In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of t...In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of the high Tc superconductors Gd1Ba2Cu3O7−δ phase with Sr substitution has been synthesized, i.e. Gd1(Ba2−xSrx)Cu3O7−δ compound. The sample was synthesized by using a solid-state reaction method with a wet mixing, sintered for 12 hours at temperature 900°C. The synthesis results are characterized by using XRD. The results of Match-3 software analysis showed high (higher 85%) Gd1Ba2Cu3O7−δ phase was formed. The Sr substitution causes changes to the structure, i.e. the lattice parameters a, b and c, where the orthorhombicity tends to decrease with increasing Sr content. Refinement results show that based on the oxygen occupancy, the total oxygen content tends to increase.展开更多
In this work,we show significantly enhanced thermoelectric performance in Cu_(2) SnSe_(3) via a synergistic effect of Cd-doping and CuGaTe_(2) alloying in the temperature range of 300-823 K.Both the electron and phono...In this work,we show significantly enhanced thermoelectric performance in Cu_(2) SnSe_(3) via a synergistic effect of Cd-doping and CuGaTe_(2) alloying in the temperature range of 300-823 K.Both the electron and phonon transport properties can be simultaneously regulated by Cd doping at Sn site,leading to a higher quality factor.Meanwhile,a maximum figure of merit(zT) value of ~0.68 was obtained for Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) sample at823 K,which is about four times higher than that of the pristine sample(zT=0.18 at 773 K).Furthermore,Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) was alloyed with CuGaTe_(2) to reduce the lattice thermal conductivity in the high-temperature region.Consequently,a further enhanced zT value(0.77,823 K) was achieved in the(Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3))_(0.94)(CuGaTe_(2))_(0.06) sample,with a high average zT(zT_(ave)) value of0.30 between 300 and 823 K.These results demonstrate that Cd-doping combined with CuGaTe2 alloying could be an effective method to enhance zT values of Cu_(2) SnSe_(3) based compounds.展开更多
The quaternary diamond-like compounds,A_(2)Cu_(3)In_(3)Te_(8)(A=Cd,Zn,Mn,Mg),are a new class of thermoelectric materials recently proposed by complex structure design.Among them,the Zn_(2)Cu_(3)In_(3)Te_(8) compound p...The quaternary diamond-like compounds,A_(2)Cu_(3)In_(3)Te_(8)(A=Cd,Zn,Mn,Mg),are a new class of thermoelectric materials recently proposed by complex structure design.Among them,the Zn_(2)Cu_(3)In_(3)Te_(8) compound possesses reasonable electrical transport properties but relatively high lattice thermal conductivity.Herein,the effects of Ag substitution on the phase stability and thermoelectric properties of Zn_(2)Cu_(3)In_(3)Te_(8) compound are reported.It is revealed that only the In sites show an appreciable tolerance for Ag doping.Ag substitution at the In sites introduces extra holes and thus results in improved electrical transport properties.Furthermore,the introducing of Ag lowers the sound velocities and enhances the phonon scattering of the Zn_(2)Cu_(3)In_(3)Te_(8) compound,which leads to a substantially reduction in lattice thermal conductivity.Finally,in virtue of the optimization in both electrical and thermal transport properties,the maximal zT value of Zn_(2)Cu_(3)In_(2.8)Ag_(0.2)Te_(8) sample reaches 0.62 at 823 K,which is 43%higher than the pristine sample.展开更多
基金This report is part of the fundamental research report with contract No.486 127/UN14.2/PNL.01.03.00/2016.
文摘In an effort to improve the performance of superconductors in the field and high temperatures it is important to study the superconducting mechanism. For this reason, the cation substitution can be conducted. One of the high Tc superconductors Gd1Ba2Cu3O7−δ phase with Sr substitution has been synthesized, i.e. Gd1(Ba2−xSrx)Cu3O7−δ compound. The sample was synthesized by using a solid-state reaction method with a wet mixing, sintered for 12 hours at temperature 900°C. The synthesis results are characterized by using XRD. The results of Match-3 software analysis showed high (higher 85%) Gd1Ba2Cu3O7−δ phase was formed. The Sr substitution causes changes to the structure, i.e. the lattice parameters a, b and c, where the orthorhombicity tends to decrease with increasing Sr content. Refinement results show that based on the oxygen occupancy, the total oxygen content tends to increase.
基金financially supported by the National Natural Science Foundation of China (Nos.11874356, 52071041,12004060,51972102 and 51877023)the Key Research Program of Frontier Sciences,CAS (No.QYZDB-SSW-SLH016)。
文摘In this work,we show significantly enhanced thermoelectric performance in Cu_(2) SnSe_(3) via a synergistic effect of Cd-doping and CuGaTe_(2) alloying in the temperature range of 300-823 K.Both the electron and phonon transport properties can be simultaneously regulated by Cd doping at Sn site,leading to a higher quality factor.Meanwhile,a maximum figure of merit(zT) value of ~0.68 was obtained for Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) sample at823 K,which is about four times higher than that of the pristine sample(zT=0.18 at 773 K).Furthermore,Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) was alloyed with CuGaTe_(2) to reduce the lattice thermal conductivity in the high-temperature region.Consequently,a further enhanced zT value(0.77,823 K) was achieved in the(Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3))_(0.94)(CuGaTe_(2))_(0.06) sample,with a high average zT(zT_(ave)) value of0.30 between 300 and 823 K.These results demonstrate that Cd-doping combined with CuGaTe2 alloying could be an effective method to enhance zT values of Cu_(2) SnSe_(3) based compounds.
基金This work was supported by the National Key Research and Development Program of China(grant nos.2018YFB0703600 and 2018YFA0702100)the National Natural Science Foundation of China(grant nos.51472241,51772186,51632005,and 51371194)the Science and Technology Commission of Shanghai Municipality(grant no.16DZ2260601).
文摘The quaternary diamond-like compounds,A_(2)Cu_(3)In_(3)Te_(8)(A=Cd,Zn,Mn,Mg),are a new class of thermoelectric materials recently proposed by complex structure design.Among them,the Zn_(2)Cu_(3)In_(3)Te_(8) compound possesses reasonable electrical transport properties but relatively high lattice thermal conductivity.Herein,the effects of Ag substitution on the phase stability and thermoelectric properties of Zn_(2)Cu_(3)In_(3)Te_(8) compound are reported.It is revealed that only the In sites show an appreciable tolerance for Ag doping.Ag substitution at the In sites introduces extra holes and thus results in improved electrical transport properties.Furthermore,the introducing of Ag lowers the sound velocities and enhances the phonon scattering of the Zn_(2)Cu_(3)In_(3)Te_(8) compound,which leads to a substantially reduction in lattice thermal conductivity.Finally,in virtue of the optimization in both electrical and thermal transport properties,the maximal zT value of Zn_(2)Cu_(3)In_(2.8)Ag_(0.2)Te_(8) sample reaches 0.62 at 823 K,which is 43%higher than the pristine sample.
