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<p>A systematic investigation pertaining to the low temperature (10–350&#xa0;K) thermoelectric properties of Ni substituted Bi<sub>1.8−<i>x</i></sub>Ni<sub><i>x</i></sub>Sb<sub>0.2</sub>Te<sub>3</sub> alloys (<i>x</i> = 0–0.08), it was synthesised employing solid state reaction method. X-ray diffraction studies verified the presence of phase pure rhombohedral structures. FESEM micrographs showed a morphological transition from hexagonal platelets to granular networks as the Ni content increased. Electrical transport measurements revealed a transition from n-type to p-type conduction for the sample <i>x</i> ≥ 0.06. This transition is attributed to the formation of acceptor defects, which increases the hole concentration as a majority charge carriers. The thermal conductivity decreased systematically from 1.7 to 1.0&#xa0;Wm<sup>−1</sup>&#xa0;K<sup>−1</sup> at 350&#xa0;K with substitution of Ni concentration, as a result of the increased phonon scattering due to the mass disorder and strain fields. The optimal composition (<i>x</i> = 0.04) unveiled a maximum <InlineEquation ID="IEq1"><EquationSource Format="TEX">\(PF\)</EquationSource></InlineEquation> and <InlineEquation ID="IEq2"><EquationSource Format="TEX">\(ZT\)</EquationSource></InlineEquation> of 335&#xa0;μW/mK<sup>2</sup> and 0.09 respectively at 350&#xa0;K, <InlineEquation ID="IEq3"><EquationSource Format="TEX">\(ZT\)</EquationSource></InlineEquation> has 125% increment over the pristine sample. These results validates that Ni doping effectively decouples thermal and electronic transport properties via controlled defect engineering. This controlled doping represents a viable strategy for advancing thermoelectric performance of Bi–Sb–Te system.</p>

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Defect-mediated n-type to p-type transition and enhanced thermoelectric performance in Bi1.8−xNixSb0.2Te3 alloys

  • 期刊论文

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  • 发表日期：

    2026年5月25日

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  • G. Poojitha,
  • P. Poornesh,
  • Ashok Rao,
  • C. L. Hung,
  • Y. K. Kuo,
  • Om Prakash,
  • Dhanya Sunil

摘要

A systematic investigation pertaining to the low temperature (10–350 K) thermoelectric properties of Ni substituted Bi1.8−xNixSb0.2Te3 alloys (x = 0–0.08), it was synthesised employing solid state reaction method. X-ray diffraction studies verified the presence of phase pure rhombohedral structures. FESEM micrographs showed a morphological transition from hexagonal platelets to granular networks as the Ni content increased. Electrical transport measurements revealed a transition from n-type to p-type conduction for the sample x ≥ 0.06. This transition is attributed to the formation of acceptor defects, which increases the hole concentration as a majority charge carriers. The thermal conductivity decreased systematically from 1.7 to 1.0 Wm−1 K−1 at 350 K with substitution of Ni concentration, as a result of the increased phonon scattering due to the mass disorder and strain fields. The optimal composition (x = 0.04) unveiled a maximum \(PF\) and \(ZT\) of 335 μW/mK2 and 0.09 respectively at 350 K, \(ZT\) has 125% increment over the pristine sample. These results validates that Ni doping effectively decouples thermal and electronic transport properties via controlled defect engineering. This controlled doping represents a viable strategy for advancing thermoelectric performance of Bi–Sb–Te system.