THERMOELECTRIC MATERIALS SCIENCE AND NANOTECHNOLOGY. PRACTICE AND THEORY

2019;
: pp. 30-40
1
Lviv Polytechnic National University
2
Lviv Polytechnic National University, Ukraine
3
Lviv Polytechnic National University
4
Lviv Polytechnic National University
5
Technical University of Ilmenau, Germany

Progress  in  the  field  of  thermoelectricity  requires  the  further  development  of material  science  deep  into  the substance  through  the  use  of  the  achievements  of  applied  and  theoretical  advances  in  nanotechnologies,  including nanothermodynamics. This enables to expand the range of current thermodynamic forces, taking into account the forces inherent in nanostructured  substances,  and  to  increase  the  efficiency  of  attracting  the  concept  of  eddy  thermoelectric  currents  in  order  to increase the accuracy of temperature measurement by thermoelectric sensors. The researches of materials of thermoelectric sensors have  not  only  included  not  only  the  study  of  the  stability  of  thermoelectric  sensors,  but  their  study  by  their methods  of  non-destructive acoustic control. This makes it possible to assess and develop the role of specific mechanisms for the formation of eddy thermoelectric currents in the drift of thermoelectric power.

According  to  the results of acoustic studies of  thermometric materials of  thermoelectric sensors, the possibilities of  their characterization were  revealed  in  a non-destructive way. The  influence of micro  and nanostructural effects on  the  formation of local eddy thermoelectric currents as the source of thermoelectric power is evaluated. Taking into account thermodynamic forces and  flows  inherent  in  nanostructured  thermoelectric  materials,  it  becomes  possible  to  modify  the  concept  of  local  eddy thermoelectric  currents  concerning  the  enhancement  of  the  accuracy  of  temperature measurement. The mechanism  of  currents formation due  to  the  effect  of  coherence  in nanostructured materials  is  studied. Here minimal  temperature  changes  lead  to  the appearance of currents. On the other hand, the similar mechanism caused by the gradient of mechanical stresses raises. The latter permits  the modification  of  thermoelectric materials  by  forming multidimensional  fields  of  elastic micro  stresses  that  can  be especially effective for nanostructured thermoelectric materials.

Eddy  thermoelectric  currents,  for which  a  temperature gradient  is  required,  can be  considered  a partial  case of  a much broader class of eddy electrical currents occurring  in an electrically conducting substance under  the  influence of  fluctuations  in thermodynamic  parameters. The  stability  of  thermoelectric  power,  as well  as  its magnitude,  can  be  substantially  enhanced  in nanostructured  materials  by  the  direct  formation  of  gradients  of  thermodynamic  parameters,  different  from  the  temperature gradient.

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