The iron-based nontoxic chalcogenide superconductor Fe(Te,Se)has great potential for high magnetic field applications while it lacks a reliable method to produce bulk superconductor so far.Here we report a one-step sy...The iron-based nontoxic chalcogenide superconductor Fe(Te,Se)has great potential for high magnetic field applications while it lacks a reliable method to produce bulk superconductor so far.Here we report a one-step synthesis method to grow high-quality Fe(Te,Se)single crystals free of interstitial iron atoms through minor Mn doping.Bulk superconductivity is revealed in the as-grown centimetersized crystals with the optimal doping level of 1% Fe atoms substituted by Mn,which is systematically demonstrated by sharp electrical resistivity and magnetic susceptibility transitions,and large specific heat jumps.Compared with the undoped sample,the optimally doped one shows a significantly enhanced upper critical field,and a large self-field critical current density J_(c) of 4.5×10^(5)A cm^(-2) at 2 K(calculated by the Bean model),which maintains large values under high fields.The absence of interstitial iron atoms is testified by the scanning tunneling microscopy,and the effect of Mn doping is discussed.Our results provide a practical method by minor Mn doping to directly synthesize high-performance Fe(Te,Se)bulks that allow for future high-field superconducting applications.展开更多
Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-b...Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.展开更多
We have synthesized polycrystalline samples of Fe1.11(Te1-xSx) and single crystals of Fe1+y(Te0.88S0.12),and characterized their properties.Our results show that the solid solution of S in the Fe1.11Te tetragonal latt...We have synthesized polycrystalline samples of Fe1.11(Te1-xSx) and single crystals of Fe1+y(Te0.88S0.12),and characterized their properties.Our results show that the solid solution of S in the Fe1.11Te tetragonal lattice is limited,~10%.We observed superconductivity at ~8 K in both polycrystalline samples and single crystals.Magnetization measurements reveal that the volume fraction is small for this superconducting phase in both polycrystalline samples as-synthesized and single crystals as-grown.It is found that annealing in air enhances the superconducting fraction;the maximum fraction is almost 100% in the single crystals annealed in air at 300°C.We discuss the effect of annealing on superconductivity and transport properties at the normal state in the Fe1+y(Te1-xSx) system in terms of decrease of the excess Fe.展开更多
开展6 000和10 000 k N·m能级强夯的现场试验,以强夯前后多道瞬态面波测试和重型动力触探试验方法,对强夯处理效果进行测试。试验结果表明:强夯加固处理后地基承载力和土体工程特性得到改善,但地基承载力特征值和压缩模量局部深度...开展6 000和10 000 k N·m能级强夯的现场试验,以强夯前后多道瞬态面波测试和重型动力触探试验方法,对强夯处理效果进行测试。试验结果表明:强夯加固处理后地基承载力和土体工程特性得到改善,但地基承载力特征值和压缩模量局部深度仍不能满足设计要求;6 000和10 000 k N·m能级有效加固深度分别为6.0~7.0 m和7.0~8.0 m;10 000 k N·m能级试验区浅层加固处理效果较差,与浅层存在淤泥质土、夯坑回填方式及第3遍夯点间距过大和夯能过小等因素有关,需采取相应的处理措施。展开更多
Thermoelectric layers as Bi<sub>2</sub>Te<sub>3</sub>, Yb<sub>0.19</sub>Co<sub>4</sub>Sb<sub>12</sub>, FeSb<sub>2</sub>Te, Ce<sub>0.1</s...Thermoelectric layers as Bi<sub>2</sub>Te<sub>3</sub>, Yb<sub>0.19</sub>Co<sub>4</sub>Sb<sub>12</sub>, FeSb<sub>2</sub>Te, Ce<sub>0.1</sub>Fe<sub>0.7</sub>Co<sub>3.3</sub>Sb<sub>12</sub> and FeSb<sub>2</sub>Te/Ce<sub>0.1</sub>Fe<sub>0.7</sub>Co<sub>3.3</sub>Sb<sub>12</sub> multilayers were prepared by Pulsed Laser Deposition (PLD). Smooth, nano-crystalline, stoichiometric layers were synthetized in a classical PLD arrangement or in a special off-axis PLD arrangement, followed by Rapid thermal annealing. Results of physical characterizations such as morphology—Atomic Force Microscope, Scanning Electron Microscope, composition-Energy Dispersive X-ray analysis, crystallinity—X-ray Diffraction, separation of multilayers—Secondary of ion beam mass spectroscopy SIMS and study of thermoelectric properties such as the thermoelectric figure of merit ZT, in-plane electrical resistivity, Seebeck coefficient and thermal conductivity are presented. For thermal conductivity measurement a newly developed Atomic force thermal microscope (AFMTh) was tested. Results obtained on the single layers compared to multi-layered structures are discussed.展开更多
基金supported by the National Key Research and Development Program of China(2018YFA0704200,2017YFA0302904,2019YFA0308500,and 2018YFA0305602)the National Natural Science Foundation of China(12074414,12074002,52072401,11804379,and 11774402)+1 种基金the Recruitment Program for Leading Talent Team of Anhui Province(2019-16)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB25000000)。
文摘The iron-based nontoxic chalcogenide superconductor Fe(Te,Se)has great potential for high magnetic field applications while it lacks a reliable method to produce bulk superconductor so far.Here we report a one-step synthesis method to grow high-quality Fe(Te,Se)single crystals free of interstitial iron atoms through minor Mn doping.Bulk superconductivity is revealed in the as-grown centimetersized crystals with the optimal doping level of 1% Fe atoms substituted by Mn,which is systematically demonstrated by sharp electrical resistivity and magnetic susceptibility transitions,and large specific heat jumps.Compared with the undoped sample,the optimally doped one shows a significantly enhanced upper critical field,and a large self-field critical current density J_(c) of 4.5×10^(5)A cm^(-2) at 2 K(calculated by the Bean model),which maintains large values under high fields.The absence of interstitial iron atoms is testified by the scanning tunneling microscopy,and the effect of Mn doping is discussed.Our results provide a practical method by minor Mn doping to directly synthesize high-performance Fe(Te,Se)bulks that allow for future high-field superconducting applications.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00103,2012CB821404,and 2009CB929104)the National Natural Science Foundation of China(Grant Nos.10974175,10934005,and 11204059)+1 种基金the Natural Science Foundation of Zhejiang Province,China(Grant No.Q12A040038)the Fundamental Research Funds for the Central Universities of China
文摘Iron-chalcogenide compounds with FeSe（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10974175 and 10934005)the National Basic Research Program of China (Grant No. 2009CB929104)the PCSIRT of the Ministry of Education of China (Grant No. IRT0754)
文摘We have synthesized polycrystalline samples of Fe1.11(Te1-xSx) and single crystals of Fe1+y(Te0.88S0.12),and characterized their properties.Our results show that the solid solution of S in the Fe1.11Te tetragonal lattice is limited,~10%.We observed superconductivity at ~8 K in both polycrystalline samples and single crystals.Magnetization measurements reveal that the volume fraction is small for this superconducting phase in both polycrystalline samples as-synthesized and single crystals as-grown.It is found that annealing in air enhances the superconducting fraction;the maximum fraction is almost 100% in the single crystals annealed in air at 300°C.We discuss the effect of annealing on superconductivity and transport properties at the normal state in the Fe1+y(Te1-xSx) system in terms of decrease of the excess Fe.
文摘开展6 000和10 000 k N·m能级强夯的现场试验,以强夯前后多道瞬态面波测试和重型动力触探试验方法,对强夯处理效果进行测试。试验结果表明:强夯加固处理后地基承载力和土体工程特性得到改善,但地基承载力特征值和压缩模量局部深度仍不能满足设计要求;6 000和10 000 k N·m能级有效加固深度分别为6.0~7.0 m和7.0~8.0 m;10 000 k N·m能级试验区浅层加固处理效果较差,与浅层存在淤泥质土、夯坑回填方式及第3遍夯点间距过大和夯能过小等因素有关,需采取相应的处理措施。
文摘Thermoelectric layers as Bi<sub>2</sub>Te<sub>3</sub>, Yb<sub>0.19</sub>Co<sub>4</sub>Sb<sub>12</sub>, FeSb<sub>2</sub>Te, Ce<sub>0.1</sub>Fe<sub>0.7</sub>Co<sub>3.3</sub>Sb<sub>12</sub> and FeSb<sub>2</sub>Te/Ce<sub>0.1</sub>Fe<sub>0.7</sub>Co<sub>3.3</sub>Sb<sub>12</sub> multilayers were prepared by Pulsed Laser Deposition (PLD). Smooth, nano-crystalline, stoichiometric layers were synthetized in a classical PLD arrangement or in a special off-axis PLD arrangement, followed by Rapid thermal annealing. Results of physical characterizations such as morphology—Atomic Force Microscope, Scanning Electron Microscope, composition-Energy Dispersive X-ray analysis, crystallinity—X-ray Diffraction, separation of multilayers—Secondary of ion beam mass spectroscopy SIMS and study of thermoelectric properties such as the thermoelectric figure of merit ZT, in-plane electrical resistivity, Seebeck coefficient and thermal conductivity are presented. For thermal conductivity measurement a newly developed Atomic force thermal microscope (AFMTh) was tested. Results obtained on the single layers compared to multi-layered structures are discussed.
