Glass-like electronic and thermal transport in crystalline cubic germanium selenide

Thermoelectric properties of orthorhombic or rhombohedral GeSe have attracted great attention recently,with the rise of its structural analog Sn Se.However,the p-type cubic GeSe with higher symmetry and higher valence band degeneracy,which might exhibit higher thermoelectric performance,has never been synthesized.Here we report on the successful synthesis of p-type crystalline cubic GeSe by alloying with Sb2Te3 and the spontaneously formed Ge-vacancies.An unexpected glass-like temperature independent lattice thermal conductivity is observed in crystalline cubic GeSe,which results from strong phonon scattering by vacancy-induced disorders.Combining the multiple scattering theory and chemical bond analysis,we further reveal the existence of Anderson localization induced by Ge-vacancies.The Anderson localization results in a nearly constant Seebeck coefficient with increasing the carrier concentration.These results provide a general insight towards understanding and improving the thermoelectric properties of thermoelectric materials with vacancies and atomic-scale disorders.

Achieving Reliable CoSb_(3) based thermoelectric joints with low contact resistivity using a high-entropy alloy diffusion barrier layer

Skutterudite(SKD)thermoelectric materials have high conversion efficiency,great mechanical proper-ties,and economical practicability in the medium temperature range(500e550C).They need to bejoined with metal electrodes to form a thermoelectric power generation device during application.However,high contact resistivity,severe element diffusion,and large coefficient of thermal expansionmismatch are main obstacles for their applications.To address these issues,a FeCoNiCrMo high-entropyalloy diffusion barrier layer was designed and prepared using an arc smelting method in this paper.Effectof heating temperatures on the microstructure and properties of the bonded joints were investigated.The maximum shear strength was 21.6 Mpa and the corresponding reaction layer thickness,contactresistivity were 3.77 mm,1.8 mUcm2 respectively at 600C,40 MPa,10 min.Shear strength dropped downto 18.8 MPa and the contact resistivity increased to 4.2 mU cm2 after aging for 640 h.Numerical modelwas established and it predicted that the contact resistivity would keep lower than 6.5 mU cm2(300 h,100 days)and 11 mU cm2(8760 h,1 year)and the reaction layer thickness would not exceed 25 mm(2400 h,100 days)and 45 mm(8760 h,1 year).