ngtao Jia

Nanophased CoFe2O4 prepared by combustion method

The combustion method has been utilized to prepare nanophased powders of cobalt spinel ferrite using glycine as fuel. Structural and magnetic properties of the products were investigated with an X-ray diffractometer, a surface analyzer, and an alternating gradient magnetometer, respectively. Cobalt spinel ferrite prepared by the present method can easily form the well-crystallized nanoscale particles with a large specific surface area. The magnetization and coercivity show a strong dependence on the G/N (glycine to nitrates) ratio in the range from 0.2 to 1.0.

MICROSTRUCTURE, MAGNETIC, AND MAGNETO-OPTICAL PROPERTIES OF CHEMICAL SYNTHESIZED CO-RE (RE=HO, ER, TM, YB, LU) FERRITE NANOCRYSTALLINE FILMS

The sol-gel synthesis of Co–RE (RE=Ho, Er, Tm, Yb, Lu) ferrite nanocrystalline films was accomplished on monocrystalline silicon substrates, and the influence of RE ions on structure, magnetic, and magneto-optical (MO) properties of the resultant ferrites was examined. The results obtained reveal that, when x⩽0.2, the CoFe2−xRExO4 ferrite films have pure spinel phase with slightly enlarged cell constants and lattice distortion due to the large radii of RE ions. The RE ions tend to decrease the room-temperature magnetization as well as the Curie point of products, and may have a certain contribution to coercive force except for a nonmagnetic Lu3+ ion. For the present optical structure in which MO layers are substrated on silica, Co–RE ferrite films show the peak Kerr rotation at a shorter wavelength than the CoFe2O4 film, and Er or Tm doped samples exhibit an interesting enhancement of the MO effect.

Extraction of scandium from ion-adsorptive rare earth deposit by naphthenic acid

Abstract An extraction method for producing high purity Sc(III) from ion-adsorptive rare earth deposit (IARED) is presented. Naphthenic acid diluted with iso -octanol and sulfated kerosene is selected as the extractant, chloride acid as the scrubbing and stripping solution. By two extraction processes in naphthenic acid system, scandium is concentrated from 0.02–0.04% to 15–20% (wt.), and further purified to 99.99–99.999% grade. The stoichiometry of the extraction of Sc(III) with naphthenic acid was also determined.

Microstructure and magneto-optical properties of CoFe1.9RE0.1O4 nanocrystalline films on quartz substrates

A novel family of composited oxides, Co–RE ferrites (RE=rare earth), has been fabricated on quartz substrates by a sol-gel method. The studies on the microstructure and magneto-optical effects of the Co–RE ferrite films were carried out. It has been found that the doping of Co ferrite with Yb or Lu ion notably enhance the magneto-optical rotations in the spectral range of 350–420 nm, which made them very promising to be used for magneto-optical recording at short wavelengths in the future.

Preparation of ceria with large particle size and high appearance density

Abstract Cerium is one of the most abundant rare earth elements in both bastnasite and monazite. Ceria has been widely used in optical, catalytic, electrolyte, and sensor materials, with unique performances. With the development of functional materials, great interest has been focused on the synthesis and characterization of specific fine/mesoporous ceria powder. In this study, the modified precipitation and recrys-tallization processes combined with a controlled calcination process for fabricating the ceria with large particle size and high appearance density was reported. During precipitation, a certain amount of mineral acid such as nitric acid served as an additive, to adjust the precipitation and crystallization processes of cerium oxalates. An appropriate acidic condition could lead the process into the Oswald ripening stage and made the particles become bigger. Thus, the appearance density of powder was increased. The optimized conditions, such as the temperature, feeding speed, type and concentration of mineral acids, and the concentration of cerium-contained stock solution, were investigated and evaluated.

Application of the concepts of neural network and tree structure in rare earth separations

The concepts of neural network and tree structure are introduced to rare earth separations. The recursive relations and analytical expression for calculating the possible flow sheets and processes are derived in multicomponent systems based on dichotomy. As an example, the application of the concepts is elucidated in detail in a separation of light rare earths containing La, Ce, Pr and Nd in the HEH(EHP)-HCl system. The results show that this method is beneficial to summarizing and classifying the flow sheets and processes in rare earth separations, and is essential to the optimization of separation flow sheets. It can also be applied to the separation into group situations and other similar cases, too.