n-Type ZnO-based semiconducting materials are increasingly studied for thermoelectrics(TE)in the past due to their inexpensive and non-toxic nature coupled with their high Seebeck coefficient and stability at elevated...n-Type ZnO-based semiconducting materials are increasingly studied for thermoelectrics(TE)in the past due to their inexpensive and non-toxic nature coupled with their high Seebeck coefficient and stability at elevated temperatures.However,their high thermal conductivity limits their prospect for TE application.In this work,a novel,simpler and faster bottom-up approach to produce thermoelectric Al-doped ZnO ceramics from nanopowders produced by an interfacial reaction(double emulsion method)followed by consolidation by spark plasma sintering(SPS)is explored.This alternative interfacial reaction yielded porous aggregates composed of nanoparticles,which exhibited distinctly enhanced TE performance after densification by SPS at low pressure,due to the notable improvement in the power factor and pro-nounced suppression of the lattice thermal conductivity caused by the nano/micro-structure engineered by this bottom-up synthesis technique.This encompasses grain size reduction,inclusion of Al-rich nano-precipitates,and nanoporosity,thus enabling scattering of phonons of different mean free paths.A maximum figure of merit ZT∼0.13 at 750 K was obtained for Zn_(0.97)Al_(0.03)O ceramics,a substantial enhancement to the previously reported values for the same composition synthesized by the traditional synthesis methods.展开更多
基金supported by JSPS JP19H00833,JP19F19720,JP16H06441,JP17H02749,JST Mirai JPMJMI19A1,CREST JPMJCR19Q4.
文摘n-Type ZnO-based semiconducting materials are increasingly studied for thermoelectrics(TE)in the past due to their inexpensive and non-toxic nature coupled with their high Seebeck coefficient and stability at elevated temperatures.However,their high thermal conductivity limits their prospect for TE application.In this work,a novel,simpler and faster bottom-up approach to produce thermoelectric Al-doped ZnO ceramics from nanopowders produced by an interfacial reaction(double emulsion method)followed by consolidation by spark plasma sintering(SPS)is explored.This alternative interfacial reaction yielded porous aggregates composed of nanoparticles,which exhibited distinctly enhanced TE performance after densification by SPS at low pressure,due to the notable improvement in the power factor and pro-nounced suppression of the lattice thermal conductivity caused by the nano/micro-structure engineered by this bottom-up synthesis technique.This encompasses grain size reduction,inclusion of Al-rich nano-precipitates,and nanoporosity,thus enabling scattering of phonons of different mean free paths.A maximum figure of merit ZT∼0.13 at 750 K was obtained for Zn_(0.97)Al_(0.03)O ceramics,a substantial enhancement to the previously reported values for the same composition synthesized by the traditional synthesis methods.
