Vaporization of some rare-earth dicarbides

Faircloth, R.L.; Flowers, R.H.; Pummery, F.C.W.

doi:10.1016/0022-1902(68)80476-2

Cited by 51 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But it is unclear why several authors reported a tetragonal modification at ambient conditions, 8,11 which could not be repeated by others. 9 Similar observations were made for CaC 2 . For many years a tetragonal modification was reported being stable at ambient conditions.…”

Section: Discussionsupporting

confidence: 73%

“…These results could not be repeated in a later work, and a lower symmetry structure was suggested. 9 As the reported unit-cell volume of EuC 2 is much larger than those of the other RE 3þ dicarbides, it was concluded that Eu 2þ ions were present and that the carbide was wholly ionic. 151 Eu M€ ossbauer spectra corroborated these assumptions, 10 although the reported lattice parameters of the sample under investigation differed largely from those reported earlier.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structural Phase Transitions in EuC₂

et al. 2009

View full text Add to dashboard Cite

Pure EuC(2), free of EuO impurities, was obtained by the reaction of elemental europium with graphite at 1673 K. By means of synchrotron powder diffraction experiments, the structural behavior was investigated in the temperature range from 10 to 1073 K. In contrast to former results, EuC(2) crystallizes in the ThC(2) type structure (C2/c, Z = 4) at room temperature. A tetragonal modification (I4/mmm, Z = 2) is only observed in a very small temperature range just below the transition to a cubic high-temperature modification (Fm3m, Z = 4) at 648 K. DTA/TG investigations confirm these results. According to Raman spectroscopy, EuC(2) contains C(2)(2-) ions (nu(C[triple bond]C) = 1837 cm(-1)). The divalent character of Eu is confirmed by the results of magnetic susceptibility measurements and (151)Eu Mossbauer spectroscopy. In these measurements a transition to a ferromagnetic state with T(C) = 15 K is observed, which is in reasonable agreement with literature data. Above T(C) EuC(2) is a semiconductor according to measurements of the electric resistivity vs temperature, again in contrast to former results. Around T(C) a sharp maximum of the electric resistivity vs temperature curve was observed, which collapses on applying external magnetic fields. The observed CMR effect (colossal magnetoresistance) is much stronger than that reported for other EuC(2) samples in the literature. These investigations explicitly show the influence of sample purity on the physical and even structural properties of EuC(2).

show abstract

Section: Discussionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Structural Phase Transitions in EuC₂

et al. 2009

View full text Add to dashboard Cite

show abstract

“…where k0 is the rate of radiative decay (phosphorescence) and fci is the rate of radiationless crossing to the ground state. The summation term includes all quenching (11) G. Porter and M. W. Windsor, Proc. Roy.…”

Section: Resultsmentioning

confidence: 99%

Second triplet level of 1,5-dichloroanthracene in fluid solutions

Dixon¹,

Roberts²

1971

J. Phys. Chem.

View full text Add to dashboard Cite

“…21 Decomposition of neodymium dicarbide has previously been described in literature and was found to result in formation of elemental Nd and carbon. 34,35 According to the literature, decomposition of NdC 2 has occurred under vacuum conditions, which differs from the atmospheric pressure inert gas used in the current experiments. The proposed reaction mechanism based on carbothermic reduction of Nd 2 O 3 and subsequent decomposition of both Nd 2 O 2 C 2 and NdC 2 , forming Cu−Nd intermetallics, is illustrated in Scheme 1.…”

Section: ■ Discussionmentioning

confidence: 99%

Formation of Copper–Neodymium Intermetallic Compounds by Carbothermic Reduction of Neodymium Oxide in the Presence of Copper

Ødegård

Tranell

2018

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Carbothermic reduction of neodymium(III) oxide (Nd 2 O 3 ) was performed by arc melting and in a graphite resistance furnace, using copper as a solvent metal. Successful carbothermic reduction was evident by formation of copper−neodymium intermetallics, where predominant phases were found to be Cu 6 Nd and Cu 5 Nd. The reduction reaction is proposed to be caused by thermal decomposition of neodymium oxide carbide (Nd 2 O 2 C 2 ) forming a molten mixture of neodymium(III) oxide and neodymium dicarbide (NdC 2 ) upon release of carbon monoxide (CO(g)), where subsequent decomposition of neodymium dicarbide was facilitated by a reduction in activity of formed elemental neodymium species solvated in molten copper. Addition of carbon in excess of neodymium oxide carbide stoichiometry was found to correlate with increased concentration of neodymium in copper, likely caused by an increase in concentration of neodymium dicarbide. 51 energy efficient, high productivity methods of producing and 52 recycling Nd are sought. 53 Due to the high affinity between rare earth elements and 54 carbon, forming a range of stable carbides and oxide carbides, 55 carbothermic reduction as a method of producing the 56 corresponding elemental compounds has been considered to 57 be difficult at best. 9 From available literature, several accounts 58 of carbothermic reduction with respect to elements that are 59 known to form stable carbides were found, among these, the 60 rare earths are represented. Some methods mentioned are 61 reduction by dissolving into suitable solvent metals, reaction 62 between carbides, and an element forming a more stable 63 carbide, formation of nitrides then vacuum decomposition of 64 said nitrides in solution with suitable solvent metals, etc. 10−18 65 Examples from literature reveals, among others, a patent by 66 Staggers that describes carbothermic reduction of rare earth 67 elements by formation of rare earth silicide alloys. 18 The 68 method apparently allows for the simultaneous carbothermic 69 reduction of rare earth oxides, especially cerium oxide (CeO 2 ) 70 along with alkaline earth oxides such as barium oxide (BaO), 71 calcium oxide (CaO), and strontium oxide (SrO) in the 72 presence of silica (SiO 2 ) and elemental iron (Fe) at elevated 73 temperatures, forming both rare earth and alkaline earth

show abstract

Vaporization of some rare-earth dicarbides

Cited by 51 publications

References 12 publications

Structural Phase Transitions in EuC₂

Structural Phase Transitions in EuC₂

Second triplet level of 1,5-dichloroanthracene in fluid solutions

Formation of Copper–Neodymium Intermetallic Compounds by Carbothermic Reduction of Neodymium Oxide in the Presence of Copper

Contact Info

Product

Resources

About

Vaporization of some rare-earth dicarbides

Cited by 51 publications

References 12 publications

Structural Phase Transitions in EuC2

Structural Phase Transitions in EuC2

Second triplet level of 1,5-dichloroanthracene in fluid solutions

Formation of Copper–Neodymium Intermetallic Compounds by Carbothermic Reduction of Neodymium Oxide in the Presence of Copper

Contact Info

Product

Resources

About

Structural Phase Transitions in EuC₂

Structural Phase Transitions in EuC₂