Fu LIU
,
Fuping WANG
,
Tadao Shimizu
,
Kaoru Igarashi
,
Liancheng ZHAO
材料科学技术（英文）
The ceramic coating was formed by using microarc oxidation (MAO) in the electrolytic solution of β-Glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The microstructure, phase structure and phase composition were investigated with scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), X-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). Investigation of the chemical composition of the coating with EDX revealed that Ca and P of high concentration existed in oxide films. XRD patterns indicated that the oxide film was composed of only anatase at low voltage discharge, and that rutile peaks appear in addition to anatase peak with increasing MAO voltage. Despite the existence of Ca and P, compounds concerning Ca and P were not detected in the oxide film.
关键词:
Microarc oxidation
,
null
,
null
Physica B-Condensed Matter
Magnetization and AC susceptibility measurements have been carried out to investigate the magnetic phase transition of Gd1-xDYxCo2 compounds. It is revealed that the type of the magnetic phase transition changes from second order to first order around x(c) = 0.8 with the increase of Dy concentration. A satisfactory explanation is offered in terms of the Inoue-Shimizu model. The exchange-enhanced susceptibility of the compounds within the exchange-enhanced paramagnetism model is in good agreement with the 3d-electrons susceptibility deduced by Inoue-Shimizu model. (C) 2003 Elsevier Science B.V. All rights reserved.
关键词:
Laves phase RCo2;magnetic phase transition;susceptibility;intermetallic compounds;order
Physica B-Condensed Matter
X-ray powder diffraction and magnetization measurements reveal that light rare earth and heavy rare earth have different effects on the structure, Curie temperature and magnetic phase transition of the compounds R(Co1-xGax)(2) (R = Nd, Gd, Tb, Dy) (x = 0.0-0.3). The lattice constant exhibits a giant increase with increasing Ga concentration in all compounds. The Curie temperature shows no variation for R = Nd, a monotonic decrease for R = Gd and a maximum for R=Tb and Dy, respectively. The Curie temperature is strongly related with volume expansion, in which a critical value of a(c) approximate to 7.26 Angstrom is reached. The observed magnetic transition in all compounds is well explained within the framework of the Inoue-Shimizu model. It is revealed that both the lattice constant and the Curie temperature have a strong relationship with the order of the magnetic phase transition. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
structure;Curie temperature;magnetic phase transition;itinerant-electron metamagnetism;intermetallic compounds;ac;susceptibility;order;temperature;behavior;r(co;yco2
