Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena found both in bulk samples containing nanoscale constituents and in nanoscale samples themselves. Prior theoretical and experimental proof-of-principle studies on quantum-well superlattice and quantum-wire samples have now evolved into studies on bulk samples containing nanostructured constituents prepared by chemical or physical approaches. In this Review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications, thus bringing together low-dimensional and bulk materials for thermoelectric applications. Particular emphasis is given in this Review to the ability to achieve 1) a simultaneous increase in the power factor and a decrease in the thermal conductivity in the same nanocomposite sample and for transport in the same direction and 2) lower values of the thermal conductivity in these nanocomposites as compared to alloy samples of the same chemical composition. The outlook for future research directions for nanocomposite thermoelectric materials is also discussed.

https://www.bc.edu/content/dam/files/schools/cas_sites/physics/pdf/Ren/AdvMater_19_1043_2007.pdf

New Directions for Low-Dimensional Thermoelectric Materials**

The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system AgPb m SbTe 2+ m may be suitable for this purpose. With m = 10 and 18 and doped appropriately, n -type semiconductors can be produced that exhibit a high thermoelectric figure of merit material ZT max of ∼2.2 at 800 kelvin. In the temperature range 600 to 900 kelvin, the AgPb m SbTe 2+ m material is expected to outperform all reported bulk thermoelectrics, thereby earmarking it as a material system for potential use in efficient thermoelectric power generation from heat sources.

http://science.sciencemag.org/content/sci/303/5659/818.full.pdf

Cubic AgPbmSbTe2+m: Bulk Thermoelectric Materials with High Figure of Merit

Herein we cover the key concepts in the field of thermoelectric materials research, present the current understanding, and show the latest developments. Current research is aimed at increasing the thermoelectric figure of merit (ZT) by maximizing the power factor and/or minimizing the thermal conductivity. Attempts at maximizing the power factor include the development of new materials, optimization of existing materials by doping, and the exploration of nanoscale materials. The minimization of the thermal conductivity can come through solid-solution alloying, use of materials with intrinsically low thermal conductivity, and nanostructuring. Herein we describe the most promising bulk materials with emphasis on results from the last decade. Single-phase bulk materials are discussed in terms of chemistry, crystal structure, physical properties, and optimization of thermoelectric performance. The new opportunities for enhanced performance bulk nanostructured composite materials are examined and a look into the not so distant future is attempted.

New and Old Concepts in Thermoelectric Materials

An introduction to heat transfer

A class of thermoelectric materials has been synthesized with a thermoelectric figure of merit ZT (where T is temperature and Z is a function of thermopower, electrical resistivity, and thermal conductivity) near 1 at 800 kelvin. Although these materials have not been optimized, this value is comparable to the best ZT values obtained for any previously studied thermoelectric material. Calculations indicate that the optimized material should have ZT values of 1.4. These ternary semiconductors have the general formula RM4X12 (where R is lanthanum, cerium, praseodymium, neodymium, or europium; M is iron, ruthenium, or osmium; and X is phosphorus, arsenic, or antimony) and represent a new approach to creating improved thermoelectric materials. Several alloys in the composition range CeFe4-xCoxSb12 or LaFe4-xCoxSb12 (0 < x < 4) have large values of ZT.

https://science.sciencemag.org/content/sci/272/5266/1325.full.pdf

Filled Skutterudite Antimonides: A New Class of Thermoelectric Materials

A monolithic vapor chamber heat dissipating device uses a phase change liquid and one or more wicks to dissipate heat from a heat-generating system. The phase change liquid and one or more wicks may be directly coupled to the heat-generating system, or may be coupled to an intermediate evaporator substrate. The phase change liquid vaporizes as it absorbs heat from the heat-generating system. When the vapor rises and encounters a condenser substrate, the vapor condenses and transfers the heat to the condenser substrate. The condensed vapor is drawn by gravity and the one or more wicks to the phase change liquid coupled to the heat-generating system.

Monolithic phase change heat sink

To provide a monolithic phase change heat dissipating device.SOLUTION: A monolithic vapor chamber heat dissipating device uses a phase change liquid 13 and one or more wicks 11 to dissipate heat from a device substrate 7. The phase change liquid 13 and one or more wicks 11 may be directly coupled to the device substrate 7, or may be coupled to an intermediate evaporator substrate. The phase change liquid 13 vaporizes as it absorbs heat from the device substrate 7. When the vapor rises and encounters a condenser substrate 3, the vapor condenses and transfers the heat to the condenser substrate 3. The condensed vapor is drawn by gravity and the one or more wicks 11 to the phase change liquid 13 coupled to the device substrate 7.SELECTED DRAWING: Figure 1

Monolithic phase change heat dissipating device

Isolators for high frequency signals transmitted between two circuits configured to operate at different voltage domains are provided. The isolators may include resonators capable of operating at high frequencies with high transfer efficiency, high isolation rating, and a small substrate footprint. In some embodiments, the isolators may operate at a frequency not less than 20 GHz, not less than 30 GHz, not less than 65 GHz, or between 20 GHz and 100 GHz, including any value or range of values within such range. The isolators may include inductive loops with slits and capacitors integrally formed at the slits. The sizes and shapes of the inductive loops and capacitors may be configured to control the values of equivalent inductances and capacitances of the isolators. The isolators are compatible to different fabrication processes including, for example, micro-fabrication and PCB manufacture processes.

High frequency galvanic isolators

Ein Isolatorsystem weist einen Isolator, welcher differentielle Isolatorsignale erzeugt, und einen Empfanger, welcher digitale Daten erzeugt, die reprasentativ fur vom Isolator empfangene Signale sind, auf. Das System kann auch einen RC-Filter umfassen, welcher zwischen dem Isolator und dem Empfanger gekoppelt ist. Wahrend des Betriebs kann der Filter Transientensignale uber verschiedene Schaltungspfade im Isolator verteilen, von denen nur einige mit den Empfangereingangen gekoppelt sind. Im Laufe der Zeit kann der Filter Transientenbeitrage an den Empfangereingangen dampfen. Auf diese Weise kann der Filter Effekte dieser Gleichtakttransienten begrenzen.

Signalisolatorsystem mit Schutz für Gleichtakttransienten

Embodiments of the present disclosure may provide a circuit comprising a tank circuit. The tank circuit may include an inductor having a pair of terminals, a first pair of transistors, and a first pair of capacitors. Each transistor may be coupled between a respective terminal of the inductor and a reference voltage along a source-to-drain path of the transistor. Each capacitor may be provided in a signal path between an inductor terminal coupled to a respective first transistor in the first pair and a gate of a second transistor in the first pair.

Baoxing Chen

Papers

Monolithic phase change heat sink

Monolithic phase change heat dissipating device

High frequency galvanic isolators

Signalisolatorsystem mit Schutz für Gleichtakttransienten

Tank circuit and frequency hopping for isolators