Over the years,the fact that the quaternary diamond-like thermoelectric materials show much lower carrier mobilities than ternary compounds remains mysterious.In this work,by adopting first-principles defect chemistry...Over the years,the fact that the quaternary diamond-like thermoelectric materials show much lower carrier mobilities than ternary compounds remains mysterious.In this work,by adopting first-principles defect chemistry and electrical transport calculations,the fundamental origin of the difference on carrier mobility between quaternary and ternary diamond-like compounds is addressed,exemplified by Cd_(2)Cu_(3)In_(3)Te_(8).The results of defect chemistry show that the main intrinsic defects in quaternary compound Cd_(2)Cu_(3)In_(3)Te_(8) are substitutional defects,i.e.,CdIn and CdCu,differing from the copper vacancy defect in ternary Cu-based compound such as CuInTe_(2).The low defect formation energies in Cd_(2)Cu_(3)In_(3)Te_(8) result in high defect concentrations,which is caused by the similar atomic radii and electronegativities between CdeIn and CdeCu.Further calculations show that the low-energy defects are mainly located around the valence band maximum in Cd_(2)Cu_(3)In_(3)Te_(8).The electrical transport calculations,considering both the acoustic phonon scattering and ionized impurity scattering,demonstrate that mainly due to the higher concentration of the ionized defects,the mobility of the quaternary Cd_(2)Cu_(3)In_(3)Te_(8) is much lower than that of ternary CuInTe2.Our work sheds light on the intrinsic defects in quaternary diamond-like compounds and their influence on charge transport.展开更多
Dimer impurity in the solution of a generation five(G5) polyamidoamine(PAMAM) dendrimer has been investigated by small-angle neutron scattering(SANS). The existence of dimer impurity in dendrimer solution was evidence...Dimer impurity in the solution of a generation five(G5) polyamidoamine(PAMAM) dendrimer has been investigated by small-angle neutron scattering(SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform(IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.展开更多
The magnetic impurity scattering plays an important role in the phase coherence behavior of thin films.By using the thickness and disorder dependences of the low temperature logarithmic anomaly in resistivity we are a...The magnetic impurity scattering plays an important role in the phase coherence behavior of thin films.By using the thickness and disorder dependences of the low temperature logarithmic anomaly in resistivity we are able to determine the concentration of magnetic impurities in Au films and demonstrate that the low temperature saturation or plateau in phase decoherence time is closely related with the Kondo effect.展开更多
Based on semiclassical Boltzamnn transport theory in random phase approximation, we develop a theoretical model to investigate low-temperature carrier transport properties in relatively high doped bilayer graphene. In...Based on semiclassical Boltzamnn transport theory in random phase approximation, we develop a theoretical model to investigate low-temperature carrier transport properties in relatively high doped bilayer graphene. In the presence of both electron–hole puddles and band gap induced by charged impurities, we calculate low-temperature charged impurity scattering-limited conductivity in relatively high doped bilayer graphene. Our calculated conductivity results are in excellent agreement with published experimental data in all compensated gate voltage regime of study by using potential fluctuation parameter as only one free fitting parameter, indicating that both electron–hole puddles and band gap induced by charged impurities play an important role in carrier transport. More importantly, we also find that the conductivity not only depends strongly on the total charged impurity density, but also on the top layer charged impurity density, which is different from that obtained by neglecting the opening of band gap, especially for bilayer graphene with high top layer charged impurity density.展开更多
We present a systematic study of the impurity scattering effect induced by Pd dopants in the super- conductor SrPt3P. Using a solid-state reaction method, we fabricated the Pd-doped superconductor Sr（Pt1-xPdx）3P. We...We present a systematic study of the impurity scattering effect induced by Pd dopants in the super- conductor SrPt3P. Using a solid-state reaction method, we fabricated the Pd-doped superconductor Sr（Pt1-xPdx）3P. We found that the residual resistivity P0 increases quickly with Pd doping, whereas the residual resistance ratio （RRR） displays a dramatic reduction. In addition, both the nonlinear field-dependent behavior of the Hall resistivity Pxy and the strong temperature dependence of the Hall coefficient RH at low temperature are suppressed by Pd doping. All the experimental results can be explained by an increase in scattering by impurities induced by doping. Our results suggest that the Pt position is very crucial to the carrier conduction in the present system.展开更多
基金supported by the National Key Research and Development Program of China(No.2018YFB0703600)Key Research Project of Zhejiang Laboratory(No.2021PE0AC02)+1 种基金the Natural Science Foundation of China(Grant Nos.52172216 and 92163212)the 111 Project D16002.
文摘Over the years,the fact that the quaternary diamond-like thermoelectric materials show much lower carrier mobilities than ternary compounds remains mysterious.In this work,by adopting first-principles defect chemistry and electrical transport calculations,the fundamental origin of the difference on carrier mobility between quaternary and ternary diamond-like compounds is addressed,exemplified by Cd_(2)Cu_(3)In_(3)Te_(8).The results of defect chemistry show that the main intrinsic defects in quaternary compound Cd_(2)Cu_(3)In_(3)Te_(8) are substitutional defects,i.e.,CdIn and CdCu,differing from the copper vacancy defect in ternary Cu-based compound such as CuInTe_(2).The low defect formation energies in Cd_(2)Cu_(3)In_(3)Te_(8) result in high defect concentrations,which is caused by the similar atomic radii and electronegativities between CdeIn and CdeCu.Further calculations show that the low-energy defects are mainly located around the valence band maximum in Cd_(2)Cu_(3)In_(3)Te_(8).The electrical transport calculations,considering both the acoustic phonon scattering and ionized impurity scattering,demonstrate that mainly due to the higher concentration of the ionized defects,the mobility of the quaternary Cd_(2)Cu_(3)In_(3)Te_(8) is much lower than that of ternary CuInTe2.Our work sheds light on the intrinsic defects in quaternary diamond-like compounds and their influence on charge transport.
基金financially supported by the National Natural Science Foundation of China (Nos. 11475267, 11005159, and 21725402)
文摘Dimer impurity in the solution of a generation five(G5) polyamidoamine(PAMAM) dendrimer has been investigated by small-angle neutron scattering(SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform(IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.
基金supported by the National Basic Research Program of China (Grant No. 2006CB91304)the Knowledge Innovation Project of Chinese Academy of Sciences
文摘The magnetic impurity scattering plays an important role in the phase coherence behavior of thin films.By using the thickness and disorder dependences of the low temperature logarithmic anomaly in resistivity we are able to determine the concentration of magnetic impurities in Au films and demonstrate that the low temperature saturation or plateau in phase decoherence time is closely related with the Kondo effect.
文摘Based on semiclassical Boltzamnn transport theory in random phase approximation, we develop a theoretical model to investigate low-temperature carrier transport properties in relatively high doped bilayer graphene. In the presence of both electron–hole puddles and band gap induced by charged impurities, we calculate low-temperature charged impurity scattering-limited conductivity in relatively high doped bilayer graphene. Our calculated conductivity results are in excellent agreement with published experimental data in all compensated gate voltage regime of study by using potential fluctuation parameter as only one free fitting parameter, indicating that both electron–hole puddles and band gap induced by charged impurities play an important role in carrier transport. More importantly, we also find that the conductivity not only depends strongly on the total charged impurity density, but also on the top layer charged impurity density, which is different from that obtained by neglecting the opening of band gap, especially for bilayer graphene with high top layer charged impurity density.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 11204338）, the ＂Strategic Priority Research Program （B）＂ of the Chinese Academy of Sciences （Grant No. XDB04040300）, and the Youth Innovation Promotion Association of the Chinese Academy of Sciences （Grant No. 2015187）. This work was partly sponsored by the Science and Technology Commission of Shanghai Municipality （Grant Nos. 14DZ2260700 and 14521102800）.
文摘We present a systematic study of the impurity scattering effect induced by Pd dopants in the super- conductor SrPt3P. Using a solid-state reaction method, we fabricated the Pd-doped superconductor Sr（Pt1-xPdx）3P. We found that the residual resistivity P0 increases quickly with Pd doping, whereas the residual resistance ratio （RRR） displays a dramatic reduction. In addition, both the nonlinear field-dependent behavior of the Hall resistivity Pxy and the strong temperature dependence of the Hall coefficient RH at low temperature are suppressed by Pd doping. All the experimental results can be explained by an increase in scattering by impurities induced by doping. Our results suggest that the Pt position is very crucial to the carrier conduction in the present system.
基金supported by the National Key R&D Program of China(2022YFA1203802 and 2021YFA1202903)the National Natural Science Foundation of China(92264202,61974060 and 61674080)the Innovation and Entrepreneurship Program of Jiangsu Province.
