Bandgap engineering of semiconductor nanomaterials is critical for their applications in nanoelectronics, opto- electronics, and photonics. Here we report, for the first time, the growth of single-crystalline quaterna...Bandgap engineering of semiconductor nanomaterials is critical for their applications in nanoelectronics, opto- electronics, and photonics. Here we report, for the first time, the growth of single-crystalline quaternary alloyed Ga0.75In0.25As0.49Sb0.51 nanowires via a chemical-vapor-deposition method. The synthesized nanowires have a uniform composition distribution along the growth direction, with a zinc-blende structure. In the photoluminescence investigation, these quaternary alloyed semiconductor nanowires show a strong band edge light emission at 1950 nm （0.636 eV）. Photodetectors based on these alloy nanowires show a strong light response in the near-infrared region （980 nm） with the external quantum efficiency of 2.0 × 104% and the responsivity of 158 A/W. These novel near-infrared photodetectors may find promising applications in integrated infrared photodetection, information communication, and processing.展开更多
Quaternary alloys Mg2Sn0.4Si0.6-xGex （x=0, 0.02, 0.05, 0.08 0.1, and 0.2） were prepared using induction melting followed by hot-pressing. Relative densities of the sintered samples were over 97% of the theoretical v...Quaternary alloys Mg2Sn0.4Si0.6-xGex （x=0, 0.02, 0.05, 0.08 0.1, and 0.2） were prepared using induction melting followed by hot-pressing. Relative densities of the sintered samples were over 97% of the theoretical values. Multiple phases were detected in the samples. It was found that the Seebeck coefficient was sensitive to the content of Mg2Ge and a maximum value of about 350 μV-K^-1 was obtained. The introduction of Ge increases the electrical conductivity and the thermal conductivity simultaneously. The mechanism of this phenomenon was discussed. A maximum dimensionless figure of merit, ZT, of about 0.28 was obtained for Mg2Sn0.4Si0.55Ge0.05 at 550 K.展开更多
The melt spun ribbons of Al-La-Y-Ni(Fe)quaternary alloys were prepared by a single- roller melt spinning technique in vacuum.Their amorphous nature,mechanical properties and tensile fracture surface morphology were in...The melt spun ribbons of Al-La-Y-Ni(Fe)quaternary alloys were prepared by a single- roller melt spinning technique in vacuum.Their amorphous nature,mechanical properties and tensile fracture surface morphology were investigated.The experimental results show that amorphous alloys with high strength and good ductility as well as good thermal stability can be achieved in Al-La-Y-Ni(Fe)system,when the alloy contains 85—90 at.-% Al and less than 10 at.-% La+Y.The maximum tensile fracture strength(σ_f) and microhardness(HV)are as high as 760 MPa and 294 DPN,respectively.The as- quenched ribbons can be bent 180 degree without fracturing.The dominant factors for formation of amorphous Al-La-Y-Ni(Fe)are the strong attractive interaction among Al, La,Y and a decrease of melting temperature.展开更多
Using the first-principles calculations,we study the structural,electronic,and magnetic properties along with exchange interactions and Curie temperatures for CrZrCoZ(Z=Al,Ga,In,Tl,Si,Pb)quaternary Heusler alloys.The ...Using the first-principles calculations,we study the structural,electronic,and magnetic properties along with exchange interactions and Curie temperatures for CrZrCoZ(Z=Al,Ga,In,Tl,Si,Pb)quaternary Heusler alloys.The results show that the CrZrCoZ alloys are half-metallic ferrimagnets,and their total spin magnetic moments,which are mainly carried by the Cr atom,obey the Slater-Pauling rule.Analysis of local density of states confirms that the exchange splitting between eg and t2g states leads to the formation of half-metallic gap.According to the calculated Heisenberg exchange coupling parameters,it is found that the Cr(A)-Cr(A)and Cr(A)-Zr(B)exchanges dominate the appearance of ferrimagnetic states in CrZrCoZ(Z=Al,Ga,In,Tl,Pb)alloys,and it is the Cr(A)-Zr(B)and Zr(B)-Zr(B)exchanges for CrZrCoSi alloy.Finally,we estimate the Curie temperatures of CrZrCoZ by using mean-field approximation,it is found that the CrZrCoZ(Z=Al,Ga,In,Tl,Pb)alloys have noticeably higher Curie temperatures than room temperature.So,we expect that the CrZrCoZ alloys are promising candidates in spintronic applications in future.展开更多
Ni-Ti-based shape memory alloys(SMAs)have found widespread use in the last 70 years,but improving their functional stability remains a key quest for more robust and advanced applications.Named for their ability to ret...Ni-Ti-based shape memory alloys(SMAs)have found widespread use in the last 70 years,but improving their functional stability remains a key quest for more robust and advanced applications.Named for their ability to retain their processed shape as a result of a reversible martensitic transformation,SMAs are highly sensitive to compositional variations.Alloying with ternary and quaternary elements to finetune the lattice parameters and the thermal hysteresis of an SMA,therefore,becomes a challenge in materials exploration.Combinatorial materials science allows streamlining of the synthesis process and data management from multiple characterization techniques.In this study,a composition spread of Ni-Ti-Cu-V thin-film library was synthesized by magnetron co-sputtering on a thermally oxidized Si wafer.Composition-dependent phase transformation temperature and microstructure were investigated and determined using high-throughput wavelength dispersive spectroscopy,synchrotron X-ray diffraction,and temperature-dependent resistance measurements.Of the 177 compositions in the materials library,32 were observed to have shape memory effect,of which five had zero or near-zero thermal hysteresis.These compositions provide flexibility in the operating temperature regimes that they can be used in.A phase map for the quaternary system and correlations of functional properties are discussed w让h respect to the local microstructure and composition of the thin-film library.展开更多
材料质量好坏对于获得高性能红外探测器至关重要。提出决定材料质量的关键点在于精准控制材料结构中层与层之间的晶格失配度,报道了晶格失配对材料质量和器件暗电流性能的影响。实验结论表明在液相外延技术生长的InAs/InAsSbP材料体系中...材料质量好坏对于获得高性能红外探测器至关重要。提出决定材料质量的关键点在于精准控制材料结构中层与层之间的晶格失配度,报道了晶格失配对材料质量和器件暗电流性能的影响。实验结论表明在液相外延技术生长的InAs/InAsSbP材料体系中,InAs和InAsSbP间的晶格失配不是越小越好,而是有一个最佳值。如果晶格失配偏离这个值,不管是偏大还是偏小,材料的质量都会恶化。阐述了如何调整生长参数以获得合适的晶格失配度。制备了具有适宜晶格失配度的红外探测器件,该探测器零偏压下的室温峰值探测率为6.8×10^(9) cm Hz^(1/2)W^(-1),与国际商用InAs探测器的指标相当。展开更多
On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd（Gd<25% atom fraction） quaternary system has been studied by means of X-ray diffraction analysis, diffe...On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd（Gd<25% atom fraction） quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy. The 700℃ isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd （Gd≤25% atom fraction） phase diagrams were determined respectively. And the 700℃ isothermal section of the Pd-Ag-Ru-Gd （Gd≤25% atom fraction） quaternary system phase diagram was finally inferred. The section consists of four single-phase regions: solid solution Pd（Ag）, （Ru）, Pd3Gd and Ag 51 Gd 14 ; five two-phase regions: Pd（Ag）+（Ru）, Pd（Ag）+ Ag 51 Gd 14 , （Ru）+ Ag 51 Gd 14 , Pd（Ag）+ Pd3Gd and （Ru）+ Pd3Gd; three three-phase regions: Pd（Ag）+ Pd3Gd+（Ru）, Pd（Ag）+ Ag 51 Gd 14 +（Ru） and （Ru）+ Ag 51 Gd 14 + Pd3Gd; one four-phase region Pd（Ag）+ （Ru）+ Ag 51 Gd 14 + Pd3Gd. No new quaternary intermetallic phase is found.展开更多
通过对壳聚糖(CS)进行改性,成功制备了壳聚糖季铵盐(HACC)。经过FT-IR、1 H NMR表征,证实了其分子结构。采用在仿生溶液中添加CS或HACC的方法,在微弧氧化前后的镁合金样品表面修饰得到4种不同的仿生涂层。利用SEM和XRD对涂层分析表明,...通过对壳聚糖(CS)进行改性,成功制备了壳聚糖季铵盐(HACC)。经过FT-IR、1 H NMR表征,证实了其分子结构。采用在仿生溶液中添加CS或HACC的方法,在微弧氧化前后的镁合金样品表面修饰得到4种不同的仿生涂层。利用SEM和XRD对涂层分析表明,仿生矿化后的镁合金表面为含有CaP/CS或CaP/HACC的复合涂层。降解实验表明,微弧氧化后仿生矿化的样品失重率小于微弧氧化前仿生矿化的样品;利用ICP测定释放的镁、铝离子浓度,发现镁离子浓度先升高后降低,铝离子浓度越来越小。抑菌实验结果表明,含有CaP/HACC比含有CaP/CS的复合涂层样品对金黄色葡萄球菌具有更明显的抑菌作用;对于仿生溶液中添加同样浓度的CS或HACC,微弧氧化后比微弧氧化前矿化的样品抑菌率高。比浊法测定显示,4种涂层在4d内均具有不同程度的抑菌效果,微弧氧化后的镁合金样品在添加有HACC的仿生溶液中矿化得到的涂层抑菌率最高。研究说明,改性后的HACC比CS具有更强的抑菌作用;微弧氧化后的样品具有更强的抗腐蚀能力和载药性能。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51525202,61505051,1137049,61474040,and 61635001)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,Chinathe Fundamental Research Funds for the Central Universities,China
文摘Bandgap engineering of semiconductor nanomaterials is critical for their applications in nanoelectronics, opto- electronics, and photonics. Here we report, for the first time, the growth of single-crystalline quaternary alloyed Ga0.75In0.25As0.49Sb0.51 nanowires via a chemical-vapor-deposition method. The synthesized nanowires have a uniform composition distribution along the growth direction, with a zinc-blende structure. In the photoluminescence investigation, these quaternary alloyed semiconductor nanowires show a strong band edge light emission at 1950 nm （0.636 eV）. Photodetectors based on these alloy nanowires show a strong light response in the near-infrared region （980 nm） with the external quantum efficiency of 2.0 × 104% and the responsivity of 158 A/W. These novel near-infrared photodetectors may find promising applications in integrated infrared photodetection, information communication, and processing.
基金supported by the National Natural Science Foundation of China (No.50522203, 50731006)the National Basic Research Program of China (No.2007CB607502)
文摘Quaternary alloys Mg2Sn0.4Si0.6-xGex （x=0, 0.02, 0.05, 0.08 0.1, and 0.2） were prepared using induction melting followed by hot-pressing. Relative densities of the sintered samples were over 97% of the theoretical values. Multiple phases were detected in the samples. It was found that the Seebeck coefficient was sensitive to the content of Mg2Ge and a maximum value of about 350 μV-K^-1 was obtained. The introduction of Ge increases the electrical conductivity and the thermal conductivity simultaneously. The mechanism of this phenomenon was discussed. A maximum dimensionless figure of merit, ZT, of about 0.28 was obtained for Mg2Sn0.4Si0.55Ge0.05 at 550 K.
文摘The melt spun ribbons of Al-La-Y-Ni(Fe)quaternary alloys were prepared by a single- roller melt spinning technique in vacuum.Their amorphous nature,mechanical properties and tensile fracture surface morphology were investigated.The experimental results show that amorphous alloys with high strength and good ductility as well as good thermal stability can be achieved in Al-La-Y-Ni(Fe)system,when the alloy contains 85—90 at.-% Al and less than 10 at.-% La+Y.The maximum tensile fracture strength(σ_f) and microhardness(HV)are as high as 760 MPa and 294 DPN,respectively.The as- quenched ribbons can be bent 180 degree without fracturing.The dominant factors for formation of amorphous Al-La-Y-Ni(Fe)are the strong attractive interaction among Al, La,Y and a decrease of melting temperature.
基金Project supported by the National Natural Science Foundation of China(Grant No.11864021)Foundation of A Hundred Youth Talents Training Program of Lanzhou Jiaotong University,China,the Key Talent Foundation of Gansu Province,China(Grant No.2020RCXM100)Excellent Research Team of Lanzhou Jiaotong University,China(Grant No.201803).
文摘Using the first-principles calculations,we study the structural,electronic,and magnetic properties along with exchange interactions and Curie temperatures for CrZrCoZ(Z=Al,Ga,In,Tl,Si,Pb)quaternary Heusler alloys.The results show that the CrZrCoZ alloys are half-metallic ferrimagnets,and their total spin magnetic moments,which are mainly carried by the Cr atom,obey the Slater-Pauling rule.Analysis of local density of states confirms that the exchange splitting between eg and t2g states leads to the formation of half-metallic gap.According to the calculated Heisenberg exchange coupling parameters,it is found that the Cr(A)-Cr(A)and Cr(A)-Zr(B)exchanges dominate the appearance of ferrimagnetic states in CrZrCoZ(Z=Al,Ga,In,Tl,Pb)alloys,and it is the Cr(A)-Zr(B)and Zr(B)-Zr(B)exchanges for CrZrCoSi alloy.Finally,we estimate the Curie temperatures of CrZrCoZ by using mean-field approximation,it is found that the CrZrCoZ(Z=Al,Ga,In,Tl,Pb)alloys have noticeably higher Curie temperatures than room temperature.So,we expect that the CrZrCoZ alloys are promising candidates in spintronic applications in future.
基金The author thanks Tieren Gao,Peer Decker,Alan Savan,and Manfred Wuttig for fruitful discussions.The authors gratefully acknowledge funding support by the National Science Foundation Graduate Research Fellowship Program(DGE 1322106).
文摘Ni-Ti-based shape memory alloys(SMAs)have found widespread use in the last 70 years,but improving their functional stability remains a key quest for more robust and advanced applications.Named for their ability to retain their processed shape as a result of a reversible martensitic transformation,SMAs are highly sensitive to compositional variations.Alloying with ternary and quaternary elements to finetune the lattice parameters and the thermal hysteresis of an SMA,therefore,becomes a challenge in materials exploration.Combinatorial materials science allows streamlining of the synthesis process and data management from multiple characterization techniques.In this study,a composition spread of Ni-Ti-Cu-V thin-film library was synthesized by magnetron co-sputtering on a thermally oxidized Si wafer.Composition-dependent phase transformation temperature and microstructure were investigated and determined using high-throughput wavelength dispersive spectroscopy,synchrotron X-ray diffraction,and temperature-dependent resistance measurements.Of the 177 compositions in the materials library,32 were observed to have shape memory effect,of which five had zero or near-zero thermal hysteresis.These compositions provide flexibility in the operating temperature regimes that they can be used in.A phase map for the quaternary system and correlations of functional properties are discussed w让h respect to the local microstructure and composition of the thin-film library.
基金Supported by the National Natural Science Foundation of China (11933006)the Frontier Science Research Project (Key Programs) of the Chinese Academy of Sciences (QYZDJ-SSW-SLH018)the National Natural Science Foundation of China (U2141240)。
文摘材料质量好坏对于获得高性能红外探测器至关重要。提出决定材料质量的关键点在于精准控制材料结构中层与层之间的晶格失配度,报道了晶格失配对材料质量和器件暗电流性能的影响。实验结论表明在液相外延技术生长的InAs/InAsSbP材料体系中,InAs和InAsSbP间的晶格失配不是越小越好,而是有一个最佳值。如果晶格失配偏离这个值,不管是偏大还是偏小,材料的质量都会恶化。阐述了如何调整生长参数以获得合适的晶格失配度。制备了具有适宜晶格失配度的红外探测器件,该探测器零偏压下的室温峰值探测率为6.8×10^(9) cm Hz^(1/2)W^(-1),与国际商用InAs探测器的指标相当。
文摘On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd（Gd<25% atom fraction） quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy. The 700℃ isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd （Gd≤25% atom fraction） phase diagrams were determined respectively. And the 700℃ isothermal section of the Pd-Ag-Ru-Gd （Gd≤25% atom fraction） quaternary system phase diagram was finally inferred. The section consists of four single-phase regions: solid solution Pd（Ag）, （Ru）, Pd3Gd and Ag 51 Gd 14 ; five two-phase regions: Pd（Ag）+（Ru）, Pd（Ag）+ Ag 51 Gd 14 , （Ru）+ Ag 51 Gd 14 , Pd（Ag）+ Pd3Gd and （Ru）+ Pd3Gd; three three-phase regions: Pd（Ag）+ Pd3Gd+（Ru）, Pd（Ag）+ Ag 51 Gd 14 +（Ru） and （Ru）+ Ag 51 Gd 14 + Pd3Gd; one four-phase region Pd（Ag）+ （Ru）+ Ag 51 Gd 14 + Pd3Gd. No new quaternary intermetallic phase is found.
文摘通过对壳聚糖(CS)进行改性,成功制备了壳聚糖季铵盐(HACC)。经过FT-IR、1 H NMR表征,证实了其分子结构。采用在仿生溶液中添加CS或HACC的方法,在微弧氧化前后的镁合金样品表面修饰得到4种不同的仿生涂层。利用SEM和XRD对涂层分析表明,仿生矿化后的镁合金表面为含有CaP/CS或CaP/HACC的复合涂层。降解实验表明,微弧氧化后仿生矿化的样品失重率小于微弧氧化前仿生矿化的样品;利用ICP测定释放的镁、铝离子浓度,发现镁离子浓度先升高后降低,铝离子浓度越来越小。抑菌实验结果表明,含有CaP/HACC比含有CaP/CS的复合涂层样品对金黄色葡萄球菌具有更明显的抑菌作用;对于仿生溶液中添加同样浓度的CS或HACC,微弧氧化后比微弧氧化前矿化的样品抑菌率高。比浊法测定显示,4种涂层在4d内均具有不同程度的抑菌效果,微弧氧化后的镁合金样品在添加有HACC的仿生溶液中矿化得到的涂层抑菌率最高。研究说明,改性后的HACC比CS具有更强的抑菌作用;微弧氧化后的样品具有更强的抗腐蚀能力和载药性能。
