Jiuxing Zhang

Hefei University of Technology, Luchow, Anhui Sheng, China

Are you Jiuxing Zhang?

Claim your profile

Publications (89)195.4 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The Mg2Si-based materials have been regarded as the promising and environment-friendly thermoelectric materials at the middle temperature. In this paper, the n-type Mg2(Si0.4Sn0.6)Sbx (0≤x≤0.02) solid solutions were successfully obtained by twice mechanical alloying (MA) and spark plasma sintering (SPS) process, namely the method twice MA+SPS. This work revealed that the dimensionless figure of merit ZT was significantly enhanced due to the nanophase uniformly dispersed in the fine-grained and the increase of the grain boundaries reducing the lattice thermal conductivities. Meanwhile, the nanostructuring and Sb-doping improved electrical performance for Mg2(Si0.4Sn0.6)Sbx (0≤x≤0.02) samples. The highest ZT value up to 1.40 at 673K was obtained for Mg2(Si0.4Sn0.6)Sb0.018 sample.
    No preview · Article · Feb 2016 · Journal of Alloys and Compounds
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: (Nd1−xCex)30Fe69B (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) alloys were prepared by inducting melting, and the effect of substitution of Ce for Nd on their microstructure and intrinsic magnetic properties were investigated. With the increase of Ce content, Curie temperature (Tc) decreases from 582.4 to 504.8 K, saturation magnetization (Ms) decreases from 15.88 to 12.71 kGs, and anisotropy field (HA) decreases from 67.4 to 52.7 kOe. However, the reductions of the intrinsic magnetic properties are relatively gentle, and they still have potential to be prepared as permanent magnets. Moreover, further microstructure observations show that Ce is tending to diffuse into the Nd-rich grain boundary phase instead of main phase during the substitute process. Such aggregation behavior is beneficial to fabricate Ce containing magnet with high Ms.
    Full-text · Article · Nov 2015 · Journal of Magnetism and Magnetic Materials
  • Dongtao Zhang · Xiaokun Yuan · Ming Yue · Qiang Ma · Jie Zhu · Jiuxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: By virtue of the electron backscattered diffraction approach and the two-dimensional five parameter analysis method, the orientation texture of the crystallographic habit planes in a hot deformed PrCo5 bulk permanent magnet is investigated. The results show that the orientations of habit planes are textured, and these orientation textures are heterogeneous at different locations in the magnet. By interrogating the idealized hexagonal polygon to represent the habit plane orientation texture, the average three-dimensional shapes of magnetic crystals at different locations are described, which could benefit the determining of local magnetic characteristics by referring to the relative lengths of easy and hard axes in the polygon. The study therefore suggests a new understanding of the pathway to evaluate the crystallographic orientation dependent performances. This journal is
    No preview · Article · Oct 2015 · RSC Advances
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: (Nd1-xLax)30Fe69B (x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) alloys were prepared by inducting melting, and the effect of substitution of La for Nd on their microstructure and intrinsic magnetic properties were investigated. With the increase of La content, Curie temperature (Tc) decreased from 582.4 to 557.4 K, saturation magnetization (Ms) decreased from 1.59 to 1.37 T, and anisotropy field (HA) decreased from 5394 to 3911 kA/m. However, the reductions of the intrinsic magnetic properties were relatively gentle as La content increased, which meant that the intrinsic magnetic properties still had the potential to fabricate permanent magnets. Moreover, further microstructure observations showed that La tended to diffuse into the Nd-rich grain boundary phase instead of main phase during the substitute process. Such aggregation behavior was beneficial to fabricating La containing magnet with high Ms.
    Full-text · Article · Sep 2015 · Journal of Rare Earths
  • Source
    Zhi Li · Haibin Su · Xinyu Yang · Jiuxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: We studied the electronic structures of antiferromagnetic (AFM) GdBiPt with propagating vectors Q1 - =(0,0,π) (A-type) and Q2 - =(π,π,π) (G-type) by performing first-principles calculation based on density-functional theory with modified Becke and Johnson local-density approximation potentials plus Hubbard U (MBJLDA+U). With the total energy calculation, the G-type AFM spin-ordered state is relatively more stable than the A-type AFM spin-ordered state, although the difference in total energy is minute. Our band-structure calculation predicts that the A-type AFM state is topologically nontrivial due to a single s-character band inversion at the Γ point, which is similar to the band inversions in half-Heusler topological insulator candidates and bulk HgTe semiconductors, while the G-type AFM state is topologically trivial due to the absence of s/p band inversion. With a realistic tight-binding model calculation with 20 bands coupled to an AFM Zeeman field, GdBiPt with A-type AFM spin order presents a metallic surface state on the terminations with AFM aligned Gd ions, and this surface state is independent of the strength of the AFM Zeeman field, i.e., this surface state will be preserved in a nonmagnetic case. Upon terminating the ferromagnetic spin-aligned Gd ions, the surface state is dependent on the strength of the Zeeman field, and the metallic surface can recover when the Zeeman field approaches zero.
    Full-text · Article · Jun 2015 · Physical Review B
  • [Show abstract] [Hide abstract]
    ABSTRACT: The electron backscattered diffraction approach and five parameter analysis method are used to investigate the orientation textures of boundary planes in a (La0.67Nd0.33)B6 polycrystalline bulk prepared by spark plasma sintering. While the entire boundaries overall favour the {001} orientation, orientation textures of various boundary planes are not homogeneous. If divided by the boundary type, the LaB6/LaB6 grain boundary planes favour the {001} orientation, the NdB6/NdB6 grain boundary plane orientation approaches the {011} position, and the LaB6/NdB6 phase boundary planes favour the {011} orientation. If divided by the misorientation angle, boundaries with misorientation angle lower than 10° favour the {011} orientation, and boundaries with misorientation angle higher than 10° favour the {001} orientation. Possible origins of the anisotropic distribution of boundary planes are analyzed. Potential effects of the anisotropy in boundary plane distributions on the electron emissivity are also suggested.
    No preview · Article · Apr 2015 · CrystEngComm
  • Weixiao Ji · Weiqiang Liu · Ming Yue · Dongtao Zhang · Jiuxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: The waste VCM magnets were disassembled from hard disk. After removing the coating of nickel by electrochemical method, the waste VCM magnets were recycled by grain boundary diffusion with DyH3 nano-particles. Compared to that of the original magnet, the coercivity of recycled magnets increases by 11.81 kOe, while the remanence keeps almost invariant. Investigation shows that Dy is preferentially enriched as (Nd,Dy)2Fe14B phase in the surface region of the Nd2Fe14B matrix grains indicated by the remarkable enhancement of the magneto-crystalline anisotropy field of the magnet. As a result, the magnet diffused with a small amount of DyH3 nano-particles possesses enhanced coercivity without remarkably sacrificing its magnetization.
    No preview · Article · Mar 2015 · Physica B Condensed Matter
  • [Show abstract] [Hide abstract]
    ABSTRACT: Structure and magnetic properties were studied for bulk nanocrystalline isotropic and anisotropic NdFeB permanent magnets prepared by spark plasma sintering (SPS). The neck formation among the NdFeB powders, which was governed by sintering conditions in the SPS process, has a substantial influence on the microstructure and subsequent magnetic properties of the magnets. By tuning the current pulse ratio of power-on to power-off time during sintering from 12:2 to 2:2, we successfully reduced the thickness of the surface diffusion layer of the NdFeB particles in both hot-pressed and hot-deformed magnets. As a result, the maximum energy product of the isotropic and anisotropic magnets increases by 27 and 9, respectively.
    No preview · Article · Jan 2015 · IEEE Magnetics Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report high-resolution angle-resolved photoelectron spectroscopy (ARPES) results on the (001) cleavage surface of YbB6, a rare-earth compound that has been recently predicted to host surface electronic states with topological character. We observe two types of well-resolved metallic states, whose Fermi contours encircle the time-reversal invariant momenta of the YbB6(001) surface Brillouin zone, and whose full E(k) dispersion relation can be measured wholly unmasked by states from the rest of the electronic structure. Although the two-dimensional character of these metallic states is confirmed by their lack of out-of-plane dispersion, our work reveals two aspects which were not observed in previous experiments. First, these states do not resemble two branches of opposite, linear velocity that cross at a Dirac point, but rather straightforward parabolas that terminate to high binding energy with a clear band bottom. Secondly, these states are sensitive to time-dependent changes of the YbB6 surface under ultrahigh-vacuum conditions. Adding the fact that these data from cleaved YbB6 surfaces also display spatial variations in the electronic structure, it appears there is little in common between the theoretical expectations for an idealized YbB6(001) crystal truncation on the one hand, and these ARPES data from real cleavage surfaces on the other.
    No preview · Article · Dec 2014 · Physical Review B
  • Source
    Ming Yue · Hongguo Zhang · Danmin Liu · Jiuxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: As one of magnetic refrigerants with giant magnetocaloric effect (GMCE), MnFePGe-based compounds had drawn tremendous attention due to their many advantages for practical applications. In this paper, correlations among preparation conditions, magnetic and crystal structures, and magnetocaloric effects (MCE) of the MnFePGe-based compounds are reviewed. Structure evolution and phase transformation in the compounds as a function of temperature, pressure, and magnetic field were reported. Influences of preparation conditions to the chemical composition and microstructure homogeneity of the compounds, which play key role to the MCE and thermal hysteresis of the compounds, were introduced. Based upon these experimental results, a new method to evaluate MCE of the compounds via DSC measurements was proposed. Moreover, the origin of virgin effect of the MnFePGe-based compounds was discussed.
    Preview · Article · Nov 2014 · Chinese Physics B
  • Ran Zhao · Fu Guo · Yutian Shu · Xin Zhang · Qingmei Lu · Jiuxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Since the nanostructure was introduced to modify thermoelectric properties in 1993, many efforts have been devoted to fabricate nanostructures and investigate the electrical and thermal transports in nanostructured materials. Compared with low-dimensional materials, nanocomposites not only exhibit nanofeatures but also can be fabricated in large quantities and compatible with practical thermoelectric devices in scale and shape. This article reviews the background of nanocomposites, then the Mg-2(Si0.4Sn0.6)Bi-x solid solutions. High-manganese silicides with MnSi (HMS-MnSi), and In4-xGdxSe3 compounds are selected as examples to illustrate the combination effect of nanostructure and dopants on thermoelectric properties. In situ nanostructures successfully formed during the rapid cooling and spark-plasma sintering processing and elemental doping were achieved via melting processing. Electrical conductivities were enhanced as a result of the increased carrier concentration or carrier mobility by elemental doping. Meanwhile, thermal conductivities decreased as a result of the strong phonon scattering intensified by nanostructures. The ZTs for the specimens with optimal doping ratio were enhanced in these three types of thermoelectric materials.
    No preview · Article · Nov 2014 · JOM: the journal of the Minerals, Metals & Materials Society
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report high resolution Angle Resolved PhotoElectron Spectroscopy (ARPES) results on the (001) cleavage surface of YbB$_{6}$, a rare-earth compound which has been recently predicted to host surface electronic states with topological character. We observe two types of well-resolved metallic states, whose Fermi contours encircle the time-reversal invariant momenta of the YbB$_{6}$(001) surface Brillouin zone, and whose full (E,k)-dispersion relation is wholly unmasked by states from the rest of the electronic structure. Although the surface character of these metallic states is confirmed by their lack of out-of-plane dispersion, two new aspects are revealed in these experiments. Firstly, the surface states are sensitive to time-dependent changes of the YbB$_{6}$ surface under ultrahigh vacuum conditions. Secondly, these surface states also do not resemble two branches of opposite velocity that cross at a Dirac point, but rather straightforward parabolas which terminate to high binding energy with a clear band bottom. Adding the fact that these data from cleaved YbB$_{6}$ surfaces also display spatial variations in the electronic structure, it appears there is little in common between the theoretical expectations for an idealized YbB$_{6}$(001) crystal truncation on the one hand, and these ARPES data from real cleavage surfaces on the other.
    Full-text · Article · Sep 2014
  • Xin Zhang · Chaolong Liang · Jiuxing Zhang · Wei Liu

    No preview · Conference Paper · Jun 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: The single-phase n-type Mg2(Si0.4−xSbxSn0.6) (0≤x≤0.025) solid solutions were prepared by an induction melting and Spark Plasma Sintering method using buck of Magnesium, Silicon, Tin and Antimony. The unique multiple nanostructures of samples containing nanoscale precipitates and mesoscale grains are formed by the non-equilibrium preparing technique, resulting in remarkably decreasing of lattice thermal conductivities, particularly for samples with the nanoscale precipitates having the size of 20–30 nm. Meanwhile, the electrical properties were increased by Sb-doping. The thermoelectric performance of Sb doped samples with the nanostructures are remarkably improved, and the dimensionless figure of ZT for Mg2(Si0.38Sb0.02Sn0.6) sample shows highest value of 1.30 at 773 K, which is very much higher than that of the non-doped sample.
    No preview · Article · May 2014 · Materials Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: Single-phase polycrystalline solid solutions (La1−xSmx)B6 (x = 0, 0.2, 0.4, 0.8, 1) are fabricated by spark plasma sintering (SPS). This study demonstrates a systematic investigation of structure–property relationships in Sm-doped LaB6 ternary rare-earth hexaborides. The microstructure, crystallographic orientation, electrical resistivity, and thermionic emission performance of these compounds are investigated. Analysis of the results indicates that samarium (Sm) doping has a noticeable effect on the structure and performance of lanthanum hexaboride (LaB6). The analytical investigation of the electron backscatter diffraction confirms that (La0.6Sm0.4)B6 exhibits a clear (001) texture that results in a low work function. Work functions are determined by pulsed thermionic diode measurements at 1500–1873 K. The (La0.6Sm0.4)B6 possesses improved thermionic emission properties compared to LaB6. The current density of (La0.6Sm0.4)B6 is 42.4 A cm−2 at 1873 K, which is 17.5% larger than that of LaB6. The values of ΦR for (La0.6Sm0.4)B6 and LaB6 are 1.98 ± 0.03 and 1.67 ± 0.03 eV, respectively. Furthermore, the Sm substitution of lanthanum (La) effectively increases the electrical resistivity. These results reveal that Sm doping lead to significantly enhanced thermionic emission properties of LaB6. The compound (La0.6Sm0.4)B6 appears most promising as a future emitter material.
    No preview · Article · Mar 2014 · Physica Status Solidi (A) Applications and Materials
  • [Show abstract] [Hide abstract]
    ABSTRACT: The electron backscattered diffraction technique was used to identify the orientation textures of both grains and boundary planes in a hot deformed SmCo5 permanent magnet. The results show that the orientations of SmCo5 grains are strongly textured and the {0001} orientations are remarkably preferred. Moreover, grain boundary planes are also textured. Three symmetry equivalents of Σ13a boundaries, namely the 27.796°/[0001] boundary, the 32.204°/[0001] boundary and the 92.204°/[0001] boundary, are favored, and the occurring frequency of Σ13a boundaries is 5 times higher than that of the random boundaries. Potential effects of the orientation textures of grains and boundary planes on the magnets are also proposed.
    No preview · Article · Feb 2014 · CrystEngComm
  • [Show abstract] [Hide abstract]
    ABSTRACT: SmCo6.6Nb0.4 nanoflakes with TbCu7 structure were successfully prepared by surfactant-assisted high energy ball milling (SA-HEBM) with heptane and oleic acid as milling medium. The microstructure, crystal structure and magnetic properties were studied by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer, respectively. The effects of ball milling time on the c-axis crystallographic alignment and coercivity of the nanoflakes were systematically investigated. The research showed that the nanoflakes had an average thickness of 100 nm, an average diameter of 1 μm, with an aspect ratio as high as 100. As the ball milling time increased from 2 to 8 h, the reflection peaks intensity ratio I(002)/I(101), which indicated the degree of c-axis crystal texture of the SmCo6.6Nb0.4 phase, increased first, reached a peak at 4 h, and then decreased. Meanwhile, the coercivity of the nanoflakes also increased first, reached a peak at 13.86 kOe for 4 h, and then decreased.
    No preview · Article · Oct 2013 · Journal of Rare Earths
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rare earth Pr doped Ca1−xPrxMnO3 (x=0, 0.06, 0.08, 0.1, 0.12, and 0.14) compound bulk samples were prepared to study the effect of Pr doping on thermoelectric transport properties of CaMnO3 compound system. The doped samples exhibited single phase composition within the experimental doping range, with condensed bulk microstructure and small porosities. The electrical resistivity was remarkably reduced for doped samples, on account of the enhanced carrier concentration; the absolute value of Seebeck coefficient was deteriorated mainly due to enhanced electron carrier concentration. The electrical performances of the doped samples reflected by resistivity and Seebeck coefficient fluctuations were optimistically tuned, with an optimized power factor value of 0.342 mW/(m·K2) at 873 K for x=0.08 sample, which was very much higher comparing with that of the un-doped sample. The lattice thermal conduction was really confined, leading to distinctly repressed total thermal conductivity. The thermoelectric performance was noticeably improved by Pr doping and the dimensionless figure of merit ZT for the Ca0.92Pr0.08MnO3 compound was favorably optimized with the maximum value 0.16 at 873 K.
    No preview · Article · Sep 2013 · Journal of Rare Earths
  • Xin Zhang · Hongliang Liu · Qingmei Lu · Jiuxing Zhang · Feipeng Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: n-type Mg2(Si0.4Sn0.6)Bix (0 ≤ x ≤ 0.04) solid solutions with minute amounts of Bi were prepared by induction melting, melt spinning (MS), and spark plasma sintering (SPS) method, namely the non-equilibrium technique MS-SPS, using bulks of Mg, Si, Sn, Bi as raw materials; the phase components, microstructures as well as the thermoelectric properties were systematically investigated. The multiple localized nanostructures within the matrix containing nanoscale precipitates and mesoscale grains were formed, resulting in remarkably decreasing of lattice thermal conductivities, particularly for samples with the nanoscale precipitates having the size of 10–20 nm. Meanwhile, the electrical resistivity was reduced and the Seebeck coefficient was increased by Bi-doping, causing improved electrical performance for the Mg2(Si0.4Sn0.6)Bix (0 ≤ x ≤ 0.04) compounds. The dimensionless figure of merit ZT was significantly improved and the maximum value reaches 1.20 at 573 K for the Mg2(Si0.4Sn0.6)Bi0.03 sample, greatly higher than that of the non-doped samples.
    No preview · Article · Aug 2013 · Applied Physics Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Ba-, La- and Ag-doped polycrystalline Ca2.9M0.1Co4O9 (M=Ca, Ba, La, Ag) thermoelectric bulk samples were prepared via citrate acid sol-gel synthesis method followed by spark plasma sintering technique. The bulk samples were characterized and analyzed with regard to their phase compositions, grain orientations as well as microstructures. The high temperature thermoelectric transport properties of the bulk samples were studied in detail. All bulk samples were found to be single-phased with modified body texture. The electrical resistivity was modulated as a result of carrier concentration modification, however the carrier transport process was not influenced; the Seebeck coefficient was deteriorated simultaneously. The total thermal conductivity was remarkably reduced, on account of the decreasing of phonon thermal conductivity. The thermoelectric properties of the Ba-, La-, and Ag-doped bulk samples were optimized, and the Ba-doped Ca2.9Ba0.1Co4O9 system was found to have the highest dimensionless figure of merit ZT 0.20 at 973 K, which was remarkably higher than that of the un-doped sample.
    No preview · Article · Aug 2013 · Journal of Rare Earths

Publication Stats

951 Citations
195.40 Total Impact Points

Institutions

  • 2014-2015
    • Hefei University of Technology
      • School of Materials Science and Engineering
      Luchow, Anhui Sheng, China
  • 2003-2015
    • Beijing University of Technology
      Peping, Beijing, China
  • 2008
    • University of Science and Technology, Beijing
      • School of Materials Science and Engineering
      Peping, Beijing, China