<br>新型混合金属碲化物Mn1.8(1)In0.8(1)Si2Te6的低导热率,Dalton Transactions

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新型混合金属碲化物Mn1.8(1)In0.8(1)Si2Te6的低导热率
Dalton Transactions ( IF 3.5 ) Pub Date : 2024-03-18 , DOI: 10.1039/d3dt03900e
Omair Shahid ₁ , Sweta Yadav ₁ , Kaustuv Manna ₂ , Gohil S Thakur _{3,

4,

5} , Jai Prakash ₁

Affiliation

具有固有超低导热系数的新型复杂混合金属碲化物（含有低毒性阳离子）的设计在热电领域至关重要。在此，我们报道了新型混合金属四元碲化物Mn _1.8(1) In _0.8(1) Si ₂ Te ₆的多晶和单晶的合成和表征。利用单晶 X 射线衍射和 EDX 研究确定了该相在室温下的结构和化学式。三角中心对称（空间群： P

1 m ) 标题相结构的晶胞常数为a = b = 7.0483(7) Å 和c = 7.1277(8) Å。该结构具有三个独立的阳离子位点，一个混合（In1/Mn1）、一个部分填充的Mn2和一个与Te1原子键合的Si1。结构中的每个金属原子（In和Mn）与六个相邻的Te1原子以八面体配位。该结构还具有 Si 原子二聚体的特征，每个 Si 原子与三个 Te1 原子键合，形成类似乙烷的 Si ₂ Te ₆单元。多晶Mn _1.8 In _0.8 Si ₂ Te ₆样品的光学吸收研究显示出0.6(2) eV的窄光学带隙。温度相关电阻率和塞贝克系数研究证实了具有高S值（301 μV K ^-1至444 μV K ^-1 ）的样品的p型半导体性质。多晶样品的总热导率 ( k _tot ) 研究显示加热时呈下降趋势，在 773 K 时具有极低的值 0.28 W m ^-1 K ^-1 。磁性测量表明样品在低于 8 K 时呈现玻璃状磁性行为。

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Low thermal conductivity in a new mixed metal telluride Mn1.8(1)In0.8(1)Si2Te6

The design of new complex mixed metal tellurides (containing low toxicity cations) with intrinsic ultralow thermal conductivity is of paramount importance in the field of thermoelectrics. Herein, we report the synthesis and characterization of polycrystalline and single crystals of a new mixed-metal quaternary telluride Mn_1.8(1)In_0.8(1)Si₂Te₆. The structural aspects and chemical formula of this phase at room temperature have been established using single crystal X-ray diffraction and EDX studies. The trigonal centrosymmetric (space group: P [3 with combining macron]

1m) structure of the title phase has cell constants of a = b = 7.0483(7) Å and c = 7.1277(8) Å. The structure has three independent cationic sites, one mixed (In1/Mn1), one partially filled Mn2, and one Si1, which are bonded with Te1 atoms. Each metal atom (In and Mn) in the structure is octahedrally coordinated with six neighboring Te1 atoms. The structure also features dimers of Si atoms, and each Si atom is bonded to three Te1 atoms to form ethane-like Si₂Te₆ units. The optical absorption study of a polycrystalline Mn_1.8In_0.8Si₂Te₆ sample shows a narrow optical bandgap of 0.6(2) eV. Temperature-dependent resistivity and Seebeck coefficient studies confirmed the p-type semiconducting nature of the sample with high values of S (301 μV K⁻¹ to 444 μV K⁻¹). The total thermal conductivity (k_tot) study of the polycrystalline sample shows a decreasing trend on heating with an extremely low value of 0.28 W m⁻¹ K⁻¹ at 773 K. Magnetic measurements indicate a glassy magnetic behavior for the sample below 8 K.

更新日期：2024-03-19

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