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CN 11-5639/O4
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Influence of matrigel on the shape and dynamics of cancer cells Hot!

Teng Ye(叶腾), Feng Qiu(邱峰)
Chin. Phys. B, 2019, 28 (10): 108704 doi: 10.1088/1674-1056/ab4275
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The interaction between extracellular matrices and cancer cells plays an important role in regulating cancer cell behaviors. In this article, we use matrigel to mimic extracellular matrices and investigate experimentally how matrigel influences the shape and dynamics of breast cancer cells (MDA-MB-231-GFP cells). We find that matrigel facilitates cancer cells' migration and shape deformation. The influences of the matrigel concentration are also reported.

Robust two-gap strong coupling superconductivity associated with low-lying phonon modes in pressurized Nb5Ir3O superconductors Hot!

Bosen Wang(王铂森), Yaoqing Zhang(张尧卿), Shuxiang Xu(徐淑香), Kento Ishigaki, Kazuyuki Matsubayashi, Jin-Guang Cheng(程金光), Hideo Hosono, Yoshiya Uwatoko
Chin. Phys. B, 2019, 28 (10): 107401 doi: 10.1088/1674-1056/ab4047
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We report robust superconducting state and gap symmetry of Nb5Ir3O via electrical transport and specific heat measurements. The analysis of specific heat manifests that Nb5Ir3O is a strongly coupled superconductor with ΔC/γnTc~1.91 and double s-wave superconducting gaps of 2L(0)/kBTc~6.56 and 2S(0)/kBTc~2.36 accounting for 90% and 10%, respectively. The (Cp-γnT)/T3 vs. T plot shows a broad peak at~23 K, indicating phonon softening and the appearance of low-lying phonon mode associated with the interstitial oxygen. This behavior explains the monotonic increase of Tc in Nb5Ir3O(1-δ) by strengthening the electron-phonon coupling and enlarging the density of states at Fermi level. The Hall coefficient is temperature independent below 200 K, and changes its sign from positive to negative above 250 K, suggesting that carrier is across the hole- to electron-dominant regions and the multi-band electronic structures. On warming, the resistivity shows a gradual crossover from T2- to T3-dependence at a critical temperature T*, and a broad peak at a temperature Tp. The reduced Tc under pressure is linearly correlated with lattice parameters c/a ratio and Tp, suggesting the important phonon contributions in Nb5Ir3O as a phonon-medicated superconductor. Possible physical mechanisms are proposed.

Electronic structure of molecular beam epitaxy grown 1T'-MoTe2 film and strain effect Hot!

Xue Zhou(周雪), Zeyu Jiang(姜泽禹), Kenan Zhang(张柯楠), Wei Yao(姚维), Mingzhe Yan(颜明哲), Hongyun Zhang(张红云), Wenhui Duan(段文晖), Shuyun Zhou(周树云)
Chin. Phys. B, 2019, 28 (10): 107307 doi: 10.1088/1674-1056/ab43ba
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Atomically thin transition metal dichalcogenide films with distorted trigonal (1T') phase have been predicted to be candidates for realizing quantum spin Hall effect. Growth of 1T' film and experimental investigation of its electronic structure are critical. Here we report the electronic structure of 1T'-MoTe2 films grown by molecular beam epitaxy (MBE). Growth of the 1T'-MoTe2 film depends critically on the substrate temperature, and successful growth of the film is indicated by streaky stripes in the reflection high energy electron diffraction (RHEED) and sharp diffraction spots in the low energy electron diffraction (LEED). Angle-resolved photoemission spectroscopy (ARPES) measurements reveal a metallic behavior in the as-grown film with an overlap between the conduction and valence bands. First principles calculation suggests that a suitable tensile strain along the a-axis direction is needed to induce a gap to make it an insulator. Our work not only reports the electronic structure of MBE grown 1T'-MoTe2 films, but also provides insights for strain engineering to make it possible for quantum spin Hall effect.

Structural and electronic properties of transition-metal chalcogenides Mo5S4 nanowires Hot!

Ming-Shuai Qiu(邱明帅), Huai-Hong Guo(郭怀红), Ye Zhang(张也), Bao-Juan Dong(董宝娟), Sajjad Ali(阿里.萨贾德), Teng Yang(杨腾)
Chin. Phys. B, 2019, 28 (10): 106103 doi: 10.1088/1674-1056/ab3f9a
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Transition-metal chalcogenide nanowires (TMCN) as a viable candidate for nanoscale applications have been attracting much attention for the last few decades. Starting from the rigid building block of M6 octahedra (M=transition metal), depending on the way of connection between M6 and decoration by chalcogenide atoms, multiple types of extended TMCN nanowires can be constructed based on some basic rules of backbone construction proposed here. Note that the well-known Chevrel-phase based M6X6 and M6X9 (X=chalcogenide atom) nanowires, which are among our proposed structures, have been successfully synthesized by experiment and well studied. More interestingly, based on the construction principles, we predict three new structural phases (the cap, edge, and C&E phases) of Mo5S4, one of which (the edge phase) has been obtained by top-down electron beam lithography on two-dimensional MoS2, and the C&E phase is yet to be synthesized but appears more stable than the edge phase. The stability of the new phases of Mo5S4 is further substantiated by crystal orbital overlapping population (COOP), phonon dispersion relation, and thermodynamic calculation. The barrier of the structural transition between different phases of Mo5S4 shows that it is very likely to realize an conversion from the experimentally achieved structure to the most stable C&E phase. The calculated electronic structure shows an interesting band nesting between valence and conduction bands of the C&E Mo5S4 phase, suggesting that such a nanowire structure can be well suitable for optoelectronic sensor applications.

Characterize and optimize the four-wave mixing in dual-interferometer coupled silicon microrings Hot!

Chao Wu(吴超), Yingwen Liu(刘英文), Xiaowen Gu(顾晓文), Shichuan Xue(薛诗川), Xinxin Yu(郁鑫鑫), Yuechan Kong(孔月婵), Xiaogang Qiang(强晓刚), Junjie Wu(吴俊杰), Zhihong Zhu(朱志宏), Ping Xu(徐平)
Chin. Phys. B, 2019, 28 (10): 104211 doi: 10.1088/1674-1056/ab3f9b
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By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the continuous-wave and pulse pumped four-wave mixing experiments to verify the dependence of conversion efficiency on the coupling conditions of the four interacting beams, respectively. Under the continuous-wave pump, the four-wave mixing efficiency gets maximized when both the pump and signal/idler beams are closely operated at the critical coupling point, while for the pulse pump case, the efficiency can be enhanced greatly when the pump and converted idler beams are all overcoupled. These experiment results agree well with our theoretical calculations. Our design provides a platform for explicitly characterizing the four-wave mixing under different pumping conditions, and offers a method to optimize the four-wave mixing, which will facilitate the development of on-chip all-optical signal processing with a higher efficiency or reduced pump power.

Manipulation of superconducting qubit with direct digital synthesis Hot!

Zhi-Yuan Li(李志远), Hai-Feng Yu(于海峰), Xin-Sheng Tan(谭新生), Shi-Ping Zhao(赵士平), Yang Yu(于扬)
Chin. Phys. B, 2019, 28 (9): 098505 doi: 10.1088/1674-1056/ab37f9
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We investigate the XY control and manipulation of the superconducting qubit state using direct digital synthesis (DDS) for the microwave pulse signal generation. The decoherence time, gate fidelity, and other qubit properties are measured and carefully characterized, and compared with the results obtained by using the traditional mixing technique for the microwave pulse generation. In particular, the qubit performance in the state manipulation with respect to the sampling rate of DDS is studied. Our results demonstrate that the present technique provides a simple and effective method for the XY control and manipulation of the superconducting qubit state. Realistic applications of the technique for the possible future scalable superconducting quantum computation are discussed.

Dipole-dipole interactions enhance non-Markovianity and protect information against dissipation Hot!

Munsif Jan, Xiao-Ye Xu(许小冶), Qin-Qin Wang(王琴琴), Zhe Chen(陈哲), Yong-Jian Han(韩永建), Chuan-Feng Li(李传锋), Guang-Can Guo(郭光灿)
Chin. Phys. B, 2019, 28 (9): 090303 doi: 10.1088/1674-1056/ab37f2
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Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies. In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel. We also consider dipole-dipole interactions (DDIs) between the system and ancilla, which are responsible for strong correlations. We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments. We show that DDIs are not only better than detuning at protecting the information (without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics. In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics. In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning. We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information.

Attacking a high-dimensional quantum key distribution system with wavelength-dependent beam splitter Hot!

Ge-Hai Du(杜舸海), Hong-Wei Li(李宏伟), Yang Wang(汪洋), Wan-Su Bao(鲍皖苏)
Chin. Phys. B, 2019, 28 (9): 090301 doi: 10.1088/1674-1056/ab343c
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The unconditional security of quantum key distribution (QKD) can be guaranteed by the nature of quantum physics. Compared with the traditional two-dimensional BB84 QKD protocol, high-dimensional quantum key distribution (HD-QKD) can be applied to generate much more secret key. Nonetheless, practical imperfections in realistic systems can be exploited by the third party to eavesdrop the secret key. The practical beam splitter has a correlation with wavelength, where different wavelengths have different coupling ratios. Using this property, we propose a wavelength-dependent attack towards time-bin high-dimensional QKD system. What is more, we demonstrate that this attacking protocol can be applied to arbitrary d-dimensional QKD system, and higher-dimensional QKD system is more vulnerable to this attacking strategy.

SymTopo:An automatic tool for calculating topological properties of nonmagnetic crystalline materials Hot!

Yuqing He(贺雨晴), Yi Jiang(蒋毅), Tiantian Zhang(张田田), He Huang(黄荷), Chen Fang(方辰), Zhong Jin(金钟)
Chin. Phys. B, 2019, 28 (8): 087102 doi: 10.1088/1674-1056/28/8/087102
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Topological materials have novel properties both in their bulk and boundaries, thereby attracting a wide interest in the theoretical and experimental communities. The recent development of the topological quantum chemistry and symmetry-based indicator theory in this field has significantly simplified the procedure for determining the topological properties of nonmagnetic crystalline materials. Accordingly, a large number of new topological materials have been found by scanning large crystal databases. This study provides details on the algorithm used in the Catalogue of Topological Electronic Materials. Moreover, based on the algorithm, we develop an automatic package named SymTopo, which calculates the symmetry representations of any given nonmagnetic crystalline material and predicts its topological properties. This package may facilitate the discovery of more topological materials in the future.

First-principles study of the band gap tuning and doping control in CdSexTe1-x alloy for high efficiency solar cell Hot!

Jingxiu Yang(杨竞秀), Su-Huai Wei(魏苏淮)
Chin. Phys. B, 2019, 28 (8): 086106 doi: 10.1088/1674-1056/28/8/086106
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CdTe is one of the leading materials for low cost, high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 eV. However, its solar to electricity power conversion efficiency (PCE) is hindered by the relatively low open circuit voltage (VOC) due to intrinsic defect related issues. Here, we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the “ideal” band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much VOC. Using the hybrid functional calculation, we find that the minimum band gap of the CdTe1-xSex alloy can be reduced from 1.48 eV at x=0 to 1.39 eV at x=0.32, and most of the change come from the lowering of the conduction band minimum. We also show that the formation of the alloy can improve the p-type doping of CuCd impurity based on the reduced effective formation energy and nearly constant effective transition energy level, thus possibly enhance VOC, thus PCE.

Non-Stokes drag coefficient in single-particle electrophoresis:New insights on a classical problem Hot!

Mai-Jia Liao(廖麦嘉), Ming-Tzo Wei(魏名佐), Shi-Xin Xu(徐士鑫), H Daniel Ou-Yang(歐陽新喬), Ping Sheng(沈平)
Chin. Phys. B, 2019, 28 (8): 084701 doi: 10.1088/1674-1056/28/8/084701
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We measured the intrinsic electrophoretic drag coefficient of a single charged particle by optically trapping the particle and applying an AC electric field, and found it to be markedly different from that of the Stokes drag. The drag coefficient, along with the measured electrical force, yield a mobility-zeta potential relation that agrees with the literature. By using the measured mobility as input, numerical calculations based on the Poisson-Nernst-Planck equations, coupled to the Navier-Stokes equation, reveal an intriguing microscopic electroosmotic flow near the particle surface, with a well-defined transition between an inner flow field and an outer flow field in the vicinity of electric double layer's outer boundary. This distinctive interface delineates the surface that gives the correct drag coefficient and the effective electric charge. The consistency between experiments and theoretical predictions provides new insights into the classic electrophoresis problem, and can shed light on new applications of electrophoresis to investigate biological nanoparticles.

Evolution of incommensurate superstructure and electronic structure with Pb substitution in (Bi2-xPbx)Sr2CaCu2O8+δ superconductors Hot!

Jing Liu(刘静), Lin Zhao(赵林), Qiang Gao(高强), Ping Ai(艾平), Lu Zhang(张璐), Tao Xie(谢涛), Jian-Wei Huang(黄建伟), Ying Ding(丁颖), Cheng Hu(胡成), Hong-Tao Yan(闫洪涛), Chun-Yao Song(宋春尧), Yu Xu(徐煜), Cong Li(李聪), Yong-Qing Cai(蔡永青), Hong-Tao Rong(戎洪涛), Ding-Song Wu(吴定松), Guo-Dong Liu(刘国东), Qing-Yan Wang(王庆艳), Yuan Huang(黄元), Feng-Feng Zhang(张丰丰), Feng Yang(杨峰), Qin-Jun Peng(彭钦军), Shi-Liang Li(李世亮), Huai-Xin Yang(杨槐馨), Jian-Qi Li(李建奇), Zu-Yan Xu(许祖彦), Xing-Jiang Zhou(周兴江)
Chin. Phys. B, 2019, 28 (7): 077403 doi: 10.1088/1674-1056/28/7/077403
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High-quality Bi2-xPbxSr2CaCu2O8+δ (Bi2212) single crystals have been successfully grown by the traveling solvent floating zone technique with a wide range of Pb substitution (x=0-0.8). The samples are characterized by transmission electron microscope (TEM) and measured by high resolution laser-based angle-resolved photoemission spectroscopy (ARPES) with different photon energies. A systematic evolution of the electronic structure and superstructure with Pb substitution has been revealed for the first time. The superstructure shows a significant change with Pb substitution and the incommensurate modulation vector (Q) decreases with increasing Pb substitution. In the meantime, the superstructure intensity from ARPES measurements also decreases dramatically with increasing Pb concentration. The superstructure in Bi2212 can be effectively suppressed by Pb substitution and it nearly disappears with a Pb substitution of x=0.8. We also find that the superstructure bands in ARPES measurements depend sensitively on the photon energy of lasers used; they can become even stronger than the main band when using a laser photon energy of 10.897 eV. These results provide important information on the origin of the incommensurate superstructure and its control and suppression in bismuth-based high temperature superconductors.

A simple rule for finding Dirac cones in bilayered perovskites Hot!

Xuejiao Chen(陈雪娇), Lei Liu(刘雷), Dezhen Shen(申德振)
Chin. Phys. B, 2019, 28 (7): 077106 doi: 10.1088/1674-1056/28/7/077106
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A simple rule for finding Dirac cone electronic states in solids is proposed, which is neglecting those lattice atoms inert to particular electronic bands, and pursuing the two-dimensional (2D) graphene-like quasi-atom lattices with s- and p-bindings by considering the equivalent atom groups in the unit cell as quasi-atoms. Taking CsPbBr3 and Cs3Bi2Br9 bilayers as examples, we prove the effectiveness and generality of this rule with the density functional theory (DFT) calculations. We demonstrate that both bilayers have Dirac cones around the Fermi level and reveal that their corresponding Fermi velocities can reach as high as~0.2×106 m/s. This makes these new 2D layered materials very promising in making new ultra-fast ionic electronic devices.

Fabrication of large-scale graphene/2D-germanium heterostructure by intercalation Hot!

Hui Guo(郭辉), Xueyan Wang(王雪艳), De-Liang Bao(包德亮), Hong-Liang Lu(路红亮), Yu-Yang Zhang(张余洋), Geng Li(李更), Ye-Liang Wang(王业亮), Shi-Xuan Du(杜世萱), Hong-Jun Gao(高鸿钧)
Chin. Phys. B, 2019, 28 (7): 078103 doi: 10.1088/1674-1056/28/7/078103
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We report a large-scale, high-quality heterostructure composed of vertically-stacked graphene and two-dimensional (2D) germanium. The heterostructure is constructed by the intercalation-assisted technique. We first synthesize large-scale, single-crystalline graphene on Ir(111) surface and then intercalate germanium at the interface of graphene and Ir(111). The intercalated germanium forms a well-defined 2D layer with a 2×2 superstructure with respect to Ir(111). Theoretical calculations demonstrate that the 2D germanium has a double-layer structure. Raman characterizations show that the 2D germanium effectively weakens the interaction between graphene and Ir substrate, making graphene more like the intrinsic one. Further experiments of low-energy electron diffraction, scanning tunneling microscopy, and x-ray photoelectron spectroscopy (XPS) confirm the formation of large-scale and high-quality graphene/2D-germanium vertical heterostructure. The integration of graphene with a traditional 2D semiconductor provides a platform to explore new physical phenomena in the future.

Possible nodeless s±-wave superconductivity intwisted bilayer graphene Hot!

Zhe Liu(刘哲), Yu Li(李宇), Yi-Feng Yang(杨义峰)
Chin. Phys. B, 2019, 28 (7): 077103 doi: 10.1088/1674-1056/28/7/077103
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The recent discovery of superconductivity in the twisted bilayer graphene has stimulated numerous theoretical proposals concerning its exact gap symmetry. Among them, the d+ id or p+ ip-wave was believed to be the most plausible solution. Here, considering that the superconductivity emerges near a correlated insulating state and may be induced by antiferromagnetic spin fluctuations, we apply the strong-coupling Eliashberg theory with both inter- and intraband quantum critical pairing interactions and discuss the possible gap symmetry in an effective low-energy four-orbital model. Our calculations reveal a nodeless s±-wave as the most probable candidate for the superconducting gap symmetry in the experimentally relevant parameter range. This solution is distinctly different from previous theoretical proposals. It highlights the multi-gap nature of the superconductivity and puts the twisted bilayer graphene in the same class as the iron-pnictide, electron-doped cuprate, and some heavy fermion superconductors.

Global phase diagram of a spin-orbit-coupled Kondo lattice model on the honeycomb lattice Hot!

Xin Li(李欣), Rong Yu(俞榕), Qimiao Si
Chin. Phys. B, 2019, 28 (7): 077102 doi: 10.1088/1674-1056/28/7/077102
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Motivated by the growing interest in the novel quantum phases in materials with strong electron correlations and spin-orbit coupling, we study the interplay among the spin-orbit coupling, Kondo interaction, and magnetic frustration of a Kondo lattice model on a two-dimensional honeycomb lattice. We calculate the renormalized electronic structure and correlation functions at the saddle point based on a fermionic representation of the spin operators. We find a global phase diagram of the model at half-filling, which contains a variety of phases due to the competing interactions. In addition to a Kondo insulator, there is a topological insulator with valence bond solid correlations in the spin sector, and two antiferromagnetic phases. Due to the competition between the spin-orbit coupling and Kondo interaction, the direction of the magnetic moments in the antiferromagnetic phases can be either within or perpendicular to the lattice plane. The latter antiferromagnetic state is topologically nontrivial for moderate and strong spin-orbit couplings.

Hard carbons derived from pine nut shells as anode materials for Na-ion batteries Hot!

Hao Guo(郭浩), Kai Sun(孙凯), Yaxiang Lu(陆雅翔), Hongliang Wang(王洪亮), Xiaobai Ma(马小柏), Zhengyao Li(李正耀), Yong-Sheng Hu(胡勇胜), Dongfeng Chen(陈东风)
Chin. Phys. B, 2019, 28 (6): 068203 doi: 10.1088/1674-1056/28/6/068203
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Hard carbons as promising anode materials for Na-ion batteries (NIBs) have captured extensive attention because of their low operation voltage, easy synthesis process, and competitive specific capacity. However, there are still several disadvantages, such as high cost and low initial coulombic efficiency, which limit their large-scale commercial applications. Herein, pine nut shells (PNSs), a low-cost biomass waste, are used as precursors to prepare hard carbon materials. Via a series of washing and heat treatment procedures, a pine nut shell hard carbon (PNSHC)-1400 sample has been obtained and delivers a reversible capacity of around 300 mAh/g, a high initial coulombic efficiency of 84%, and good cycling performance. These excellent Na storage properties indicate that PNSHC is one of the most promising candidates of hard carbon anodes for NIBs.

Improved electrochemical performance of Li(Ni0.6Co0.2Mn0.2)O2 at high charging cut-off voltage with Li1.4Al0.4Ti1.6(PO4)3 surface coating Hot!

Yi Wang(王怡), Bo-Nan Liu(刘柏男), Ge Zhou(周格), Kai-Hui Nie(聂凯会), Jie-Nan Zhang(张杰男), Xi-Qian Yu(禹习谦), Hong Li(李泓)
Chin. Phys. B, 2019, 28 (6): 068202 doi: 10.1088/1674-1056/28/6/068202
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Li(Ni0.6Co0.2Mn0.2)O2 has been surface-modified by the lithium-ion conductor Li1.4Al0.4Ti1.6(PO4)3 via a facile mechanical fusion method. The annealing temperature during coating process shows a strong impact on the surface morphology and chemical composition of Li(Ni0.6Co0.2Mn0.2)O2. The 600-℃ annealed material exhibits the best cyclic stability at high charging cut-off voltage of 4.5 V (versus Li+/Li) with the capacity retention of 90.9% after 100 cycles, which is much higher than that of bare material (79%). Moreover, the rate capability and thermal stability are also improved by Li1.4Al0.4Ti1.6(PO4)3 coating. The enhanced performance can be attributed to the improved stability of interface between Li(Ni0.6Co0.2Mn0.2)O2 and electrolyte by Li1.4Al0.4Ti1.6(PO4)3 modification. The results of this work provide a possible method to design reliable cathode materials to achieve high energy density and long cycle life.

Direct deposition of graphene nanowalls on ceramic powders for the fabrication of a ceramic matrix composite Hot!

Hai-Tao Zhou(周海涛), Da-Bo Liu(刘大博), Fei Luo(罗飞), Ye Tian(田野), Dong-Sheng Chen(陈冬生), Bing-Wei Luo(罗炳威), Zhang Zhou(周璋), Cheng-Min Shen(申承民)
Chin. Phys. B, 2019, 28 (6): 068102 doi: 10.1088/1674-1056/28/6/068102
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Uniform mixing of ceramic powder and graphene is of great importance for producing ceramic matrix composite. In this study, graphene nanowalls (GNWs) are directly deposited on the surface of Al2O3 and Si3N4 powders using chemical vapor deposition system to realize the uniform mixing. The morphology and the initial stage of the growth process are investigated. It is found that the graphitic base layer is initially formed parallel to the powder surface and is followed by the growth of graphene nanowalls perpendicular to the surface. Moreover, the lateral length of the graphene sheet could be well controlled by tuning the growth temperature. GNWs/Al2O3 powder is consolidated by using sparking plasma sintering method and several physical properties are measured. Owing to the addition of GNWs, the electrical conductivity of the bulk alumina is significantly increased.

Crystal structures and sign reversal Hall resistivities in iron-based superconductors Lix(C3H10N2)0.32FeSe (0.15 < x < 0.4) Hot!

Rui-Jin Sun(孙瑞锦), Shi-Feng Jin(金士锋), Jun Deng(邓俊), Mu-Nan Hao(郝木难), Lin-Lin Zhao(赵琳琳), Xiao Fan(范晓), Xiao-Ning Sun(孙晓宁), Jian-Gang Guo(郭建刚), Lin Gu(谷林)
Chin. Phys. B, 2019, 28 (6): 067401 doi: 10.1088/1674-1056/28/6/067401
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Heavy electron-doped FeSe-derived materials have attracted attention due to their uncommon electronic structures with only ‘electron pockets’, and they are different from other iron-based superconductors. Here, we report the crystal structures, superconductivities and normal state properties of two new Li-doped FeSe-based materials, i.e., Li0.15(C3H10N2)0.32FeSe (P-4) and Lix(C3H10N2)0.32FeSe (P4/nmm, 0.25 < x < 0.4) with superconducting transition temperatures ranging from 40 K to 46 K. The determined crystal structures reveal a coupling between Li concentration and the orientation of 1,3-diaminopropane molecules within the largely expanded FeSe layers. Superconducting fluctuations appear in the resistivity of the two superconductors and are fitted in terms of the quasi two-dimensional (2D) Lawrence-Doniach model. The existence of a crossing point and scaling behavior in the T-dependence of diamagnetic response also suggests that the two superconductors belong to the quasi-2D system. Interestingly, with the increase of temperature, a sign of Hall coefficient (RH) reversing from negative to positive is observed at~185 K in both phases, suggesting that ‘hole pockets’ emerge in these electron-doped FeSe materials. First principle calculations indicate that the increase in FeSe layer distance will lift up a ‘hole band’ associated with dx2-y2 character and increase the hole carriers. Our findings suggest that the increase in two dimensionalities may lead to the sign-reversal Hall resistivity in Lix(C3H10N2)0.32FeSe at high temperature.

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