Anisotropy and inhomogeneity are ubiquitous in spark plasma sintered thermoelectric devices.However,the origin of inhomogeneity in thermoelectric nanocomposites has rarely been investigated so far.Herein,we systematic...Anisotropy and inhomogeneity are ubiquitous in spark plasma sintered thermoelectric devices.However,the origin of inhomogeneity in thermoelectric nanocomposites has rarely been investigated so far.Herein,we systematically study the impact of inhomogeneity in spark plasma sintered bismuth antimony telluride(BiSbTe)thermoelectric nanocomposites fabricated from solution-synthesized nanoplates.The figure of merit can reach 1.18,which,however,can be overestimated to 1.88 without considering the inhomogeneity.Our study reveals that the inhomogeneity in thermoelectric properties is attributed to the non-uniformity of porosity,textures and elemental distribution from electron backscatter diffraction and energy-dispersive spectroscopy characterizations.This finding suggests that the optimization of bulk material homogeneity should also be actively pursued in any future thermoelectric material research.展开更多
We report the investigation of the thermoelectric properties of large-scale solution-synthesized Bi2Te3 nanocomposites prepared from nanowires hot- pressed into bulk pellets. A third element, Se, is introduced to tune...We report the investigation of the thermoelectric properties of large-scale solution-synthesized Bi2Te3 nanocomposites prepared from nanowires hot- pressed into bulk pellets. A third element, Se, is introduced to tune the carrier concentration of the nanocomposites. Due to the Se doping, the thermoelectric figure of merit （ZT） of the nanocomposites is significantly enhanced due to the increased power factor and reduced thermal conductivity. We also find that thermal transport in our hot-pressed pellets is anisotropic, which results in different thermal conductivities along the in-plane and cross-plane directions. Theoretical calculations for both electronic and thermal transport are carried out to establish fundamental understanding of the material system and provide directions for further ZT optimization with adjustments to carrier concentration and mobility.展开更多
基金R.K.C.acknowledges grant#NSF(DMR-1508420).Y.W.thanks the support from the Herbert L.Stiles Professorship and ACRI Center IrHtiative from Iowa State University.
文摘Anisotropy and inhomogeneity are ubiquitous in spark plasma sintered thermoelectric devices.However,the origin of inhomogeneity in thermoelectric nanocomposites has rarely been investigated so far.Herein,we systematically study the impact of inhomogeneity in spark plasma sintered bismuth antimony telluride(BiSbTe)thermoelectric nanocomposites fabricated from solution-synthesized nanoplates.The figure of merit can reach 1.18,which,however,can be overestimated to 1.88 without considering the inhomogeneity.Our study reveals that the inhomogeneity in thermoelectric properties is attributed to the non-uniformity of porosity,textures and elemental distribution from electron backscatter diffraction and energy-dispersive spectroscopy characterizations.This finding suggests that the optimization of bulk material homogeneity should also be actively pursued in any future thermoelectric material research.
基金H. Y. F. thanks Scott Finefrock and Tianyue Gao for the help in Hall measurement. H. Y. F. and Y. W. acknowledge the use of the hot press setup in Prof. Chin-The Sun＇s lab at Purdue University. H. Y. F. and Y. W. acknowledge Air Force Office of Scientific Research （No. FA9550-12-1-0061）. T. L. F. and X. L. R. acknowledge the partial support from National Science Foundation （No. 1150948）.
文摘We report the investigation of the thermoelectric properties of large-scale solution-synthesized Bi2Te3 nanocomposites prepared from nanowires hot- pressed into bulk pellets. A third element, Se, is introduced to tune the carrier concentration of the nanocomposites. Due to the Se doping, the thermoelectric figure of merit （ZT） of the nanocomposites is significantly enhanced due to the increased power factor and reduced thermal conductivity. We also find that thermal transport in our hot-pressed pellets is anisotropic, which results in different thermal conductivities along the in-plane and cross-plane directions. Theoretical calculations for both electronic and thermal transport are carried out to establish fundamental understanding of the material system and provide directions for further ZT optimization with adjustments to carrier concentration and mobility.
