Abstract
We have investigated the crystal structure and high temperature thermoelectric properties of polycrystalline Bi2–2xNa2xSr2Co2−xWxOy (0 ≤ x ≤ 0.075)
samples. Powder x-ray diffraction data show that all samples are phase
pure consisting of misfit-layered structure of alternately stacked
hexagonal CoO2 and double rock-salt BiSrO2 layers. It is found that dual doping of Na and W in Bi2Sr2Co2Oy
system is fairly effective in improving the thermoelectric properties
owing to simultaneous decrease of electrical resistivity (ρ) and thermal conductivity (κ) of samples. All samples exhibit a large Seebeck coefficient (S), which seems not to be affected by the level of doping. As a result, a very high power factor (PF) of 2.82 × 10−4 W/m K2 has been obtained for x = 0.025 sample at 1000 K. The corresponding dimensionless figure of merit (zT) for this sample has been determined to be 0.35 at 1000 K, which is ∼ 2.2 times higher than zT value of the pristine sample providing a promising class of material for high-temperature thermoelectric applications.
Original language | English |
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Journal | Journal of Electronic Materials |
Volume | 48 |
Issue number | 7 |
Pages (from-to) | 4618-4626 |
ISSN | 0361-5235 |
DOIs | |
Publication status | Published - 2019 |
Keywords
- Bi2Sr2Co2O y
- Layered cobaltites
- Thermoelectric properties
- Power factor
- Figure of merit