The carbon-rare earth systems

Gschneidner, K. A.

doi:10.1007/bf02867799

Cited by 54 publications

(8 citation statements)

References 52 publications

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“…However, after the VIM process, the original matrix phase of Nd 2 Fe 14 B disappeared and the phase of rare earth carbide was shown in the patterns of the NdFeBC sat alloy. There are two intermetallic compounds, NdC 2 and Nd 2 C 3 , existing in the Nd–C system. − In the XRD pattern of the as-cast NdFeBC sat alloy, the pattern of neodymium dicarbide was shown clearly. The appearance of α-Fe, Fe 3 C and NdC 2 indicated that the matrix phase of Nd 2 Fe 14 B in the raw materials would dissociate in the VIM process.…”

Section: Resultsmentioning

confidence: 98%

Recovery of Rare Earth Elements from NdFeB Magnet by VIM-HMS Method

Bian

Guo

Jiang

et al. 2016

ACS Sustainable Chem. Eng.

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A novel method to recover rare earth elements (REEs) from NdFeB magnets was developed. This method involves three basic steps, i.e., the vacuum induction melting (VIM) process, the hydrolysis process and the magnetic separation process (HMS). In the VIM process, the NdFeB magnets were melted in a graphite crucible under vacuum (<1 Pa), in which way the rare earth carbides formed by the reaction of REEs and carbon, and the carbon saturated NdFeBCsat alloy was obtained. On the basis of the hydrolysis of rare earth carbides, the REEs were separated from the NdFeBCsat alloy by the reaction of the rare earth carbides phase with water. Thus, the rare earth hydroxides and iron-based metal residues were produced. Magnetic separation was further used to remove the iron residues from the rare earth hydroxides. Through this method, the optimal recovery ratio reached 93%, and the purity of the rare earth hydroxides was as high as 99.7%. Along with the VIM-HMS process, the investigation of NdFeBCsat alloy, the morphology of the rare earth hydroxides and the conversion of rare earth hydroxides to rare earth oxides are also presented in this paper. In this research, the X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductive-coupled plasma spectroscopy (ICP), mass spectrum analyses, CS analyses, magnetic properties analyses and nitrogen physisorption analyses were applied.

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Section: Resultsmentioning

confidence: 98%

Recovery of Rare Earth Elements from NdFeB Magnet by VIM-HMS Method

Bian

Guo

Jiang

et al. 2016

ACS Sustainable Chem. Eng.

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“…Hence, the average of these two results, À(131 ± 19) kJ mol À1 , is chosen to be the recommended value for D f H 0 298 of DyC 2 (s). The entropy of formation of DyC 2 (s) at 298 K was found to be 106 J K À1 mol À1 (using the entropy increment of DyC 2 (s) derived from those of CaC 2 (s), which is close to the compiled data 103.77 J K À1 mol À1 ) of Gschneidner et al [9].…”

Section: Third-law Methodsmentioning

confidence: 92%

“…Anderson et al [7] used a solid state calcium fluoride galvanic cell to determine the thermodynamic data of a number of rare earth carbides including DyC 2 (s) in the temperature range 1033-1263 K. Meschel and Kleppa [8] have determined the enthalpy of formation of DyC 2 (s) using a high-temperature direct synthesis calorimetric technique recently. A compilation of the thermodynamic data of all the rare earth carbides is available in the review article of Gschneidner and Calderwood [9]. Miedema et al [10] have predicted the enthalpy of formation of DyC 2 (s) using a semiempirical model.…”

Section: Introductionmentioning

confidence: 98%

Enthalpy and Gibbs energy of formation of dysprosium dicarbide

Vidhya¹,

Antony²,

Rao³

2006

Journal of Nuclear Materials

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The equilibrium CO(g) pressures have been determined over the univariant three-phase field DyO 1.5 (s)-C(s)-DyC 2 (s) by means of the dynamic effusion MS method, in the temperature range 1360-1590 K. The carbide phase was generated in situ by the carbothermic reduction of the oxide using a quadrupole mass spectrometer, the effusion pressure of carbon monoxide was monitored. The enthalpy of the carbothermic reduction reaction was calculated by second-and thirdlaw methods. By combining the appropriate thermal functions and enthalpies of other constituents from standard thermodynamic tables, the enthalpy of formation of the dicarbide at 298 K has been calculated. The Gibbs energy of formation of the dicarbide in this temperature range has also been calculated. The recommended values of enthalpy and Gibbs energy of formation of DyC 2 (s) at 298 K are À(131 ± 19) kJ mol À1 and À(165 ± 6) kJ mol À1 , respectively.

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“…Lanthanide and actinide elements, to the exception of Pm, form at least one stable carbide, the most common ones being M 2 C 3 and MC 2 . [43] M 2 C 3 carbides are generally stable up to ca. 1500 °C while MC 2 decomposes at ca.…”

Section: Scope Of Applicationmentioning

confidence: 99%