Browsing by Author "Deng, Ping-Yuan"

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From Dislocation to Nano-Precipitation: Evolution to Low Thermal Conductivity and High Thermoelectric Performance inn-Type PbTe
(1970-01-01)
Deng, Ping-Yuan
;
Wang, Kuang-Kuo
;
Du, Jia-Yu
;
Wu, Hsin-Jay
;
材料科學與工程學系
PbTe-based alloys have been widely used as mid-temperature thermoelectric (TE) materials since the 1960s. Years of endeavor spurred the tremendous advances in their TE performance. The breakthroughs forn-type PbTe have been somewhat less impressive, which limits the overall conversion efficiency of a PbTe-based TE device. In light of this obstacle, ann-type Ga-doped PbTe via an alternative thermodynamic route that relies on the equilibrium phase diagram and microstructural evolution is revisited. Herein, a plateau ofzT= 1.2 is achieved in the best-performing Ga0.02Pb0.98Te in the temperature range of 550-673 K. Notably, an extremely high averagezT(ave)= 1.01 is obtained within 300 - 673 K. The addition of gallium optimizes the carrier concentration and boosts the power factorPF = S-2 rho(-1). Meanwhile, the kappa(L)of Ga-PbTe reveals a significantly decreasing tendency owing to the defect evolution that changes from dislocation loop to nano-precipitation with increasing Ga content. The pathway for both the kappa(L)reduction and defect evolution can be probed by an equilibrium phase diagram, which opens up a new avenue for locating highzTTE materials.
Titanium-based thin film metallic glass as diffusion barrier layer for PbTe-based thermoelectric modules
(2019-01-01)
Yu, Chia-Chi
;
Wu, Hsin-Jay
;
Agne, Matthias T.
;
Witting, Ian T.
;
Deng, Ping-Yuan
The thin film metallic glass (TFMG) is an effective diffusion barrier layer for PbTe-based thermoelectric (TE) modules. Reaction couples structured with Cu/TFMG/PbTe are prepared via sputter-deposition and are annealed at 673 K for 8-96 h. The transmission line method is adopted for the assessment of electrical contact resistivity upon the PbTe/TFMG, and the value remains in the range of 3.3-2.5 x 10(-9) (Omega m(2)). The titanium-based TFMG remains amorphous upon annealing at 673 K for 48 h and effectively blocks the inter-diffusion by not having grain-boundaries, which only allows the bulk diffusion between the metal electrode and the TE substrate. (C) 2019 Author(s).