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G.F. Zhou

Other affiliations: Academia Sinica
Bio: G.F. Zhou is an academic researcher from University of Amsterdam. The author has contributed to research in topics: Magnetization & Intermetallic. The author has an hindex of 9, co-authored 26 publications receiving 325 citations. Previous affiliations of G.F. Zhou include Academia Sinica.

Papers
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Journal ArticleDOI
TL;DR: In this article, the temperature and field dependence at 4.2 K of the magnetization of Y2Fe17−xAlx and Ho2Fe 17−xalx (x ≤ 10) compounds has been studied.

125 citations

Journal ArticleDOI
TL;DR: In this article, the magnetic properties of Gd 2 Fe 17− x M x compounds with M=Al or Mn were investigated, and it was shown that substitution of Al or Mn, although it reduces the Fe magnetization in different ways, has only little influence on the intersublattice coupling strength.

39 citations

Journal ArticleDOI
TL;DR: In this article, the magnetisation measurements for the Curie temperatures and Co moments were estimated, and values for the J RT coupling constants were derived for the compounds with a magnetic R component, with the determined J RT values decrease with increasing atomic number of the rare earth component.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the field dependence of the magnetization at 4.2 K was studied in fields up to 35 T for the pseudobinary compounds R2Fe17−xAlx (R = Tb, Dy, Er and Tm).
Abstract: The field dependence of the magnetization at 4.2 K was studied in fields up to 35 T for the pseudobinary compounds R2Fe17−xAlx (R = Tb, Dy, Er and Tm). Values for the intersublattice-coupling strength were derived from a mean-field analysis of the magnetic isotherms. For the series Dy2Fe17−xAlx we determined the concentration dependence of the Curie temperature and the compensation temperature. A magnetic phase diagram for this series has been constructed.

25 citations

Journal ArticleDOI
TL;DR: In this article, the magnetic isotherms were analyzed with a mean-field model and the magnetic coupling constant between the moments of rare earth and Co in the Hamiltonian H = ΣRCo2JRCoSRSCo was determined and compared with those obtained for RCo4B and R2Co14B compounds.

18 citations


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Book
28 Sep 2004
TL;DR: Mechanical Alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill as mentioned in this paper.
Abstract: Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or prealloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and mechanochemical synthesis of materials have been critically reviewed after discussing the process and process variables involved in MA. The often vexing problem of powder contamination has been analyzed and methods have been suggested to avoid/minimize it. The present understanding of the modeling of the MA process has also been discussed. The present and potential applications of MA are described. Wherever possible, comparisons have been made on the product phases obtained by MA with those of rapid solidification processing, another non-equilibrium processing technique.

3,773 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the experimental values of the magnetic intersublattice-coupling constants in rare-earth (R) transition-metal (T) intermetallics, derived from high-field magnetization measurements on single-crystalline powder particles that are free to be oriented by the applied magnetic field.

158 citations

Journal ArticleDOI
TL;DR: In this article, the temperature and field dependence at 4.2 K of the magnetization of Y2Fe17−xAlx and Ho2Fe 17−xalx (x ≤ 10) compounds has been studied.

125 citations

Journal ArticleDOI
TL;DR: A review of the literature on substitutions and their effect on the properties of the 90 K superconductor YBa 2 Cu 3 O δ (YBCO) can be found in this paper.
Abstract: The 90 K superconductor, YBa 2 Cu 3 O δ (YBCO), has proved to be highly adaptable chemically as it can accommodate a wide variety of cationic and anionic substitutions. Indeed, the majority of the chemical elements, excluding noble gases and actinides, have been reported to substitute to some extent into the YBCO structure. This review covers the literature on such substitutions and their effect on the properties of YBCO. Reported solubility limits are given, together with crystal symmetry and trends in unit cell parameters with dopant concentration. The dopant site is considered; this is additionally complex in the case of copper substitution because of the two distinct copper sites in the crystal structure. The effect of the dopant on the critical temperature, T c , is reviewed; the literature is often contradictory due to the dual effects of variable oxygen content and the nature of the dopant. Preparation methods appear to have an effect on solubility limits, crystal symmetry and T c , Also, the methods used to determine solubility limits are often imprecise which can lead to contradictions. The magnetic properties of doped materials are reviewed; for some dopants, particularly the magnetic lanthanides, antiferromagnetism and superconductivity co-exist. The related RBa 2 Cu 3 O δ phases (R = lanthanide), their structure, properties and behaviour on doping are reviewed in a similar way. For the larger rare earths, the related systems R 1+ x Ba 2- x CU 3 O δ , are reviewed; as x increases, the transition temperature decreases and compositions R 1.5 Ba 1.5 Cu 3 O δ are semiconducting. The upper and lower solubility limit changes with R, and for R = Dy, the upper limit is x = 0 composition, LaBa 2 Cu 3 O δ , cannot be prepared in air since substitution of La onto the Ba site occurs, forming the Ba-deficient solid solutions. The discovery of superconductivity above liquid nitrogen temperatures in YBa 2 Cu 3 O 7 , has generated a vast quantity of research; to date, > 20 000 papers have appeared on the 123 materials (source: BIDS). This review, therefore, cannot be comprehensive, but attempts to highlight important substitutions, their effect on the properties of YBCO and any contradictions in the literature.

100 citations

Journal ArticleDOI
TL;DR: The magnetic properties of a series of Nd2Fe17−xAlx solid solutions, with x equal to 2.04, 4.01, 5.97, 7.94, and 9.06, have been studied by magnetic measurements, neutron diffraction, and Mossbauer spectroscopy as mentioned in this paper.
Abstract: The magnetic properties of a series of Nd2Fe17−xAlx solid solutions, with x equal to 2.04, 4.01, 5.97, 7.94, and 9.06, have been studied by magnetic measurements, neutron diffraction, and Mossbauer spectroscopy. Magnetization studies indicate that the Curie temperature increases from 330 K in Nd2Fe17 to a maximum of ∼470 K at an x of 3.5. The compounds crystallize in the Th2Zn17 structure with lattice parameters and unit cell volumes which increase linearly with increasing aluminum content. The neutron diffraction results indicate that aluminum atoms are excluded from the 9d site, prefer the 18h site at low aluminum content, and prefer the 6c and 18f sites at high aluminum content. At 10 K the magnetic moments of the iron and neodymium atoms are collinear and take up a basal orientation at all aluminum contents. The moments decrease with increasing aluminum content and the magnetic moments per unit cell at 10 K are in excellent agreement with the 4.2 K saturation magnetization values. At 295 K the Nd2Fe17...

91 citations