کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1332066 979029 2011 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Thermal and electronic charge transport in bulk nanostructured Zr0.25Hf0.75NiSn composites with full-Heusler inclusions
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Thermal and electronic charge transport in bulk nanostructured Zr0.25Hf0.75NiSn composites with full-Heusler inclusions
چکیده انگلیسی

Bulk Zr0.25Hf075NiSn half-Heusler (HH) nanocomposites containing various mole fractions of full-Heusler (FH) inclusions were prepared by solid state reaction of pre-synthesized HH alloy with elemental Ni at 1073 K. The microstructures of spark plasma sintered specimens of the HH/FH nanocomposites were investigated using transmission electron microscopy and their thermoelectric properties were measured from 300 K to 775 K. The formation of coherent FH inclusions into the HH matrix arises from solid-state Ni diffusion into vacant sites of the HH structure. HH(1–y)/FH(y) composites with mole fraction of FH inclusions below the percolation threshold, y∼0.2, show increased electrical conductivity, reduced Seebeck coefficient and increased total thermal conductivity arising from gradual increase in the carrier concentration for composites. A drastic reduction (∼55%) in κl was observed for the composite with y=0.6 and is attributed to enhanced phonon scattering due to mass fluctuations between FH and HH, and high density of HH/FH interfaces.

Large reduction in the lattice thermal conductivity of bulk nanostructured half-Heusler/full-Heusler (Zr0.25Hf075NiSn/ Zr0.25Hf075Ni2Sn) composites, obtained by solid-state diffusion at 1073 K of elemental Ni into vacant sites of the half-Heusler structure, arising from the formation of regions of spinodally decomposed HH and FH phases with a spatial composition modulation of ∼2 nm.Figure optionsDownload as PowerPoint slideHighlights
► Bulk composites from solid state transformation of half-Heusler matrix through Ni diffusion.
► Formation of coherent phase boundaries between half-Heusler matrix and full-Heusler inclusion.
► Alteration of thermal and electronic transports with increasing full-Heusler inclusion.
► Enhanced phonon scattering at half-Heusler/ full-Heusler phase boundaries.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 184, Issue 11, November 2011, Pages 2948–2960
نویسندگان
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