Thermoelectric Material

VACOTHERM

VACOTHERM®  is a thermoelectric material used for direct conversion of heat into electricity.

Benefits:

  • ZT values approx. 0.9 @ 500°C
  • Hf-free intermetallic compounds, earth abundant raw materials
  • Matching thermal expansion coefficients for low thermal stresses
  • High temperature stability
  • High mechanical strength
  • High resistance to oxidation
  • Scalable manufacturing process

Details

Direct conversion of heat into electricity in thermoelectric generators (TEG) used for

  • Exhaust energy recovery in automotive or heavy duty vehicles
  • Waste heat recovery in industrial applications
  • Improving efficiency in combined heat and power plants
  • Self-sufficient energy supplies  

VACOTHERM are two differently doped Hafnium (Hf-) free half-Heusler intermetallic compounds.

VACOTHERM n and VACOTHERM p are our n-type and p-type semiconducting thermoelectric materials.

Both perfectly match  

  • in terms of thermal expansion coefficients
  • stable at high temperatures
  • most efficient above 300°C
  • characterized by a high mechanical strength

Efficient TE-materials need:

  • high Seebeck-coeffizient S
  • high electrical conductivity σ 
  • low thermal conductivity  κ

Material Properties (typical values) @ room temperature

Alloy Seebeck-Coefficient
S [µV/K]
Electric Conductivity
σ  [S/cm]
Thermal Conductivity 
 κ  [W/(m·K)]

Density
ρ [g/cm3]

Heat Capacity
Cp [J/(g ·K)]
VACOTHERM n -145 3,500 5.5 7.4 0.31
VACOTHERM p 110 3,500 7.2 8.1 0.29

Today, thermoelectric power generation gains importance in the context of direct conversion of thermal energy into electrical energy. Applications are exhaust energy recovery in automotive or heavy duty vehicles, waste heat recovery in industry or improving efficiency in combined heat and power plants. The typical operating principle of a thermoelectric generator (TEG) is shown opposite. The main advantages of this direct energy conversion are that no mechanical or chemical processes and no moving parts, liquids or gases are needed. The devices are robust, compact and maintenance free.

The recently developed thermoelectric materials VACOTHERM are Hafnium (Hf-) free half-Heusler intermetallic compounds. There are two differently doped types of VACOTHERM®: VACOTHERM n and VACOTHERM p are our n-type and p-type semiconducting thermoelectric materials. Both intermetallic compounds match perfectly in terms of thermal expansion coefficients, are stable at high temperatures, most efficient above 300°C and are characterized by a high mechanical strength.    

The working mechanism of VACOTHERM materials - used in TEG - is based on the Seebeck-effect: when placed in a temperature gradient, the materials generate a useable electric voltage.

The ability of a thermoelectric material to convert heat into electricity is expressed by its figure of merit ZT. 


In order to realize high ZT-values, the combination of a high Seebeck coefficient S with high electric conductivity σ and low thermal conductivity κ is necessary. This unique set of properties could be realized in our VACOTHERM materials.

With ZT-values of 0,9 @ 500 °C VACOTHERM is tailored for optimum efficiency at higher temperatures, where conventional Bismuth-Telluride thermoelectric materials fail. This makes them ideal candidates for many waste heat recovery applications.

Typical material properties such as Seebeck-coefficient, electric conductivity and thermal conductivity of VACOTHERM n and VACOTHERM p are shown.

Forms of supply

Standard form of supply:                          small blocks typically 1-2 mm per dimension

Optional coating of contact surfaces:   nickel or gold available
                                                                      other coatings possible - on request 

Other shapes and formats:                      custom-tailored geometries possible - on request

Direct conversion of heat into electricity in thermoelectric generators (TEG) used for

  • Exhaust energy recovery in automotive or heavy duty vehicles
  • Waste heat recovery in industrial applications
  • Improving efficiency in combined heat and power plants
  • Self-sufficient energy supplies  

VACOTHERM are two differently doped Hafnium (Hf-) free half-Heusler intermetallic compounds.

VACOTHERM n and VACOTHERM p are our n-type and p-type semiconducting thermoelectric materials.

Both perfectly match  

  • in terms of thermal expansion coefficients
  • stable at high temperatures
  • most efficient above 300°C
  • characterized by a high mechanical strength

Efficient TE-materials need:

  • high Seebeck-coeffizient S
  • high electrical conductivity σ 
  • low thermal conductivity  κ

Material Properties (typical values) @ room temperature

Alloy Seebeck-Coefficient
S [µV/K]
Electric Conductivity
σ  [S/cm]
Thermal Conductivity 
 κ  [W/(m·K)]

Density
ρ [g/cm3]

Heat Capacity
Cp [J/(g ·K)]
VACOTHERM n -145 3,500 5.5 7.4 0.31
VACOTHERM p 110 3,500 7.2 8.1 0.29

Today, thermoelectric power generation gains importance in the context of direct conversion of thermal energy into electrical energy. Applications are exhaust energy recovery in automotive or heavy duty vehicles, waste heat recovery in industry or improving efficiency in combined heat and power plants. The typical operating principle of a thermoelectric generator (TEG) is shown opposite. The main advantages of this direct energy conversion are that no mechanical or chemical processes and no moving parts, liquids or gases are needed. The devices are robust, compact and maintenance free.

The recently developed thermoelectric materials VACOTHERM are Hafnium (Hf-) free half-Heusler intermetallic compounds. There are two differently doped types of VACOTHERM®: VACOTHERM n and VACOTHERM p are our n-type and p-type semiconducting thermoelectric materials. Both intermetallic compounds match perfectly in terms of thermal expansion coefficients, are stable at high temperatures, most efficient above 300°C and are characterized by a high mechanical strength.    

The working mechanism of VACOTHERM materials - used in TEG - is based on the Seebeck-effect: when placed in a temperature gradient, the materials generate a useable electric voltage.

The ability of a thermoelectric material to convert heat into electricity is expressed by its figure of merit ZT. 


In order to realize high ZT-values, the combination of a high Seebeck coefficient S with high electric conductivity σ and low thermal conductivity κ is necessary. This unique set of properties could be realized in our VACOTHERM materials.

With ZT-values of 0,9 @ 500 °C VACOTHERM is tailored for optimum efficiency at higher temperatures, where conventional Bismuth-Telluride thermoelectric materials fail. This makes them ideal candidates for many waste heat recovery applications.

Typical material properties such as Seebeck-coefficient, electric conductivity and thermal conductivity of VACOTHERM n and VACOTHERM p are shown.

Forms of supply

Standard form of supply:                          small blocks typically 1-2 mm per dimension

Optional coating of contact surfaces:   nickel or gold available
                                                                      other coatings possible - on request 

Other shapes and formats:                      custom-tailored geometries possible - on request

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VACOTHERM

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