with Si.

The design, synthesis and structural characterization of a series of low-melting and thermally stable cadmium metal-organic chemical vapor deposition (MOVCD) precursors are discussed. The epitaxial growth of CdO films provides an approach to extremely high performance thin-film transparent conducting oxide (TCO) materials for high-end applications utilizing an efficient and scalable deposition technique.

An efficient approach for the construction of miniaturized semiconductor chemical sensors is described which exploits the capabilities of dip-pen nanolithography (DPN) in site-specific and multiple ink patterning. The first step towards an elaborate construction of a multitude of sensors for the on-site and real-time detection of hazardous gas species is a sensor array with eight miniaturized sensors.

A new method for direct patterning of organic/inorganic composite nanostructures on silicon is described. The sol patterning process offers higher resolutions and the ability to make multicomponent nanostructures with high registry.

Nature 489, 414-18(2012); doi:10.1038/nature11439 In this Letter, the units of thermal conductivity on the y-axes of Fig. 2d and e should be W m 1K 1 and the y-axis label [...]