Heusler alloys are a remarkable class of materials due to their mechanical robustness, low toxicity, outstanding thermoelectric performance, and excellent optoelectronic properties. This study presents a comprehensive theoretical investigation of novel d0 half-Heusler compounds, LiSrZ (Z = Sb, Bi), using GGA-PBE and mBJ-GGA approximations. The results indicate that both alloys are p-type semiconductors with band gaps ranging from 0.712 to 1.928 eV. Analysis of the elastic constants confirms their mechanical stability, anisotropic nature, and brittle character. Optically, LiSrZ alloys are transparent in the near-infrared region, while exhibiting broad absorption and reflectivity spectra in the visible and ultraviolet (UV) ranges. More specifically, LiSrSb has a higher peak absorption coefficient of approximately <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$138\times {10}^{4}{\text{cm}}^{-1}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>138</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mn>4</mn> </msup> <msup> <mrow> <mtext>cm</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> and a maximum reflectivity of 62%, demonstrating its strong optical performance in the UV range. Furthermore, at 300 K, the electrical conductivity increases from <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$4.876\times {10}^{17}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>4.876</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mn>17</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> to <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$6.487\times {10}^{18}{(\Omega .\text{m}.\text{s})}^{-1}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>6.487</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mn>18</mn> </msup> <msup> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="normal">Ω</mi> <mo>.</mo> <mtext>m</mtext> <mo>.</mo> <mtext>s</mtext> <mo stretchy="false">)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> when substituting Sb with Bi, resulting in a slight improvement in the thermoelectric figure of merit (ZT) from 0.82 to 0.83. These findings highlight the potential of LiSrZ alloys for applications in optoelectronics and sustainable energy technologies, encouraging further experimental validation.

Optical and thermoelectric performances of LiSrZ (Z = Sb, Bi) for energy conversion applications: DFT and Boltzmann transport theory

期刊论文
发表日期：

2025年9月21日

查看全文

Aya Righi,
Fatima Bendahma,
Sabria Terkhi,
Mohamed Mana,
Abbes Labdelli,
Fatiha Bessaha,
Rabah Khenata,
Khedidja Mechehoud,
Bilel Achir

摘要

Heusler alloys are a remarkable class of materials due to their mechanical robustness, low toxicity, outstanding thermoelectric performance, and excellent optoelectronic properties. This study presents a comprehensive theoretical investigation of novel d⁰ half-Heusler compounds, LiSrZ (Z = Sb, Bi), using GGA-PBE and mBJ-GGA approximations. The results indicate that both alloys are p-type semiconductors with band gaps ranging from 0.712 to 1.928 eV. Analysis of the elastic constants confirms their mechanical stability, anisotropic nature, and brittle character. Optically, LiSrZ alloys are transparent in the near-infrared region, while exhibiting broad absorption and reflectivity spectra in the visible and ultraviolet (UV) ranges. More specifically, LiSrSb has a higher peak absorption coefficient of approximately $138\times {10}^{4}{\text{cm}}^{-1}$ $138 \times 10^{4} {cm}^{- 1}$ and a maximum reflectivity of 62%, demonstrating its strong optical performance in the UV range. Furthermore, at 300 K, the electrical conductivity increases from $4.876\times {10}^{17}$ $4.876 \times 10^{17}$ to $6.487\times {10}^{18}{(\Omega .\text{m}.\text{s})}^{-1}$ $6.487 \times 10^{18} {(Ω . m . s)}^{- 1}$ when substituting Sb with Bi, resulting in a slight improvement in the thermoelectric figure of merit (ZT) from 0.82 to 0.83. These findings highlight the potential of LiSrZ alloys for applications in optoelectronics and sustainable energy technologies, encouraging further experimental validation.