42 results on '"Zhong, Z."'
Search Results
2. Permeability dependence of the effective magnetostriction of magnetostrictive composites.
- Author
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Wan, Y. P., Zhong, Z., and Fang, D. N.
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PERMEABILITY , *MAGNETOSTRICTIVE transducers , *MAGNETOSTRICTION , *RARE earth metals , *NICKEL , *ENERGY dissipation - Abstract
A model is presented in this article to investigate the dependence of effective magnetostriction of the magnetostrictive composites on the parameters of components including the elastic modulus, permeability, and volume fraction, etc. Concentrating on the two-component magnetostrictive composites and choosing the two components to be general magnetostrictive materials, this model yields, analytically, the effective magnetostriction of composites by means of the method of complex potential. In terms of the analysis of this model, the magnetostrictive composites can be roughly divided into two kinds. One kind is that the matrix material is nonmagnetic or a material with very low magnetostriction, in which the effective magnetostriction is independent of the permeability of components. Another kind is the case in which the two components have close magnetostriction, and the effective magnetostriction of the composites generally depends on the elastic and the magnetic parameters of both components and the volume fraction. Unlike the first kind of composite, in a certain range, effective magnetostriction of this kind of composite can be improved by increasing the permeability of matrix. In addition, dependence of the effective magnetostriction on the other parameters of the components has also been discussed systematically. To evaluate the accuracy of this model, comparisons are made between the theoretical values and the experimental results published in the literature, which indicate that predictions of this model agree qualitatively with the experimental data. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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3. Primary photoluminescence in as-neutron (electron) -irradiated n-type 6H-SiC.
- Author
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Zhong, Z. Q., Wu, D. X., Gong, M., Wang, O., Shi, S. L., Xu, S. J., Chen, X. D., Ling, C. C., Fung, S., Beling, C. D., Brauer, G., Anwand, W., and Skorupa, W.
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PHOTOLUMINESCENCE , *IRRADIATION , *NEUTRONS , *ELECTRONS , *PARTICLES (Nuclear physics) , *SPECTRUM analysis - Abstract
Low-temperature photoluminescence spectroscopy has revealed a series of features labeled S1, S2, S3 in n-type 6H-SiC after neutron and electron irradiation. Thermal annealing studies showed that the defects S1, S2, S3 disappeared at 500 °C. However, the well-known D1 center was only detected for annealing temperatures over 700 °C. This experimental observation not only indicated that the defects S1, S2, S3 were a set of primary defects and the D1 center was a kind of secondary defect, but also showed that the D1 center and the E1, E2 observed using deep level transient spectroscopy might not be the same type of defects arising from the same physical origin. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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4. Texture evolution in nanocrystalline Cu under shock compression.
- Author
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Hu, S. C., Huang, J. W., Zhong, Z. Y., Zhang, Y. Y., Cai, Y., and Luo, S. N.
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TEXTURE mapping , *CRYSTAL texture , *EULER angles , *DISTRIBUTION (Probability theory) , *SHOCK waves - Abstract
We investigate with large-scale molecular dynamics simulations texture evolution in nanocrystalline Cu under planar shock wave loading. Five representative initial textures are explored under varying impact strengths. On the basis of Euler angles, we perform orientation mapping and texture analysis, including orientation distribution functions, pole figures, and inverse pole figures. Shock compression induces a weak but apparent ⟨ 110 ⟩ textures in nanocrystalline Cu initially with no texture, and a ⟨ 100 ⟩ fiber texture, and an incomplete weak ⟨ 110 ⟩ texture in nanocrystalline Cu initially with a { 100 } ⟨ 100 ⟩ recrystallization texture; such texture changes can be attributed to deformation twinning and dislocation slip and traced back to grains initially with ⟨ 100 ⟩. A ⟨ 100 ⟩ texture and a { 100 } ⟨ 100 ⟩ cube texture component are induced via twinning in nanocrystalline Cu initially with the ⟨ 111 ⟩ and β fiber textures, respectively, and can be traced back to grains initially with ⟨ 111 ⟩. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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5. Thermal deformation measurement of electronic packages using the atomic force microscope scanning moiré technique.
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Lu, Y. G., Zhong, Z. W., Yu, J., Xie, H. M., Ngoi, B. K. A., Chai, G. B., and Asundi, A.
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ATOMIC force microscopy , *DIFFRACTION gratings , *ELECTRONIC packaging , *MOIRE method - Abstract
In this article, the feasibility of atomic force microscope (AFM) scanning moiré on a cross-line diffraction grating has been studied. The AFM scanning moiré technique has been applied to measure the thermal deformation of electronic packages successfully. This technique is convenient to perform the mismatch method, also it could obtain a higher resolution than any other moiré method. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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6. Width dependent edge distribution of graphene nanoribbons unzipped from multiwall carbon nanotubes.
- Author
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Zhong, Z. F., Shen, H. L., Cao, R. X., Sun, L., Li, K. P., Wang, X. R., and Ding, H. F.
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GRAPHENE , *NANORIBBONS , *MULTIWALLED carbon nanotubes , *SCANNING tunneling microscopy , *LATTICE theory - Abstract
We present the width dependent study of edge distribution of graphene nanoribbons unzipped from multi-wall nanotubes. The partial unzipping of the carbon nanotubes yields a mixture of carbon nanotubes and nanoribbons. Comparing atomic resolution images of scanning tunneling microscopy with the lattice of graphene, the edge structures of nanoribbons are identified. Below 10 nm, the edges are closer to armchair type. Above 20 nm, the ribbons prefer to have edges close to zigzag type. In between, a more random distribution of the edges is found. The findings are of potential usages for the edge control in graphene nanoribbon based applications. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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7. Periodic pillar structures by Si etching of multilayer GeSi/Si islands.
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Zhong, Z., Katsaros, G., Stoffel, M., Costantini, G., Kern, K., Schmidt, O. G., Jin-Phillipp, N. Y., and Bauer, G.
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SILICON , *ELECTRIC properties of silicon , *ETCHING , *CRYSTAL etching , *SEMICONDUCTOR etching , *VIA (Electricity) - Abstract
Laterally aligned multilayer GeSi/Si islands grown on a patterned Si (001) substrate are disclosed by selective etching of Si in a KOH solution. This procedure allows us to visualize the vertical alignment of the islands in a three-dimensional perspective. Our technique reveals that partly coalesced double islands in the initial layer do not merge together, but instead gradually reproduce into well-separated double islands in upper layers. We attribute this effect to very thin spacer layers, which efficiently transfer the strain modulation of each island through the spacer layer to the surface. The etching rate of Si is reduced in tensile strained regions, which helps to preserve sufficient Si between the stacked islands to form a periodic array of freestanding and vertically modulated heterostructure pillars. [ABSTRACT FROM AUTHOR]
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- 2005
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8. Increase of island density via formation of secondary ordered islands on pit-patterned Si (001) substrates.
- Author
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Zhong, Z., Schmidt, O. G., and Bauer, G.
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GERMANIUM crystals , *CRYSTAL growth , *CRYSTALLIZATION , *EPITAXY ,ELECTRIC properties of germanium crystals ,MAGNETIC properties of germanium crystals - Abstract
Site-controlled groups of Ge islands are grown on pit-patterned Si (001) substrates. By varying the deposited amount of Ge, we find that the growth starts with the formation of a single island at the pit bottom and then proceeds to the formation of a highly symmetric Ge island group around the pit top. A bimodal size distribution of dome-shaped islands at the bottom and at the top corners of the pits is observed. A growth mechanism is proposed to qualitatively explain these phenomena. Our experiments help to promote a further understanding of Ge island growth on patterned substrates. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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9. Phase transformations in hypereutectic MgO-Y2O3 nanocomposites at 5.5 GPa.
- Author
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Şavklıyıldız, İ., Akdoğan, E. K., Zhong, Z., Wang, L., Weidner, D., Vaughan, M., Croft, M. C., and Tsakalakos, T.
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NANOCOMPOSITE materials , *HIGH temperatures , *SYNCHROTRONS , *MAGNESIUM oxide , *YTTRIUM - Abstract
Hypereutectic 0.8MgO-0.2Y2O3 nanocomposites were studied using high pressure and high temperature in situ synchrotron energy dispersive x-ray diffractometry at 5.5 GPa and 1273 K. Polymorphic transformations in the Y2O3 phase, which resulted in a quadruple phase equilibria among cubic, hexagonal, and monoclinic phases with cubic MgO, were observed at 298 K under 5.5 GPa-a pressure much smaller than the pressures at which polymorphic transitions in macroscopic Y2O3. Time-resolved diffractometry at (1273 K, 5.5 GPa, 120 min) revealed a 0.87% expansive volumetric lattice strain in MgO, and is attributed to solid solution formation with Y2O3 which is otherwise absent at ambient conditions. The residual MgO unit cell volume expansion is 0.69% at 298 K, which is indicative that yttrium remained in solid solution. The macroscopic shrinkage due to densification at (1273 K, 5.5 GPa, 120 min) is 3.45% by volume. The partial molar volume of Y3+ in the solid solution is smaller than its molar volume in the pure state per thermodynamic considerations. The importance of repulsion among O2- ions in the immediate vicinity of a Mg2+ vacancy as well as misfit strain due to differences in ionic radii upon Y3+ substitution on Mg2+ sites is presented. A self-consistent model and explanation for the observed concomitant occurrence of cubic → monoclinic and cubic → hexagonal polymorphic transitions in Y2O3 and their stabilization at room temperature is proposed. [ABSTRACT FROM AUTHOR]
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- 2013
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10. A study of pressure-shear vertical wave propagation in periodically layered fluid and piezoelectric structure.
- Author
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Zhao, J., Pan, Y., and Zhong, Z.
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SHEAR waves , *THEORY of wave motion , *PRESSURE , *FLUIDS , *PIEZOELECTRICITY - Abstract
In this paper, the pressure (P) and shear vertical (SV) wave propagation in the periodically layered fluid and piezoelectric structure are theoretically studied. A single piezoelectric layer is first analyzed for three scenarios: piezoelectricity-ignored, electrically open, or electrically closed. It is observed that both the Lamb wave dispersion curves and the transmission coefficients are affected by piezoelectricity and electrical boundary conditions under any incident angle. From the analyses of the periodically layered structure, it is further found that the piezoelectricity and the electrical boundary conditions have influence on band gaps for a given incident angle. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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11. Theoretical study of shear horizontal wave propagation in periodically layered piezoelectric structure.
- Author
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Zhao, J., Pan, Y., and Zhong, Z.
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THEORY of wave motion , *PIEZOELECTRIC materials , *PIEZOELECTRICITY , *WAVE equation , *PHYSICS - Abstract
In this paper, the propagation of the shear horizontal wave (SH-wave) in the single piezoelectric layer and periodically layered piezoelectric structure is studied. Both the dispersion equation and transmission coefficients are derived to reveal the wave behavior of the corresponding structures when the piezoelectricity is ignored or the electrical circuit is open and closed. The zero-order mode of the piezoelectricity-ignored single plate is not dispersive and every higher order mode is dispersive with a cut-off frequency. Same features are found for the electrically open and closed cases except that the zero-order mode of the latter case is no more non-dispersive. The pass bands of the piezoelectricity-ignored periodically layered structure appear when the normalized frequency is an even integer under the normal incidence, and new stop bands will appear from the pass bands as the incident angle increases. The same features are observed for the band gaps of the electrically open and closed cases except that the zero-order mode of the latter case is dispersive. The stop bands of the periodic structure will change in a cycle as the geometric ratio increases from zero to one. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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12. Strain field and scattered intensity profiling with energy dispersive x-ray scattering.
- Author
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Croft, M., Zakharchenko, I., Zhong, Z., Gurlak, Y., Hastings, J., Hu, J., Holtz, R., DaSilva, M., and Tsakalakos, T.
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SCATTERING (Physics) , *X-ray spectroscopy - Abstract
Two powerful synchrotron x-ray scattering techniques for residual strain depth-profiling and tomography-like scatter-intensity profiling of materials are presented. The techniques utilize energy dispersive x-ray scattering, from a fixed microvolume, with microscanning of the specimen being used to profile its interior. The tomography-like profiles exploit scattering-cross-section variations, and can be contrast enhanced by separately monitoring scattering from different crystal structures. The strain profiling technique is shown to finely chronicle the internal strain variation over several mm of steel. Detailed strain profiling for a cantilever spring demonstrates the interplay of residual and external stresses in elastic/plastic deformation. Since surface compression, by shot peening, is a classic method to fortify against fatigue failure, the strain profile for a shot-peened, surface-toughened material is determined and discussed in terms of a simple elastic-plastic stress/ strain model. Finally the lattice strains in a WC/Co coated steel composite material are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2002
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13. Texture evolution in nanocrystalline Ta under shock compression.
- Author
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Hu, S. C., Huang, J. W., Feng, Z. D., Zhang, Y. Y., Zhong, Z. Y., Cai, Y., and Luo, S. N.
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TANTALUM , *TEXTURE mapping , *CRYSTAL texture , *MOLECULAR dynamics , *DISTRIBUTION (Probability theory) , *SHOCK waves - Abstract
We present systematic investigation on texture evolution in nanocrystalline Ta under planar shock wave loading at different impact velocities. Seven representative initial textures and two loading directions are studied via large-scale molecular dynamics simulations. Orientation mapping and texture analysis, including orientation distribution functions, pole figures, and inverse pole figures, are performed. Shock compression induces a ⟨ 221 ⟩ texture in nanocrystalline Ta initially with no texture, ⟨ 100 ⟩ fiber texture, { 100 } ⟨ 100 ⟩ texture, and θ + γ rolling texture via twinning, which can be traced back to grains initially with ⟨ 100 ⟩. A ⟨ 100 ⟩ texture is induced via twinning for nanocrystalline Ta initially with no texture, ⟨ 110 ⟩ fiber texture, and α + γ rolling texture and can be traced back to ⟨ 110 ⟩. Dislocation slip and grain boundary sliding lead to the movement of ⟨ 110 ⟩ toward ⟨ 111 ⟩ , and the strengthening of ⟨ 100 ⟩ and ⟨ 111 ⟩ orientation densities. The generation of new textures is observed for most cases. However, no new texture is found in the ⟨ 111 ⟩ fiber texture case for shock loading parallel to the fiber, and a much slower elastic–plastic transition occurs due to the lack of deformation twinning. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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14. The influence of density in ultracold neutral plasma.
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Gao, J. W., Wu, Y., Zhong, Z. P., and Wang, J. G.
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COUPLING constants , *ENERGY level densities , *PLASMA gases , *PLASMA physics , *COLLISIONS (Nuclear physics) - Abstract
We simulate the evolution of ultracold neutral plasmas using molecular dynamics calculations with open boundary conditions. The calculations use 6000 ions and 6000 electrons, respectively, with a quasi-real ion-electron mass ratio of mi=me = 1000. The simulated plasmas have both Gaussian and ordered initial distributions. While disorder-induced heating is absent in the initially ordered distributions, the ions are heated significantly by electron-ion collisions. We show that the value of the strong coupling parameter typically falls below 10 for realistic plasma densities. [ABSTRACT FROM AUTHOR]
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- 2016
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15. Formation of coupled three-dimensional GeSi quantum dot crystals.
- Author
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Ma, Y. J., Zhong, Z., Lv, Q., Zhou, T., Yang, X. J., Fan, Y. L., Wu, Y. Q., Zou, J., and Jiang, Z. M.
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OPTICAL properties of germanium silicide , *QUANTUM dots , *QUANTUM electronics , *PHOTOLUMINESCENCE , *PHONONS - Abstract
Coupled three-dimensional GeSi quantum dot crystals (QDCs) are realized by multilayer growth of quantum dots (QDs) on patterned SOI (001) substrates. Photoluminescence spectra of these QDCs show non-phonon (NP) recombination and its transverse-optical (TO) phonon replica of excitons in QDs. With increasing excitation power, peak energies of both the NP and TO peaks remain nearly constant and the width of the TO peak decreases. These anomalous features of the PL peaks are attributed to miniband formation due to strong coupling of the holes and the emergence of quasioptical phonon modes due to periodic scatters in ordered GeSi QDs. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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16. Intense infrared upconversion luminescence of NaGdF4:Yb/Tm with controlled intensity.
- Author
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Chen, X., Vanacken, J., Han, J., Zhong, Z., Li, L., Han, Y., Liu, Y., and Moshchalkov, V. V.
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NANOPARTICLES , *ENERGY transfer , *RARE earth metals , *LUMINESCENCE , *CRYSTAL field theory - Abstract
Nanoparticles with different core@shell structures (NaGdF4:Yb/Tm@NaLnF4 with Ln=lanthanide) were successfully synthesized for luminescence upconversion from 980 nm to 800 nm. The upconversion luminescence of the core@shell nanoparticles (NaGdF4:Yb/Tm@NaGdF4) has a much stronger infrared emission centered at 800 nm than that of the core-only nanoparticles (NaGdF4:Yb/Tm). This is not only due to the removal of surface defects of the core nanoparticles by the shell, which results in the decrease of the luminescence quenching, but also due to the breaking of the crystal field symmetry around the Tm3+ ion. By replacing the NaGdF4 shell with an NaYF4, the emission could further be enhanced. We suggest that the breaking of the crystal field symmetry plays also in this case a key role for further enhancement of upconversion emission. The importance of this asymmetry was further revealed by investigating the energy transfer between Er3+ ion in the shell and the Tm3+ ion of the core nanoparticle. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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17. Note: Characterization of a high-photon-energy X-ray imager.
- Author
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Storm, M., Eichman, B., Zhong, Z., Theobald, W., Schiebel, P., Mileham, C., Stoeckl, C., Begishev, I. A., Fiksel, G., Stephens, R. B., Freeman, R. R., and Akli, K. U.
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BRAGG gratings , *QUARTZ , *CRYSTALS , *ZIRCONIUM , *LASER research - Abstract
The Bragg angle, rocking curve, and reflection efficiency of a quartz crystal x-ray imager (Miller indices 234) were measured at photon energy of 15.6909 keV, corresponding to the Kα2 line of Zr, using the X15A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory. One flat and three spherically curved samples were tested. The peak reflectivity of the best-performing crystal was determined to be (3.6 ± 0.7) × 10-4 with a rocking-curve full width at half maximum of 0.09°. The Zr Kα2 emission was imaged from a hot Zr plasma generated by a 10-J multiterawatt laser. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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18. Anomalous lattice expansion in yttria stabilized zirconia under simultaneous applied electric and thermal fields: A time-resolved in situ energy dispersive x-ray diffractometry study with an ultrahigh energy synchrotron probe.
- Author
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Akdoğan, E. K., Şavklıyıldız, İ., Biçer, H., Paxton, W., Toksoy, F., Zhong, Z., and Tsakalakos, T.
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YTTRIA stabilized zirconium oxide , *PARTICULATE matter , *LATTICE theory , *SOIL densification , *ELECTRIC fields , *SYNCHROTRONS , *HEATING - Abstract
Nonisothermal densification in 8% yttria doped zirconia (8YSZ) particulate matter of 250 nm median particle size was studied under 215 V/cm dc electric field and 9 °C/min heating rate, using time-resolved in-situ high temperature energy dispersive x-ray diffractometry with a polychromatic 200 keV synchrotron probe. Densification occurred in the 876-905 °C range, which resulted in 97% of the theoretical density. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. The maximum current draw at 905 °C was 3 A, corresponding to instantaneous absorbed power density of 570 W/cm3. Densification of 8YSZ was accompanied by anomalous elastic volume expansions of the unit cell by 0.45% and 2.80% at 847 °C and 905 °C, respectively. The anomalous expansion at 905 °C at which maximum densification was observed is characterized by three stages: (I) linear stage, (II) anomalous stage, and (III) anelastic recovery stage. The densification in stage I (184 s) and II (15 s) was completed in 199 s, while anelastic relaxation in stage III lasted 130 s. The residual strains ([variant_greek_epsilon]) at room temperature, as computed from tetragonal (112) and (211) reflections, are [variant_greek_epsilon](112) = 0.05% and [variant_greek_epsilon](211) = 0.13%, respectively. Time dependence of (211) and (112) peak widths (β) show a decrease with both exhibiting a singularity at 905 °C. An anisotropy in (112) and (211) peak widths of {β(112)/β(211)} = (3:1) magnitude was observed. No phase transformation occurred at 905 °C as verified from diffraction spectra on both sides of the singularity, i.e., the unit cell symmetry remains tetragonal. We attribute the reduction in densification temperature and time to ultrafast ambipolar diffusion of species arising from the superposition of mass fluxes due to Fickian diffusion, thermodiffusion (Soret effect), and electromigration, which in turn are a consequence of a superposition of chemical, temperature, and electrical potential gradients. On the other hand, we propose defect pile-up at particle-particle contacts and subsequent tunneling as a mechanism creating the 'burst-mode' discontinuous densification at the singularities observed at 847 and 905 °C. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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19. Giant exchange bias effect in all-3d-metal Ni38.8Co2.9Mn37.9Ti20.4 thin film.
- Author
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Liu, K., Ma, S. C., Zhang, Z. S., Zhao, X. W., Yang, B., Wang, D. H., Ur Rehman, S., and Zhong, Z. C.
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THIN films , *MAGNETIC relaxation , *MAGNETIC measurements , *EXCHANGE , *METAL clusters - Abstract
In this work, a giant exchange bias field of over 1 kOe, which is uncommon in film systems, is obtained in all-3d-metal Heusler-type Ni38.8Co2.9Mn37.9Ti20.4 thin films. The thermomagnetic curves show an unambiguous noncoincidence between zero-field-cooled and field-cooled protocols, indicating the presence of magnetically inhomogeneous phases in the film in the low temperature range. Magnetic measurements, including magnetic relaxation and magnetic memory effects, demonstrate that the exchange bias should be attributed to the exchange interaction between ferromagnetic clusters and the antiferromagnetic host in the Ni38.8Co2.9Mn37.9Ti20.4 thin film at low temperature. The local Mn-Co-Mn configuration provides the ferromagnetic contribution, which is formed in the antiferromagnetic Heusler main phase due to the small amount of Co-substitution for Ni. The achievement of the large exchange bias effect in the Ni38.8Co2.9Mn37.9Ti20.4 thin film is a significant addition to the existing multiple magneto-responsive effects in all-3d-metal Ni-Mn-based Heusler systems. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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20. Pressure effects on phase equilibria and solid solubility in MgO-Y2O3 nanocomposites.
- Author
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Akdoğan, E. K., Şavklιyιldιz, İ., Berke, B., Zhong, Z., Wang, L., Weidner, D., Croft, M. C., and Tsakalakos, T.
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DIAMOND anvil cell , *NANOCOMPOSITE materials , *X-ray diffraction , *HYDROSTATIC pressure , *CRYSTALLIZATION , *SOLID solutions - Abstract
We study the temperature and pressure dependence of phase evolution in the 0.5MgO-0.5Y2O3 nanocomposite system using a diamond anvil apparatus in conjunction with in situ synchrotron energy dispersive x-ray diffraction at 7 GPa hydrostatic pressure. At (298 K, 7.0 GPa), structural transformations in the Y2O3 phase are observed, giving rise to the co-existence of its cubic, hexagonal, and monoclinic polymorphs together with cubic MgO. An increase in temperature to 1273 K causes the crystallinity of the Y2O3 hexagonal and monoclinic phases to increase. Isothermal and isobaric hold at (1273 K, 7.0 GPa) for 60 min results in yttrium dissolution in cubic MgO, causing ∼1.0% expansive volumetric lattice strain despite the large differences in the ionic radii of the cations. Cooling the nanocomposite to (298 K, 0 GPa) after a 60 min soak yields four phase co-existence among cubic MgO and cubic, hexagonal, and monoclinic Y2O3. The residual MgO unit cell volume expansion is 0.69% at 298 K, indicating solid solution formation at room temperature despite large differences in the ionic radii of Mg2+ and Y3+. The macroscopic shrinkage due to densification is 3% by volume. Thermodynamic considerations suggest that the relative molar partial volume of Y3+ in MgO is a negative quantity, indicating that the partial molar volume of Y3+ in the solid solution is smaller than its molar volume in the pure state. Aging of the nanocomposites for 240 h does not change the observed 4 phase co-existence. We propose a crystallographic model in which the observed volumetric expansion of the MgO unit cell is primarily attributed to two hydrostatic expansive strain components accompanying solid solution formation: (i) Coulomb repulsion among O2- ions in the immediate vicinity of Mg2+ vacancies, and (ii) misfit strain due to differences in ionic radii upon Y3+ substitution on Mg2+ sites. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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21. In situ strain profiling of elastoplastic bending in Ti–6Al–4V alloy by synchrotron energy dispersive x-ray diffraction.
- Author
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Croft, M., Shukla, V., Akdoğan, E. K., Jisrawi, N., Zhong, Z., Sadangi, R., Ignatov, A., Balarinni, L., Horvath, K., and Tsakalakos, T.
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ELASTOPLASTICITY , *ALLOY fatigue , *BENDING moment , *SYNCHROTRON radiation , *X-ray diffraction , *VANADIUM alloys , *TITANIUM alloys , *ALUMINUM alloys - Abstract
Elastic and plastic strain evolution under four-point bending has been studied by synchrotron energy dispersive x-ray diffraction. Measured strain profiles across the specimen thickness showed an increasing linear elastic strain gradient under increasing four-point bending load up to ∼2 kN. The bulk elastic modulus of Ti–6Al–4V was determined as 118 GPa. The onset of plastic deformation was found to set in at a total in-plane strain of ∼0.008, both under tension and compression. Plastic deformation under bending is initiated in the vicinity of the surface and at a stress of 1100 MPa, and propagates inward, while a finite core region remains elastically deformed up to 3.67 kN loading. The onset of the plastic regime and the plastic regime itself has been verified by monitoring the line broadening of the (100) peak of α-Ti. The effective compression/tension stress-strain curve has been obtained from the scaling collapse of strain profile data taken at seven external load levels. A similar multiple load scaling collapse of the plastic strain variation has also been obtained. The level of precision in strain measurement reported herein was evaluated and found to be 1.5×10-5 or better. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
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22. Changing the exchange bias of spin valves by means of current pulses: Role of the Joule heating.
- Author
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Tang, X. L., Zhang, H. W., Su, H., Jing, Y. L., and Zhong, Z. Y.
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SPIN valves , *ALTERNATING currents , *ANTIFERROMAGNETISM , *ENERGY measurement ,HEATING effects of electric currents - Abstract
In-plane alternating pulses of current applied with an external magnetic field that changes the strength and direction of the exchange bias are observed in NiFe/Cu/NiFe/FeMn spin valves. To provide clear evidence of this spin-polarized current for antiferromagnets incorporated in spin valves, a series of measurements was carried out to rule out the influence of Joule heating caused by the pulse. The measurements revealed that Joule heating plays a minor role in the impact of exchange bias, thus providing more convincing evidence of the spin torque exerted on the interfacial antiferromagnetic moments. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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23. High-resolution diffuse x-ray scattering from threading dislocations in heteroepitaxial layers.
- Author
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Daniš, S., Holý, V., Zhong, Z., Bauer, G., and Ambacher, O.
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X-ray scattering , *EPITAXY , *OPTICAL diffraction , *GALLIUM nitride , *PHYSICS - Abstract
Diffuse x-ray scattering from epitaxial layers with screw dislocations perpendicular to the surface is calculated assuming correlated dislocation positions. The resulting intensity distribution was compared with a reciprocal-space map measured in a symmetric diffraction from a hexagonal GaN(0001) layer, and a good correspondence was achieved. From the fit, both the dislocation density and their correlation length were determined. [ABSTRACT FROM AUTHOR]
- Published
- 2004
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24. Application of absorption and refraction matching techniques for diffraction enhanced imaging.
- Author
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Hasnah, M., Oltulu, O., Zhong, Z., and Chapman, D.
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X-ray refraction , *ABSORPTION spectra - Abstract
Diffraction enhanced x-ray imaging (DEI) has simultaneous contrast sources from absorption, x-ray refraction gradients, and scatter-rejection (extinction). The combination of these contrast mechanisms generally allows many more features in objects to be observed compared to conventional radiography. In some instances or in specially prepared systems it is possible to eliminate one of the contrast mechanisms so as to create features that arise from a single contrast mechanism. With the DEI technique it is most interesting to either eliminate the absorption contrast of an object or conversely eliminate the refraction gradient contrast. We have explored both extremes of this contrast scale in order to better understand the DEI contrast mechanisms and to exploit the absence of a contrast mechanism for technical purposes. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2002
- Full Text
- View/download PDF
25. X-ray analysis of spontaneous lateral modulation in (InAs)[sub n]/(AlAs)[sub m] short-period superlattices.
- Author
-
Li, J. H., Holý, V., Zhong, Z., Kulik, J., Moss, S. C., Norman, A. G., Mascarenhas, A., Reno, J. L., and Follstaedt, D. M.
- Subjects
- *
SUPERLATTICES , *X-ray diffraction - Abstract
The lateral composition modulation in (InAs)[sub n]/(AlAs)[sub m] short-period superlattices was studied by means of synchrotron x-ray diffraction. By choosing specific diffraction vectors having a large component closely parallel to the modulation direction, we are able to observe a number of lateral satellite peaks around the zero-order short-period superlattice peak. A model, incorporating both composition and strain, is used to simulate the intensities of these satellites. Our results provide a quantitative fit and permit the evaluation of the composition amplitude. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
26. Stress dependence of magnetic domains in FeCoSiB amorphous films.
- Author
-
Peng, B., Xie, Q. Y., Zhang, W. L., and Zhong, Z. Y.
- Subjects
- *
STRAINS & stresses (Mechanics) , *FERROMAGNETIC materials , *MAGNETIC domain , *AMORPHOUS substances , *THIN films , *MAGNETIC force microscopy , *MATERIALS science - Abstract
The work reports the effect of a tensile stress on the magnetic domain of FeCoSiB amorphous films. The domain structures of the unstressed and stressed FeCoSiB amorphous films with different tensile strains have been studied by magnetic force microscopy (MFM). With the increase of the tensile stress in the samples, it has been observed that the domain structures transform from irregular domains into parallel strip domains, and magnetic contrasts decrease. The MFM image disappears when the tensile stress is strong enough. A model has been presented to explain the evolution of the domain structures under the tensile stress. The effects of the stress on the domain of the films have been discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
27. Microstructure, magnetic and magnetocaloric properties in Ni42.9Co6.9Mn38.3Sn11.9 alloy ribbons.
- Author
-
Ma, S. C., Ge, Q., Yang, S., Liu, K., Han, X. Q., Yu, K., Song, Y., Zhang, Z. S., Jiang, Q. Z., Chen, C. C., Liu, R. H., and Zhong, Z. C.
- Subjects
- *
NICKEL alloys , *MAGNETOCALORIC effects , *METAL microstructure - Abstract
The microstructure, magnetic and magnetocaloric properties are investigated in the melt-spun and annealed Ni42.9Co6.9Mn38.3Sn11.9 ribbons. The columnar grains grow perpendicular to ribbon surfaces. After annealing, the grain size increases greatly. Meanwhile, the parent phase is suppressed and therefore
L 10 martensite predominates, indicating obvious shift of martensitic transformation to high temperature. More interestingly, the martensite variants are distinctly observed on the fractured cross-section of annealed ribbons, not just on the free surface in general. The significant enhancement of magnetic entropy change and effective refrigerant capacities with relatively smaller thermal hysteresis make annealed ribbons potential candidate in magnetic refrigeration around room temperature. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
28. Effects of intergranular phase on the coercivity for MnBi magnets prepared by spark plasma sintering.
- Author
-
Cao, J., Huang, Y. L., Hou, Y. H., Zhang, G. Q., Shi, Z. Q., Zhong, Z. C., and Liu, Z. W.
- Subjects
- *
MANGANESE compounds , *SINTERING , *COERCIVE fields (Electronics) - Abstract
MnBi magnets with a high content of low temperature phase (LTP) and excellent magnetic properties were prepared by spark plasma sintering (SPS) using ball milling powders as precursors without magnetic purification. A complicated intergranular phase, which contains Mn phase, Bi phase, MnO phase, and even amorphous phase in MnBi magnets, was characterized and reported systematically. It was found that the formation of intergranular phase which was contributed by ball milling precursors and sintering mechanism, jointly, had important influence on the magnetic properties. The appropriate content of intergranular phase was beneficial in improving the coercivity due to the strong magnetic isolation effects. The optimum magnetic properties with
M r=26.0 emu/g,H ci= 7.11 kOe and (BH )max=1.53 MGOe at room temperature, and a maximum valueH ci= 25.37 kOe at 550 K can be obtained. Strongly favorable magnetic properties make SPSed MnBi magnets an attractive candidate material for small permanent magnets used in high-temperature applications. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
29. Tuning the metamagnetism in a metallic helical antiferromagnet.
- Author
-
Ma, S. C., Liu, K., Ma, C. C., Ge, Q., Zhang, J. T., Hu, Y. F., Liu, E. K., and Zhong, Z. C.
- Subjects
- *
METAMAGNETISM , *ANTIFERROMAGNETISM , *MARTENSITE , *INDIUM , *MAGNETIC entropy , *MAGNETOCALORIC effects - Abstract
The antiferromagnetic (AFM)-ferromagnetic (FM) conversion in martensite was observed in Mn/Ni-substitution upon FM elements, such as Fe or Co, in MnNiGe helical antiferromagnets. Here, we report an AFM-FM conversion and consequently a sharp magnetic-field-driven metamagnetic martensitic transformation from paramagnetic (PM) austenite to FM martensite in the Ni- and Mnsubstituted MnNiGe alloys with indium, a non-magnetic and large-sized main group element. Accordingly, a giant magnetocaloric effect such that a twofold increase of the magnetic entropy change in MnNi0.92GeIn0.08 and even a nearly threefold increase in the Mn0.92NiGeIn0.08 alloy is obtained with respect to the MnNiGe0.95In0.05 alloy. The origin of AFM-FM conversion and resultantly sharp magnetic-field-induced PM-FM metamagnetic transformation is discussed based on the first-principles calculations and X-ray absorption spectroscopic results. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
30. Driving higher magnetic field sensitivity of the martensitic transformation in MnCoGe ferromagnet.
- Author
-
Ma, S. C., Ge, Q., Hu, Y. F., Wang, L., Liu, K., Jiang, Q. Z., Wang, D. H., Hu, C. C., Huang, H. B., Cao, G. P., Zhong, Z. C., and Du, Y. W.
- Subjects
- *
MARTENSITIC transformations , *DISPLACIVE transformations , *FERROMAGNETIC materials , *FERROMAGNETISM , *MAGNETOCALORIC effects - Abstract
The sharp metamagnetic martensitic transformation (MMT) triggered by a low critical field plays a pivotal role in magnetoresponsive effects for ferromagnetic shape memory alloys (FSMAs). Here, a sharper magnetic-field-induced metamagnetic martensitic transformation (MFIMMT) is realized in Mn1-xCo1+xGe systems with a giant magnetocaloric effect around room temperature, which represents the lowest magnetic driving and completion fields as well as the largest magnetization difference around MFIMMT reported heretofore in MnCoGe-based FSMAs. More interestingly, a reversible MFIMMT with field cycling is observed in the Mn0.965Co0.035Ge compound. These results indicate that the consensus would be broken that the magnetic field is difficult to trigger the MMT for MnCoGe-based systems. The origin of a higher degree of sensitivity of martensitic transformation to the magnetic field is discussed based on the X-ray absorption spectroscopic results. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
31. Effects of rapid recurrent annealing on structure and magneto-optical properties of garnet films.
- Author
-
Zhang, S. J., Guo, X. Y., Zhang, F. P., Xu, C. L., Shi, F. L., Zhang, H. W., Zhong, Z. Y., and Guo, B. J.
- Subjects
- *
BISMUTH , *OPTICAL disk drives , *MORPHOLOGY - Abstract
Presents information on a study which discussed a method to improve the morphology and microstructure of sputtered bismuth-substituted garnet films for optical storage. Examination of the composition and surface morphology of films by scanning electron microscopy and electron probe microanalysis; Crystallization process of as-deposited amorphous films; Measurement of the magneto-optical Kerr hysteresis.
- Published
- 1993
- Full Text
- View/download PDF
32. Ordered domain lateral location, symmetry, and thermal stability in Ge:Si islands.
- Author
-
Richard, M.-I., Malachias, A., Schülli, T. U., Favre-Nicolin, V., Zhong, Z., Metzger, T. H., and Renaud, G.
- Subjects
- *
NANOPARTICLE synthesis , *THIN films , *ANNEALING of semiconductors , *GERMANIUM silicide , *EPITAXY , *BAND gaps , *THERMAL stability - Abstract
Compositional atomic ordering is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report on a method based on x-ray diffuse scattering close to basis forbidden Bragg reflections to infer the lateral location, the symmetry, and the thermal stability of ordered domains in GeSi dome-shaped islands on Si(001) after growth and during annealing. We observe that atomic ordering does not disappear after annealing, demonstrating that it is a resilient metastable phenomenon. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
33. Ordered domain lateral location, symmetry, and thermal stability in Ge: Si islands.
- Author
-
Richard, M.-I., Malachias, A., Schülli, T. U., Favre-Nicolin, V., Zhong, Z., Metzger, T. H., and Renaud, G.
- Subjects
- *
GERMANIUM , *THERMAL stability , *ATOMIC layer epitaxial growth , *THERMAL properties of nanoparticles , *THIN films , *THERMAL properties - Abstract
Compositional atomic ordering is a crucial issue in the epitaxial growth of nanoparticles and thin films. Here, we report on a method based on x-ray diffuse scattering close to basis forbidden Bragg reflections to infer the lateral location, the symmetry, and the thermal stability of ordered domains in GeSi dome-shaped islands on Si(001) after growth and during annealing. We observe that atomic ordering does not disappear after annealing, demonstrating that it is a resilient metastable phenomenon. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
34. Effect of graphene on photoluminescence properties of graphene/GeSi quantum dot hybrid structures.
- Author
-
Chen, Y. L., Ma, Y. J., Chen, D. D., Wang, W. Q., Ding, K., Wu, Q., Fan, Y. L., Yang, X. J., Zhong, Z. Y., Xu, F., and Jiang, Z. M. `
- Subjects
- *
OPTICAL properties of graphene , *PHOTOLUMINESCENCE , *QUANTUM dots , *GERMANIUM silicide , *CHARGE exchange - Abstract
Graphene has been discovered to have two effects on the photoluminescence (PL) properties of graphene/GeSi quantum dot (QD) hybrid structures, which were formed by covering monolayer graphene sheet on the multilayer ordered GeSi QDs sample surfaces. At the excitation of 488 nm laser line, the hybrid structure had a reduced PL intensity, while at the excitation of 325 nm, it had an enhanced PL intensity. The attenuation in PL intensity can be attributed to the transferring of electrons from the conducting band of GeSi QDs to the graphene sheet. The electron transfer mechanism was confirmed by the time resolved PL measurements. For the PL enhancement, a mechanism called surface-plasmon-polariton (SPP) enhanced absorption mechanism is proposed, in which the excitation of SPP in the graphene is suggested. Due to the resonant excitation of SPP by incident light, the absorption of incident light is much enhanced at the surface region, thus leading to more exciton generation and a PL enhancement in the region. The results may be helpful to provide us a way to improve optical properties of low dimensional surface structures. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
35. The antiferromagnetic-ferromagnetic conversion and magnetostructural transformation in Mn-Ni-Fe-Ge ribbons.
- Author
-
Ma, S. C., Hou, D., Yang, F., Huang, Y. L., Song, G., Zhong, Z. C., Wang, D. H., and Du, Y. W.
- Subjects
- *
FERROMAGNETIC-antiferromagnetic transitions , *RIBBONS , *MAGNETIZATION , *PARAMAGNETIC materials , *FERROMAGNETISM - Abstract
Two Mn-Ni-Fe-Ge ribbon samples are prepared. The ribbons reveal the complicated magnetization process with the variation of temperature and magnetic field. Strikingly, the antiferromagneticferromagnetic conversion and competition are observed in the TiNiSi-type phase in these ribbons. The required field to complete the conversion decreases with increasing temperature. When completing conversion, the coupled magnetostructural transformation from the ferromagnetic TiNiSi-type to paramagnetic Ni2In-type state with large magnetic entropy changes near room temperature is achieved for these ribbons. However, it is found that the magnetic field would be difficult to drive ferromagnetic-paramagnetic magnetostructural transformation for these ribbons unlike temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
36. Giant magnetocaloric and magnetoresistance effects in ferrimagnetic Mn1.9Co0.1Sb alloy.
- Author
-
Ma, S. C., Hou, D., Gong, Y. Y., Wang, L. Y., Huang, Y. L., Zhong, Z. C., Wang, D. H., and Du, Y. W.
- Subjects
- *
MAGNETIC fields , *ELECTRIC resistance , *MAGNETOCALORIC effects , *ANTIFERROMAGNETIC resonance , *FERRIMAGNETIC resonance - Abstract
Magnetic and transitional behaviors are investigated in Mn1.9Co0.1Sb intermetallic compound. Mn2Sb is a simple ferrimagnet with Neel temperature around 550 K. The Co-introduction results in the appearance of antiferromagnetic state, and therefore, the first-order magnetic transition occurs between antiferromagnetic and ferrimagnetic state, which can be induced by temperature/magnetic field, in Mn1.9Co0.1Sb alloy. Accordingly, a magnetic entropy change as high as 5 J kg-1K-1 and a large magnetoresistance of 46% under the field change of 10 and 50 kOe are achieved, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
37. Peculiarity of magnetoresistance in high pressure annealed Ni43Mn41Co5Sn11 alloy.
- Author
-
Ma, S. C., Wang, D. H., Zhong, Z. C., Luo, J. M., Xu, J. L., and Du, Y. W.
- Subjects
- *
MAGNETIC properties of shape memory alloys , *MAGNETORESISTANCE , *MARTENSITIC transformations , *PHASE transitions , *X-ray diffractometers - Abstract
Magnetic and resistance measurements have been carried out on a Ni43Mn41Co5Sn11 alloy annealed under high-pressure. Due to the existence of the intermediate phase, a change of slope in the temperature dependence of resistivity curves has been observed prior to the martensitic transformation for the high-pressure annealed alloy. As a consequence, two successive magnetoresistance peaks with the same sign are achieved around room-temperature, corresponding to the martensitic transformation and intermediate phase transition, respectively. The origin of the peculiarity of magnetoresistance properties in high-pressure annealed Ni43Mn41Co5Sn11 alloy is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
38. Linewidth of the infrared absorption spectra due to bound-to-continuum transition in GaAs/Al[sub x]Ga[sub 1-x]As multiple quantum well structures.
- Author
-
He, Yunpeng, Zhu, Q. S., Zhong, Z. T., Zhang, G. Z., Xiao, J., Cao, Z. P., Sun, X. H., and Yang, H. Z.
- Subjects
- *
ABSORPTION spectra , *QUANTUM wells - Abstract
We have observed an extremely narrow absorption spectrum due to bound-to-continuum transition in GaAs/Al[sub x]Ga[sub 1-x]As multiple quantum wells (MQWs). Its linewidth is only about one tenth of the values reported previously. Our calculation indicates that the broadening of the excited state in the continuum has little contribution to the absorption linewidth. We have grown a sample whose MQW region contains two kinds of wells with a minor thickness inhomogeneity. Its resultant absorption linewidth is six times as large as that of homogeneous well sample, which is in good agreement with our theoretical analysis. Thus we can suggest that the wider absorption spectra reported by many authors may be due to the well width inhomogeneity. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 1998
- Full Text
- View/download PDF
39. High-pressure phase transformations in MgO-Y2O3 nanocomposites.
- Author
-
Akdoğan, E. K., Şavklıyıldız, İ., Berke, B., Zhong, Z., Wang, L., Vaughan, M., and Tsakalakos, T.
- Subjects
- *
NANOCOMPOSITE materials , *PHASE transitions , *POLYCRYSTALLINE semiconductors , *OPTICAL properties , *THERMODYNAMICS - Abstract
Temperature and pressure dependence of phase evolution in 0.5 MgO-0.5 Y2O3 is studied using the diamond anvil method. At 300 K and 5.5 GPa, transformations in Y2O3 are observed, resulting in co-existence of cubic, hexagonal, and monoclinic phases. Heating to 1293 K results in increased crystallinity and increase in hexagonal and monoclinic phase content. Isothermal and isobaric hold at 1273 K and 5.5 GPa for 120 min results in yttrium dissolution in cubic MgO, causing 0.83% volumetric strain. Cooling to 300 K and 0 GPa yields a four phase co-existence among cubic MgO and cubic, hexagonal, and monoclinic Y2O3. The residual MgO unit cell volume expansion is 0.67% at 300 K, indicating solid solution formation. Aging of the nanocomposites for 240 h does not change the observed 4 phase co-existence. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
40. Multiple scattering effects in strain and composition analysis of nanoislands by grazing incidence x rays.
- Author
-
Richard, M.-I., Favre-Nicolin, V., Renaud, G., Schülli, T. U., Priester, C., Zhong, Z., and Metzger, T.-H.
- Subjects
- *
SCREEN-film radiography , *X-rays , *GRAZING , *GERMANIUM , *SILICON , *NANOSTRUCTURED materials , *SCATTERING (Physics) , *COMPUTER simulation - Abstract
Experiments and numerical simulations based on finite element modeling show that the x-ray intensity scattered by comparatively large nanostructures on a substrate is not simply related to their strain in experiments using either grazing incidence or exit because of multiple scattering effects. However, whatever the nanostructure size, the composition profiles are correctly extracted from grazing incidence multiwavelength anomalous scattering. These effects are illustrated for the structural analysis of Ge dome-shaped islands grown on Si(001). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
41. Effect of overgrowth temperature on shape, strain, and composition of buried Ge islands deduced from x-ray diffraction.
- Author
-
Stangl, J., Hesse, A., Holý, V., Zhong, Z., Bauer, G., Denker, U., and Schmidt, O. G.
- Subjects
- *
TEMPERATURE , *OPTICAL diffraction - Abstract
We have investigated a series of samples containing SiGe islands capped at different growth temperatures. A layer of islands formed by deposition of 5 ML of pure Ge was capped with Si, deposited at temperatures of 460, 540, and 630 °C, respectively. The Ge composition profile and the shape of the buried islands are deduced from x-ray diffraction data. While for capping at high substrate temperatures a significant dilution of the Ge content and a flattening of the islands occur, capping at low temperatures maintains a high aspect ratio and a high Ge content of the islands. The maximum in-plane strain in the island remains as high as 0.005 for capping at low temperatures. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
42. Time-dependence of luminescence of nanoparticles of Eu[sub 2]O[sub 3] and Tb[sub 2]O[sub 3] deposited on and doped in alumina.
- Author
-
Gedanken, A., Reisfeld, R., Sominski, L., Zhong, Z., Koltypin, Yu., Panczer, G., Gaft, M., and Minti, H.
- Subjects
- *
NANOPARTICLES , *LUMINESCENCE , *DOPED semiconductors - Abstract
Nanoparticles of Eu[sub 2]O[sub 3] and Tb[sub 2]O[sub 3] have been prepared using ultrasound radiation and were deposited sonochemically on microspherical alumina particles. In a different sonochemical reaction Eu[sub 2]O[sub 3] and Tb[sub 2]O[sub 3] were doped into nanophased alumina particles. For both systems the decay times of the fluorescence was measured. The luminescence of the alumina substrate was found to be much shorter than that of the rare-earth oxides. Differences between the decay times of the deposited and doped materials are accounted for by the stronger guest-host interaction and absence of concentration quenching in the doped material. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2000
- Full Text
- View/download PDF
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