The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectr...The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectric performance in its stable,hexagonal phase.The challenge for higher figure of merit(zT) values lies in reducing the hole carrier concentration and enhancing the Seebeck coefficient,which,however,can be hardly realized by conventional doping.Here in this work,we report that the electrical properties of Ge2 Sb2 Te5 can be readily optimized by anion-site modulation.Specifically,Se/S substitution for Te induces stronger and more ionic bonding,lowering the hole density.Furthermore,an increase in electronic density of state is introduced by Se substitution,contributing to a large increase in Seebeck coefficient.Combined with the reduced thermal conductivity,maximum zT values above 0.7 at 800 K have been achieved in Se/S-alloyed materials,which is ~30% higher than that in the pristine Ge2Sb2 Te5.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2017YFA0700705 and 2018YFB0703600)the National Natural Science Foundation of China(Nos.51625205,91963208 and 51802333)Shanghai Sailing Program(No.18YF1426700)。
文摘The amalgamation of multi-subjects often elicits novel materials,new concepts and unexpected applications.Recently,Ge2 Sb2 Te5,as the most established phasechange material,has been found to exhibit decent thermoelectric performance in its stable,hexagonal phase.The challenge for higher figure of merit(zT) values lies in reducing the hole carrier concentration and enhancing the Seebeck coefficient,which,however,can be hardly realized by conventional doping.Here in this work,we report that the electrical properties of Ge2 Sb2 Te5 can be readily optimized by anion-site modulation.Specifically,Se/S substitution for Te induces stronger and more ionic bonding,lowering the hole density.Furthermore,an increase in electronic density of state is introduced by Se substitution,contributing to a large increase in Seebeck coefficient.Combined with the reduced thermal conductivity,maximum zT values above 0.7 at 800 K have been achieved in Se/S-alloyed materials,which is ~30% higher than that in the pristine Ge2Sb2 Te5.
基金supported by the National Key Basic Research Program of China(973)(2015CB251401)National Natural Science Foundation of China(21176205,21322602)+1 种基金Zhejiang Provincial Natural Science Foundation of China(LZ17B060001)Fundamental Research Funds of the Central Universities~~
