Anomalous bond lengthening in compressed magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)

Applying pressure has been evidenced as an effective method to control the properties of semiconductors,owing to its capability to modify the band configuration around Fermi energy.Correspondingly,structural evolutions under external pres-sures are required to analyze the mechanisms.Herein high-pressure structure of a magnetic doped semiconductor Ba(Zn_(0.95)Mn_(0.05))_(2)As_(2)is studied with combination of in-situ synchrotron X-ray diffractions and diamond anvil cells.The materials become ferromagnetic with Curie temperature of 105 K after further 20%K doping.The title material undergoes an isostruc-tural phase transition at around 19 GPa.Below the transition pressure,it is remarkable to find lengthening of Zn/Mn-As bond within Zn/MnAs layers,since chemical bonds are generally shortened with applying pressures.Accompanied with the bond stretch,interlayer As-As distances become shorter and the As-As dimers form after the phase transition.With further compres-sion,Zn/Mn-As bond becomes shortened due to the recovery of isotropic compression on the Zn/MnAs layers.

Colossal negative magnetoresistance in spin glass Na(Zn,Mn)Sb

We report the study of magnetic and transport properties of polycrystalline and single crystal Na(Zn,Mn)Sb,a new member of“111”type of diluted magnetic materials.The material crystallizes into Cu2Sb-type structure which is isostructural to“111”type Fe-based superconductors.With suitable carrier and spin doping,the Na(Zn,Mn)Sb establishes spin-glass ordering with freezing temperature(Tf)below 15 K.Despite lack of long-range ferromagnetic ordering,Na(Zn,Mn)Sb single crystal still shows sizeable anomalous Hall effect below Tf.Carrier concentration determined by Hall effect measurements is over 1019 cm-3.More significantly,we observe colossal negative magnetoresistance(MR≡[ρ(H)−ρ(0)]/ρ(0))of-94%in the single crystal sample.

Advances in new generation diluted magnetic semiconductors with independent spin and charge doping

As one branch of spintronics, diluted magnetic semiconductors (DMSs) are extensively investigated due to their fundamental significance and potential application in modern information society. The classical materials (Ga,Mn)As of III-V group based DMSs has been well studied for its high compatibility with the high-mobility semiconductor GaAs. But the Curie temperature in (Ga,Mn)As film is still far below room temperature because the spin & charge doping is bundled to the same element that makes the fabrication very difficult. Alternatively, the discovery of a new generation DMSs with independent spin and charge doping, such as (Ba,K)(Zn,Mn)2As2 (briefly named BZA), attracted considerable attention due to their unique advantages in physical properties and heterojunction fabrication. In this review we focus on this series of new DMSs including (I) materials in terms of three types of new DMSs, i.e. the "111","122" and "1111" system;(II) the physical properties of BZA;(III) single crystals & prototype device based on BZA. The prospective of new type of DMSs with independent spin and charge doping is briefly discussed.

Propagating slow sausage waves in a sunspot observed by the New Vacuum Solar Telescope

A sunspot is an ideal waveguide for a variety of magnetohydrodynamic waves,which carry a significant amount of energy to the upper atmosphere and could be used as a tool to probe the magnetic and thermal structure of a sunspot.In this study,we used the New Vacuum Solar Telescope and took highresolution image sequences simultaneously in both Ti O(7058±10?A)and Hα(6562±2.5?A)bandpasses.We extracted the area and total emission intensity variations of sunspot umbra and analyzed the signals with synchrosqueezing transform.We found that the area and emission intensity varied with both three and five minute periodicity.Moreover,the area and intensity oscillated in phase with each other,this fact hold in both Ti O and Hαdata.We interpret this oscillatory signal as a propagating slow sausage wave.The propagation speed is estimated at about 8 km s^-1.We infer that this sunspot's umbra could have temperature as low as 2800–3500 K.

Synthesis, structure, and properties of Ba9Co3Se(15) with one-dimensional spin chains

A new compound with one-dimensional spin chains, Ba9Co3Se(15), was synthesized under high pressure and high temperature conditions and systematically characterized via structural, transport and magnetic measurements. Ba9Co3Se(15) crystallizes in a hexagonal structure with the space group P-6c2(No. 188) and lattice constants of a = b = 9.6765 ? and c = 18.9562 ?. The structure consists of trimeric face-sharing octahedral CoSe6 chains, which are arranged in a triangular lattice in the ab-plane and separated by Ba atoms. The distance of the nearest neighbor of CoSe6 chains is very large, given by the lattice constant a = 9.6765 ?. The Weiss temperature Tθ associated with the intra-chain coupling strength is about -346 K. However, no long-range magnetic order but a spin glass transition at ~ 3 K has been observed. Our results indicate that the spin glass behavior in Ba9Co3Se(15) mainly arises from the magnetic frustration due to the geometrically frustrated triangular lattice.

Structure-Spin-Transport Anomaly in Quasi-One-Dimensional Ba9Fe3Te15 under High Pressure

Recently,a series of novel compounds Ba3MX5(M=Fe,Ti,V;X=Se,Te)with hexagonal crystal structures composed of quasi-1-dimensional(1D)magnetic chains has been synthesized by our research team using high-pressure and high-temperature methods.The initial hexagonal phases persist to the maximum achievable pressure,while spin configurations and magnetic interactions may change dramatically as a result of considerable reductions in interchain separations upon pressurization.These compounds therefore offer unique possibilities for studying the evolution of intrinsic electronic structures in quasi-1D magnetic systems.Here we present a systematic investigation of Ba9Fe3Te15,in which the interchain separations between trimerized 1D chains(~10.2Å)can be effectively modulated by external high pressure.The crystal structure especially along the 1D chains exhibits an abnormal expansion at^GPa,which accompanies trimerization entangled anomalous mixed-high-low spin transition.An insulator-metal transition has been observed under high pressure as a result of charge-transfer gap closing.Pressure-induced superconductivity emerges at 26 GPa,where the charge-transfer gap fully closes,3D electronic configuration forms and local spin fully collapses.

Defect-manipulated magnetoresistance and above-room-temperature ferromagnetism in two-dimensional BaNi_(2)V_(2)O_(8)

The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics.Here,we report a quantum-magnetic system BaNi_(2)V_(2)O_(8)(BNVO),in which the spin correlation was modulated by unusual oxidation state,leading to different magnetic behavior.The BNVO was modified with topochemical reduction(TR)to yield TR-BNVO with partially reduced valance state of Ni^(+)in the two-dimensional NiO_(6)-honeycomb lattice.Accordingly,the antiferromagnetic order is suppressed by the introduction of locally interposed Ni^(+)and oxygen vacancies,resulting in a ferromagnetic ground state with the transition temperature up to 710 K.A positive magnetoresistance(7.5%)was observed in the TR-BNVO at 40 K under 7 T.These findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.

Superconductivity above 70 K observed in lutetium polyhydrides

The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique.The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity(SC).The superconducting transition with a maximum onset temperature(Tc)71 K was observed at pressure of 218 GPa in the experiments.The Tcdecreased to 65 K when pressure was at 181 GPa.From the evolution of SC at applied magnetic fields,the upper critical field at zero temperatureμ0Hc2(0)was obtained to be~36 T.The in-situ high pressure X-ray diffraction experiments imply that the high TcSC should arise from the Lu4H23phase with Pm3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.

Pressure-Induced Intermetallic Charge Transfer and Semiconductor- Metal Transition in Two-Dimensional AgRuO_(3)

The intricate correlation between charge degrees of freedom and physical properties is a fascinating area of research in solid state chemistry and condensed matter physics.Herein,we report on the pressureinduced successive charge transfer and accompanied resistive evolution in honeycomb layered ruthenate AgRuO_(3).Structural revisiting and spectroscopic analyses affirm the ilmenite type R-3 structure with mixed valence cations as Ag^(+1/+2)Ru^(+4/+5)O_(3) at ambient pressure.In-situ pressure-and temperature-dependent resistance variation reveals a successive insulatormetal-insulator transition upon pressing,accompanied by unprecedented charge transfer between Ag and Ru under applied pressure,and a further structural phase transition in the insulator region at higher pressure.These phenomena are also corroborated by in-situ pressure-dependent Raman spectra,synchrotron X-ray diffraction,bond valence sums,and electronic structure calculations,emphasizing the dominated rare Ag2+,and near zero thermal expansion in the ab-plane in the metallic zone mostly due to the Jahn-Teller effect of d9-Ag2+.The multiple electronic instabilities in AgRuO_(3) may offer new possibilities toward novel and unconventionally physical and chemical behaviors in strongly correlated honeycomb lattices.

护理临床带教教师软技能现状及其对带教行为的影响

目的调查护理临床带教教师护理软技能现状并探讨其对带教行为的影响,为开展临床带教教师培训、提高临床带教教师综合素质提供借鉴和参考。方法采用一般资料调查表、护理软技能测评量表和临床护理教师行为量表对北京市4所三级甲等医院的340名护理临床带教教师进行调查。结果护理临床带教教师护理软技能得分为(160.24±14.62)分,认知技能维度得分稍低,带教行为得分为(98.88±10.41)分;护理软技能水平和教师带教行为具有正相关性(P<0.01);分层回归分析结果显示,护理软技能独立解释带教行为变异的27.9%。结论护理临床带教教师护理软技能水平一般,带教行为较好,护理软技能是带教行为的重要影响因素。护理管理者可通过针对性的措施提高护理临床带教教师的软技能水平,从而改善其教学行为。

Ferromagnetism at 230 K in(Ba_(0.7)K_(0.3))(Zn_(0.85)Mn_(0.15))_2As_2 diluted magnetic semiconductor

We report the ferromagnetism with Cure temperature Tcat 230 K in a new diluted magnetic semiconductor(DMS)(Ba0.7K0.3)(Zn0.85Mn0.15)2As2isostructural to ferropnictide 122 superconductors synthesized via low temperature sintering.Spin is doped by isovalence substitution of Mn2+for Zn2+,while charge is introduced by heterovalence substitution of K1+for Ba2+in(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS,being different from(Ga,Mn)As where both spin&charge are induced simultaneously by heterovalence substation of Mn2+for Ga3+.The(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS shows spontaneous magnetization following T3/2dependence expected for a homogeneous ferromagnet with saturation moment 1.0μB for each Mn atom.

用于阴离子识别的二茂铁基偶氮苯化合物的合成（英文）

目的:研究二茂铁基偶氮苯化合物的光电响应性能及离子识别性能,并研究取代基对其离子识别性能的影响。创新点:考察取代基对于二茂铁基偶氮苯化合物的影响,并提出可能的机理。方法:循环伏安(CV)法和紫外可见吸收光谱(UV-vis)法。结论:通过CV法和UV-vis法研究二茂铁基偶氮苯化合物的离子识别性能,发现硝基取代的化合物对于F^-和H_2PO_4^-具有选择性离子识别作用,而氨基取代的化合物则识别作用不明显。

Highly conductive and transparent metal-organic frameworks thin film

Energy crisis has aroused global concern and needs to be solved immediately. A series of serious environmental problems caused by the unlimited use of trad让ional fossil fuels like petroleum and charcoal, such as rising sea levels and melting glaciers, have dangerously threatened human destiny [ 1 ]. It is an effective choice to look for new energy sources to replace the lim让ed fossil fuel reserves. Among these new energy sources, solar energy stands out and attracts tremendous attention because of its environmental friendliness, stability, renewability, and universality [2-5]. Transparent and conductive electrode is the vital part in photoelectric conversion devices [6]. Indium tin oxide (ITO) is the most popular transparent and conductive electrode material at present [7]. However, the limited reserves of indium, a component in ITO has resulted in the high price of ITO electrode, restricting its wide application.

Superconducting properties of “111” type LiFeAs iron arsenide single crystals

LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity with spin wave density.

High-pressure synthesis,crystal structure and physical properties of a new Cr-based arsenide La3CrAs5

In La-Cr-As system,the first ternary compound La3CrAs5 has been successfully synthesized under highpressure and high-temperature conditions.La3CrAs5 crystallizes into a hexagonal Hf5Sn3Cu-anti type structure with a space group of P63/mcm(No.193)and lattice parameters of a=b=8.9845A and c=5.8897A.The structure contains facesharing octahedral CrAs6 chains along the c-axis,which are arranged triangularly in the ab-plane and separated by a significantly large distance of 8.9845A.The magnetic properties,resistivity and specific heat measurements were performed.La3CrAs5 exhibits a metallic state with Fermi liquid behavior at low temperatures and undergoes a ferromagnetic transition at Curie temperature TC^50 K.First-principles theoretical studies were conducted to calculate its band structure and density of states(DOS),which indicated that the non-negligible contribution of La to the DOS near the Fermi level caused La3CrAs5 to be a three-dimensional(3D)metal.The crystal orbital Hamilton population(-COHP)was also calculated to explain the global stability and bonding characteristics in the structure of La3CrAs5.