Low-temperature enhanced figure of merit of ThSi<sub>x</sub>P<sub>1-x</sub> and prospects for thermoelectric energy performance
Azmat Iqbal Bashir, Muhammad Irfan, Sikander Azam, Muhammad Bilal Ahmed Siddique
Abstract
Abstract Rare Earth metals and actinides-based materials gained immense attention of scientists and technologists owing to their fascinating fundamental and applied prospects. These are large density, neutron abundance, enhanced melting temperature and thermal stability which enhance their thermal performance. Herein, we report on the low temperature-enhanced thermoelectric performance of ThP through silicon substitution via ThSi x P 1-x (x = 0, 0.25, 0.5, 0.75, 1). For the density functional theory-based quantum computation analysis on the Si substitution-assisted properties of ThP, we utilize all-electron full-potential with linearized augmented plane wave. For the theoretical characterization of the compounds for the desired properties, we treat the exchange-correlation density functional within TB-mBJ approximation. The computed thermoelectric properties via Boltzmann theory as implemented in BoltzTrap computer code are Seebeck coefficient ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>S</mml:mi> </mml:math> ), electrical ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>σ</mml:mi> </mml:math> ) and thermal conductivity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>k</mml:mi> </mml:math> ), power factor (PF) ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> <mml:mi>σ</mml:mi> </mml:math> ), and figure of merit ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">ZT</mml:mi> </mml:math> ). The substitution of Si into ThP renders a considerable enhancement of thermoelectric and transport performance of the ThSi x P 1-x samples with enhanced <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">σ</mml:mi> <mml:mo>,</mml:mo> </mml:math> PF, and ZT of orders 3.0 × 10 20 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mfenced close=")" open="(" separators=""> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mo>.</mml:mo> <mml:mi>s</mml:mi> <mml:mo>.</mml:mo> <mml:mi mathvariant="normal">cm</mml:mi> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mo>,</mml:mo> </mml:math> 2.5 × 10 12 Wm −1 K −2 s −1 and 1.6 at 50 K, respectively. To our knowledge, this is the highest low-temperature thermal efficiency achieved for the metallic thorium silicides. As such, the reported results hold great promise for fundamental prospects and technological interest such as thermoelectricity and fertile materials as nuclear fuel for clean nuclear energy technology.