X.Y.Le
,
S.Yan
,
W.J.Zhao
金属学报(英文版)
The surface defect distribution in stainless steel irradiated with intense pulsed ion beam(IPIB) of current density above 60A/cm2 and acceleration voltage 300-500keV wasdiscussed and analyzed. The defects near the surface of stainless steel were generatedin two ways: (1) generated by the bombardment of energetic ions and (2) induced bythe high level stress near the surface. Thus the temperature and stress distributionsnear the steel surface were calculated by means of our STEIPIB code, which treatedwith the thermal-dynamical process in the target irradiated by the IPIB. Based onthese distributions, the generations and movements of these defects were discussedand compared with the experiment results.
关键词:
IPIB
,
null
,
null
Hakan Colak
材料科学技术（英文）
This paper reported the synthesis, crystal structure and electrical conductivity properties of Ni-doped ZnO powders (i.e. Zn1-XNiXObinary system, X=0, 0.0025, 0.005, 0.0075 and in the range 0.01≤X≤0.15). I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Zn1-XNiXObinary system, were determined by X-ray diffraction (XRD). The widest range of the I-phase was determined as 0≤X≤0.03 at 1200°C; above this range the mixed phase was observed. The impurity phase was determined as NiO when compared with standard XRD data, using the PDF program. We focused on single I-phase ZnO samples which were synthesized at 1200°C because of the widest range of solubility limit at this temperature. It was observed that the lattice parameters a and c of the I-phase decreased with Ni doping concentration. The morphology of the I-phase samples was analyzed with a scanning electron microscope. The electrical conductivity of the pure ZnO and single I-phase samples were studied by using the four-probe dc method at temperatures between 100 and 950°C in air atmosphere. The electrical conductivity values of pure ZnO and 3 mol% Ni-doped ZnO samples at 100°C were 2×10-6 and 4.8×10-6Ω-1?cm-1, and at 950°C they were 1.8 and 3.6Ω-1?cm-1, respectively. In other words, electrical conductivity increased with Ni doping concentration.
关键词:
II-VI semiconductors
Applied Physics Letters
The effect of nonmagnetic Y partial substitution at the Dy site in Dy(1-x)Y(x)MnO(3) up to x=0.2 on magnetism, specific heat, and ferroelectricity is investigated, which resulted in a preliminary multiferroic phase diagram. It is revealed that the Y partial substitution suppresses the Dy-spin ordering point (T(Dy)) and ferroelectric ordering point (T(FE)) but enhances the Mn-spin ordering point (T(N)). The interaction between the spins of Dy and Mn is remarkably affected by Y substitution. The measured electrical polarization depends on the Y substitution in a complex way because the ferroelectricity is sensitive to the interaction between the spins of Dy and Mn. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3536506]
关键词:
ferroelectricity;polarization
沈世妃马伟民闻雷郭易芬王华栋尹凯
金属学报
用柠檬酸螯合法制备Y2-x-yGdxEuyO3纳米粉体(x+y≤ 2), 通过FTIR, XRD和SEM分析了制备过程中的物相变化以及pH值对粉体 形貌的影响. 测试了Y2-x-yGdxEuyO3 晶格常数和晶胞体积, 分析了Gd与Eu在Y2O3中的固溶行为及其发光性能. 结果表明: 在pH<3的体系中制备Y2-x-yGdxEuyO3粉体较为适合, 经900 ℃煅烧2 h可完全合成出立方相的Y2-x-yGdxEuyO3; 在pH=1时, 加入少量乙二醇 (5%, 体积分数) 时得到粉体形貌最佳, 粒径约90 nm, 近球形. 样品的发光性能和Y, Gd的配比以及Eu的含量有关, 当化学配比为Y0.2Gd1.65Eu0.15O3时样品发光强度最高,y值超过0.15会发生浓度猝灭, 导致发光强度降低.
关键词:
柠檬酸
,
Y2−x−yGdxEuyO3 nanopowder
,
solid solution
,
luminescence performance
材料科学技术（英文）
The glass-forming ability (GFA) of Nd(70-x)Fe(20)Al(10)Y(x) and Nd(60-x)Fe30Al(10)Y(x) (0 less than or equal to x less than or equal to15) alloys produced by Cu mold casting was investigated. Except Y = 5 at. pct, bulk amorphous Nd(70-x)Fe(20)Al(10)Y(x) alloys up to 2 mm in diameter were obtained. The GFA for Nd(60-x)Fe(30)Al(10)Y(x) alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd(60)Fe(30)Al(10) alloy. The Nd(60)Fe(20)Al(10)Y(10) and Nd(60)Fe(30)Al(10) alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd(55)Fe(20)Al(10)Y(15) alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, T(g), and the supercooled liquid region, DeltaT(x), are 776 K and 58 K, respectively, The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.
关键词:
Nd-based alloys;glass forming ability;liquidus temperature;thermal;stability;supercooled liquid region;bulk amorphous-alloys;metallic glasses;transition temperature;thermal-stability;atomic size;ni alloys;cu;alloys;diameter;tm
Physica B-Condensed Matter
The magnetic properties and magnetocaloric effect of Tb(1-x)Y(x)CoC(2) (x = 0, 0.1, 0.2, 0.3, 0.4) compounds have been investigated systematically. All the compounds undergo second-order transitions from paramagnetic to ferromagnetic states without thermal and magnetic hysteresis. With increasing Y content from 0 to 0.4, the Curie temperatures decrease nearly linearly from 28 to 18 K. The nature of the second-order phase transitions can be confirmed by Arrott plots. For Tb(0.6)Y(0.4)CoC(2) compound, the maximum value of the magnetic entropy change -Delta S(M) at 20 K is 9.35 J kg(-1) K(-1) for an external field change of 5T (5.14 J kg(-1) K(-1) for 2T). The large reversible magnetic entropy change makes Tb(0.6)Y(04)CoC(2) compound an attractive candidate for the application at hydrogen liquefaction temperature. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
Curie temperature;Magnetocaloric effect;Magnetic properties;ac susceptibility
Materials Letters
The dynamic hysteresis in a planar X-Y model as a function of frequency and amplitude of external field, at a temperature far below its Curie point, is studied by means of Monte Carlo (MC) method. The evolution of hysteresis dispersion is simulated in details and the earlier proposed scaling on the hysteresis dispersion is confirmed in the present system. It is predicted that the unique characteristic time for domain reversal is inversely proportional to the field amplitude once the amplitude is not very small. (C) 2002 Elsevier Science B.V. All rights reserved.
关键词:
dynamic hysteresis;scaling;planar X-Y model;kinetic ising-model;magnetic hysteresis;phase-transition;films
Journal of Physical Chemistry C
We report the electrical, thermal, magnetic, and thermoelectric properties of Y-doped Ca(3)Co(4)O(9) from 300 down to 5 K. The results indicate that with Y doping, the increase of resistivity originates from the decreases of carrier concentration and mobility, while the increase of Seebeck coefficient is caused by the reduction of carrier concentration together with the enhanced electronic correlation. Point-defect scattering, is the dominant thermal transport mechanism in this system. Due to the considerable difference in mass between Y(3+) and Ca(2+), thermal conductivity is observably suppressed by doping. The substitution of Y also disturbs the interlayer ferrimagnetic coupling. The ground state of this System converts front ferrimagnetism to paramagnetism gradually. The alteration of transport properties of Ca(3-x)Y(x)Co(4)O(9) reveals two Crossovers: the transition from Fermi-liquid-like metal to thermally activated semiconductor occuring at x approximate to 0.25, and the transition from thermally activated semiconductor to two-dimensional variable range hopping semiconductor occurring at x approximate to 0.5. The optimal thermoelectric response In Ca(3-x)Y(x)Co(4)O(9) is found to exist only at the critical state after which the doping-induced metal-insulator transition takes place. Oil the basis of these experimental results, a possible phase diagram for Ca(3-x)Y(x)Co(4)O(9) is proposed.
关键词:
temperature thermoelectric properties;giant magnetoresistance;solid-solutions;conductivity;electron;system;ca3co4o9+delta;thermopower;crystals;behavior
