The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys(TAGS-x)have been demonstrated as a promising p-type candidate for thermoelectric applications,attracting numerous atten-tions on the advancements of thermoelectric performance.M...The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys(TAGS-x)have been demonstrated as a promising p-type candidate for thermoelectric applications,attracting numerous atten-tions on the advancements of thermoelectric performance.Manipulation of carrier concentration for optimizing ther-moelectric performance in TAGS can be achieved by varying the ratio of Ag to Sb,and the Ag/Sb ratio of~2/3 has been proven as the optimal composition.Therefore,this work focuses on the systematic investigation on ther-moelectric properties of(GeTe)_(1-x)[(Ag_(2)Te)_(0.4)(Sb_(2)Te_(3))_(0.6)]_(x) alloys.The crystal structure for the alloys transfers from rhombohedral to cubic at room temperature as x≥0.2.The evolution of band parameter is estimated using a single parabolic band(SPB)model with acoustic phonon scat-tering.The density of states effective mass increases with x increasing,which leads to an enhancement of Seebeck coefficient along with a reduction in Hall mobility due to the additional carrier scattering by point defects.Mean-while,the lattice thermal conductivity of lower than~0.7 W·m^(-1)·K^(-1) in the entire temperature range and the lowest one of only 0.45 W·m^(-1)·K^(-1) is achieved due to additional phonon scattering by point defects.As a result,a peak thermoelectric figure of merit(zT)of~1.80 and an average one of~1.37 in 300–800 K are realized in non-stoichiometric TAGS alloys here.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51861145305 and 52022068)the Fundamental Research Funds for Science and Technology Innovation Plan of Shanghai (No. 18JC1414600)+1 种基金Hefei National Laboratory for Physical Sciences at the Microscale (No. KF2020007)Shanghai Natural Science Foundation (No. 19ZR1459900)。
文摘The(GeTe)_(x)(AgSbTe_(2))_(100-x)alloys(TAGS-x)have been demonstrated as a promising p-type candidate for thermoelectric applications,attracting numerous atten-tions on the advancements of thermoelectric performance.Manipulation of carrier concentration for optimizing ther-moelectric performance in TAGS can be achieved by varying the ratio of Ag to Sb,and the Ag/Sb ratio of~2/3 has been proven as the optimal composition.Therefore,this work focuses on the systematic investigation on ther-moelectric properties of(GeTe)_(1-x)[(Ag_(2)Te)_(0.4)(Sb_(2)Te_(3))_(0.6)]_(x) alloys.The crystal structure for the alloys transfers from rhombohedral to cubic at room temperature as x≥0.2.The evolution of band parameter is estimated using a single parabolic band(SPB)model with acoustic phonon scat-tering.The density of states effective mass increases with x increasing,which leads to an enhancement of Seebeck coefficient along with a reduction in Hall mobility due to the additional carrier scattering by point defects.Mean-while,the lattice thermal conductivity of lower than~0.7 W·m^(-1)·K^(-1) in the entire temperature range and the lowest one of only 0.45 W·m^(-1)·K^(-1) is achieved due to additional phonon scattering by point defects.As a result,a peak thermoelectric figure of merit(zT)of~1.80 and an average one of~1.37 in 300–800 K are realized in non-stoichiometric TAGS alloys here.
