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Wang L.,Anhui University | Meng F.,Anhui University | Meng F.,Dalian University of Technology | Li K.,Peking University | Lu F.,Baotou Research Institute of Rare Earths
Applied Surface Science | Year: 2013

CeO2 nanopoles have been successfully synthesized by a hydrothermal method using CeCl3·7H2O as cerium source, NaOH as mineralizer, and ethylenediamine as complexant. The pole-like nano-CeO2 was examined by XRD, TEM, XPS, UV-vis, PL, and Raman scattering. The results show that the crystallinity of the nanopoles is not so good, and the main valence of cerium is +4. The estimated direct band gaps are 3.014, 3.099, 2.931, and 2.927 eV for the samples synthesized within 2, 18, 50, and 100 h, respectively. These band gaps are smaller than bulk CeO2, oxygen vacancies and Ce3+ ions result in an effective red shifting of the band gap. The visible luminescence exhibits similar emission peaks of room temperature photoluminescence and the emission intensity increases with the increase of concentration of oxygen vacancies and Ce3+ ions. © 2013 Elsevier B.V. All rights reserved.


Sun N.K.,Shenyang Ligong University | Guo J.,Shenyang Ligong University | Zhao X.G.,CAS Shenyang Institute of Metal Research | Si P.Z.,China Jiliang University | And 2 more authors.
Applied Physics Letters | Year: 2015

La(Fe, Si)13 hydride is regarded as one of the most promising room-temperature refrigerants. However, to use the alloys in an active magnetic regenerator machine, it is vital to prepare thin refrigerants. In this work, a high H2 gas pressure of 50 MPa was employed to suppress the desorption of hydrogen atoms during the sintering process of plate-shaped La0.5Pr0.5Fe11.4Si1.6 hydrides. At 330 K, a high-density sintered thin plate shows a large magnetic-entropy change ΔSm of 15.5 J/kg K (106 mJ/cm3K) for a field change of 2 T. The volumetric ΔSm is almost twice as large as that of bonded La(Fe,Si)13 hydrides. Favorably, hysteresis is almost absent due to the existence of micropores with a porosity of 0.69% which has been analyzed with high-resolution X-ray microtomography. © 2015 AIP Publishing LLC.


Fitchorov T.I.,Northeastern University | Bennett S.,Northeastern University | Jiang L.,Baotou Research Institute of Rare Earths | Zhang G.,Baotou Research Institute of Rare Earths | And 3 more authors.
Acta Materialia | Year: 2014

The temperature stability of Fe81Ga19Tbx (x = 0.3) and Fe81Ga19 (i.e. Galfenol) alloys is investigated over a temperature range from 10 to 1000 K. High-temperature measurement of magnetization indicates that Tb-doped FeGa results in a Curie temperature rise of ∼150 K, while saturation magnetization and magnetostrictive coefficient increase by 7% and 2.5-fold, respectively, compared to the parent Fe81Ga19 alloy. It is noticed that Fe 81Ga19Tbx (x = 0.3) alloy not only gives rise to a noticeable stabilization of magnetic moment below room temperature, but also presents a dramatic decrease in temperature coefficient of magnetostriction by ∼30%. Most interestingly, a large negative magnetoresistance (MR) of -25% at 10 kOe is observed at low temperature, ∼75 K for a magnetostrictive Fe81Ga19 alloy. Ferromagnetic and antiferromagnetic behaviors occur simultaneously in the temperature range conducive to a large MR. Furthermore, the large MR is also assumed to relate to a weak spin glass phase of the alloy observed at cryogenic temperatures and confirmed by ac susceptibility measurements. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Jiang L.,Baotou Research Institute of Rare Earths | Yang J.,Baotou Research Institute of Rare Earths | Hao H.,Baotou Research Institute of Rare Earths | Zhang G.,Baotou Research Institute of Rare Earths | And 5 more authors.
Applied Physics Letters | Year: 2013

We present the effects of terbium additives upon the microstructure and magnetic properties of Fe83Ga17Tbx alloys (x = 0, 0.2, 0.4, 0.6, and 0.8), prepared by vacuum electric arc-melting and directional solidification techniques. Experiments indicate that small amounts of terbium more than double the saturation magnetostriction of a [110] textured Fe83Ga17 alloy with λ = 72 × 10-6 and lower the magnetostriction saturation field. The pronounced increase in magnetostriction stems from the appearance of [100] texture in polycrystalline alloys. It is verified that [110] and [100] textures are enhanced by the introduction of terbium atoms preferentially residing in a Tb-rich intergranular phase. © 2013 AIP Publishing LLC.


Chen Y.,Northeastern University | Gillette S.M.,Northeastern University | Fitchorov T.,Northeastern University | Jiang L.,Baotou Research Institute of Rare Earths | And 6 more authors.
Applied Physics Letters | Year: 2011

A miniature, quasi one dimensional, magnetic field sensor based on magnetoelectric coupling is presented. The magnetoelectric sensor makes use of the d31 coupling mode between a piezoelectric lead zirconate titanate tube and FeNi magnetostrictive wire. The sensors demonstrate high sensitivity, high signal-to-noise ratio, and low noise floor at zero DC magnetic bias field and at low frequency resulting in smaller, lower power consumption, and volumetric efficiency. Experiments indicate a zero bias field sensitivity of 16.5 mV/Oe at 100 Hz stemming from a magnetoelectric coefficient of 1.65 V/cm-Oe. The results are quantitatively described by a theoretical model of laminate composites. © 2011 American Institute of Physics.


Phan T.-L.,Chungbuk National University | Zhang Y.D.,Baotou Research Institute of Rare Earths | Yang D.S.,Chungbuk National University | Nghia N.X.,Vietnam Academy of Science and Technology | And 3 more authors.
Applied Physics Letters | Year: 2013

Though ZnO is known as a diamagnetic material, recent studies have revealed that its nanostructures can be ferromagnetic (FM). The FM origin has been ascribed to intrinsic defects. This work shines light on an alternate method based on mechanical milling to induce defect-related ferromagnetism in ZnO nanoparticles (NPs) from initial diamagnetic ZnO powders. Our idea is motivated by the fact that mechanical milling introduces more defects to a ground material. We point out that the FM order increases with increasing the density of defects in ZnO NPs. The experimental results obtained from analyzing X-ray absorption, electron spin resonance, and Raman scattering spectra demonstrate that the ferromagnetism in ZnO NPs is due to intrinsic defects mainly related to oxygen and zinc vacancies. Among these, zinc vacancies play a decisive role in introducing a high FM order in ZnO NPs. © 2013 American Institute of Physics.


Jiang M.,Northeastern University China | Su X.,Northeastern University China | Su X.,Baotou Research Institute of Rare Earths | Li H.,Northeastern University China | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

Phase equilibria in the Mg-rich Mg-Cu-Y system at 300, 400 and 450 C have been experimentally investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results show that a long-period stacking ordered (LPSO) phase 14H is stable in the Mg-Cu-Y system, which is the only one ternary intermetallic compound that gets a thermodynamic equilibrium with the a-Mg phase. The equilibrium 14H phase has a very limited solid solution range, and can be nearly regarded as a ternary stoichiometric compound with a formulae as Mg91Cu4Y5. The thermal stability of the 14H phase in the Mg-Cu-Y system has been well studied, which shows that the 14H phase disappears varying from 442 C to 490 C depending on the alloy composition. The isothermal sections of the Mg-rich Mg-Cu-Y system at 300, 400 and 450 C have been finally established, and moreover, a quasi-peritectic reaction L + α-Mg ↠14H + Mg2Cu has been determined occurring at 442 C with an estimated liquid composition of Mg77Cu18Y5. © 2014 Elsevier B.V. All rights reserved.


Liu B.,Inner Mongolia University | Li C.,Inner Mongolia University | Zhang Y.,Inner Mongolia University | Liu Y.,Inner Mongolia University | And 4 more authors.
Applied Catalysis B: Environmental | Year: 2012

A colloidal crystal template method coupled with a precursor complexion process was developed to create three-dimensionally ordered macroporous (3DOM) Au/CeO 2 catalyst. The resultant Au/CeO 2 catalyst possesses well-defined 3DOM structure, and shows enhanced catalytic performance for formaldehyde (HCHO) oxidation with 100% HCHO conversion at ∼75°C. The catalytic mechanism of HCHO catalytic oxidation over 3DOM Au/CeO 2 catalyst was systematically investigated by means of gas chromatograph (GC), H 2-temperature programmed reduction (H 2-TPR), temperature programmed surface reaction (TPSR), CO 2-temperature programmed desorption (TPD), and Fourier transform infra-red (FT-IR) spectroscopy. GC results indicate that HCOOH intermediate is generated during HCHO catalytic oxidation. TPD and TPSR tests show that the weak absorption ability of CO 2 over 3DOM Au/CeO 2 catalyst and the existence of Au active species in ionic and metallic states in 3DOM Au/CeO 2 catalyst largely improve the catalytic activity, favoring the enhanced HCHO catalytic oxidation. FT-IR tests prove that the carbonate and hydrocarbonate formed on the surface of 3DOM Au/CeO 2 catalyst during HCHO catalytic oxidation may account for its deactivation. Based on the above investigation, a new catalytic mechanism of enhanced HCHO catalytic oxidation over 3DOM Au/CeO 2 catalyst is proposed. The mechanism may afford the scientific guidance for preparing high efficiency oxide supported noble metal catalysts and present a solution for solving their deactivation problem. © 2011 Elsevier B.V.


Chen Y.-X.,Baotou Research Institute of Rare Earths
Chinese Rare Earths | Year: 2014

This paper summarizes the development process of using fluoride salt electrolysis to produce rare earth metals at home and abroad, analyses the researches on physico-chemical properties and electrochemical properties of rare-earth fluoride electrolyte and reviews study progress of numerical simulation on the process.


Kong F.,Baotou Research Institute of Rare Earths
Electrochimica Acta | Year: 2012

In this paper, micrometer Co 3O 4 materials are synthesized via a method of chemical synthesis in combination with calcinations. The effect of calcination temperature on the morphology, structure and catalytic performance as air/oxygen electrode materials are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy and electrochemical techniques. The SEM observation reveals that the morphology of the Co 3O 4 products changes to a beadlike shape from the rod shape after calcinated at temperature of 700 °C. The XRD measurements show that the both morphology Co 3O 4 products exhibit a cubic phase of Co 3O 4 spinel with a space group of Fd3m. But the beadlike Co 3O 4 product has better crystallinity. The electrochemical measurements show that the beadlike Co 3O 4 material has better active properties for electrochemical O 2 reduction and O 2 generation reactions. Also it exhibits the bi-functional performance in the oxygen-diffusion electrodes and has potential applications in rechargeable metal-air batteries and regenerative fuel cells. © 2012 Elsevier Ltd. All rights reserved.

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