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Complex Oxides for Highly Efficient Solid-State Energy Conversion

IB-2400

APPLICATIONS OF TECHNOLOGY:

•  Power generation through waste heat recovery

  • Automobiles
  • Power plants
  • Factories producing glass, steel, and iron

• Refrigeration

  • Refrigerators
  • Air conditioning
  • Automobile heating and cooling
  • Cooling of microprocessor hotspots, electronics, and optical components

ADVANTAGES:

  • Non-toxic
  • More efficient, cheaper and safer than bismuth telluride systems
  • Tunability in thermoelectric properties
  • Can be used with a variety of energy sources
  • Can provide heating and cooling
  • Operate on macro/nano scale
  • Obviates need for hazardous fluids, complicated moving parts
  • Higher efficiency, owing to better conductivity, thermopower, and thermal conductivity

ABSTRACT:

The search for highly efficient thermoelectric materials has become particularly critical at a time of rising global energy prices. Significant energy savings could be realized with the use of solid-state thermoelectric energy conversion devices both for thermoelectric power generation and for cooling, and their use in the recovery of waste heat opens up an array of potential applications.

Arun Majumdar, Ramamoorthy Ramesh and colleagues at Lawrence Berkeley National Laboratory and UC Berkeley have developed a series of nontoxic thermoelectric systems using complex oxides, with strontium titanate as a model.

Using complex oxides to directly convert thermal to electrical energy is both safer and cheaper than using bismuth telluride systems, whose many disadvantages have led to an impasse in solid-state conversion.

Complex oxides offer wide thermoelectric tunability, and their large, effective mass of electrons enhances thermopower. Such devices need no hazardous fluids and complicated moving parts, and they can be adapted to large-scale uses as well as to miniaturization.   The Berkeley Lab invention also promises advancements in the development of microprocessors and optical components, whose progress has been slowed by problems with heat transport.

The invention involves doping the oxides with lanthanum and intentionally making oxygen vacancies, which significantly increases their conductivity and reduces thermal conductivity by scattering phonons. A substrate including a complex oxide can optionally be embedded with or layered over with a second nanostructured complex oxide. With optimal electrical conductivity, thermopower, and thermal conductivity, the devices could potentially approach a ZT figure-of-merit of 1 at high temperatures.

STATUS:

  • Published PCT Patent Application WO2008/109564 available at www.wipo.int and 12/539,135 available at www.uspto.gov. Available for licensing or collaborative research.

To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.

FOR MORE INFORMATION:

Yu, Choongho Yu, Matthew L. Scullin, Mark Huijben, Ramamoorthy Ramesh, and Arun Majumdar,   "Thermal conductivity reduction in oxygen-deficient strontium titanates," Appl. Phys. Lett. 92 , 191911 (2008); DOI:10.1063/1.2930679  

REFERENCE NUMBER: IB- 2400

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