Abstract. A novel measurement device for simultaneous high temperature measurements of the electrical conductivity and the Hall coefficient has been developed. Simulations were used to design a suitable screen-printed planar platinum heating structure that generates temperatures of up to 600 ∘C by Joule heating. Simulations of the temperature distribution have been validated using thermal imaging. With the hardware setup of two permanent magnetic yoke systems with a magnetic flux density of ±760 mT, the electrical conductivity and the charge carrier densities of a silicon wafer and a gold film were measured, as examples of a typical semiconductor with low charge carrier densities but high mobility and a metal representing materials with very high charge carrier densities but moderate mobilities, respectively. Measurements were compared with data from the literature to validate the functionality of the novel, low-cost measurement device.
The powder aerosol deposition (PAD) method is a spray‐coating process to form dense, nanocrystalline ceramic films at room temperature without thermal treatment. Herein, the thermoelectric properties of PAD‐deposited Bi2Te3 films are investigated. The powders are deposited on rigid Al2O3 substrates and on flexible polymer sheets (Kapton and Mylar) attached to Kanthal foils. A low thermal conductivity of λ = 0.12 W m−1 K−1, an electrical conductivity of σ = 29.8 S cm−1, and a Seebeck coefficient of S = –145 μV K−1 are determined on Al2O3. To evaluate the flexibility of the Bi2Te3 films deposited on flexible polymer sheets, the electrical conductivity and the Seebeck coefficient are measured before, during, and again after bending. While the Seebeck coefficient remains unaffected by the bending process and the bending radius, the electrical conductivity deteriorates to some extent during bending. Subsequent measurements in the nonbent planar state reveal, however, that the conductivity is restored partially. Furthermore, first, flexible thermoelectric generators could be prepared and characterized. PAD offers enormous potential not only in the combination of Bi2Te3 films on polymer sheets without thermal treatment, but also for manufacturing flexible thermoelectric generators in general.
Abstract. A new high temperature gauge to simultaneously determine
the electrical conductivity, the Hall constant, and the Seebeck coefficient
has been developed. Screen-printed heating structures on a ceramic sample
holder are used to generate temperatures up to 800 ∘C by Joule
heating. The heating structures were designed using the finite element method (FEM) simulations and the
temperature distribution was validated by thermal imaging. To measure the
Seebeck coefficient, Au/Pt thermocouples with different geometries were
investigated and successfully integrated into the gauge. Measurements on
constantan, a typical Seebeck coefficient reference material with high
electrical conductivity, high charge carrier concentration, and a known
Seebeck coefficient, as well as on a well-described boron-doped silicon
wafer confirm the functionality of the gauge up to 800 ∘C.
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