A LANTHANIDE LANTHOLOGY (.pdf) - Davidson Physics

More documents

Recommendations

Info

METALSThe lanthanides, when prepared in the elemental form, are metallic; their basicphysico-chemical data[1] are summarized below. The route chosen to prepare any lanthanidedepends on a blend of economic factors and physical properties such as Ln melting point andultimate desired purity. They can be made[1], in principle, by either• metallothermic reduction, Ln III + M 0 => Ln o + M IIIor• electrolytic reduction, Ln III + 3e => Ln oZ Ln AtomicWt.densityg/cm 3m.pt.°CMETALS, Ln ovaporPressureat m. pt. (torr)b.pt.°C12-coordradiuspmcrystalstructure39 Y 88.906 4.469 1522 2.1 x 10 -3 3338 180.1 hcp57 La 138.905 6.146 918 2.6 x 10 -10 3464 187.9 dhcp58 Ce 140.12 6.770 798 8.5 x 10 –13 3433 182.5 fcc59 Pr 140.907 6.773 931 1.1 x 10 -7 3520 182.8 dhcp60 Nd 144.24 7.008 1021 3.4 x 10 -5 3074 182.1 dhcp61 Pm [145]62 Sm 150.4 7.520 1074 5.8 1794 180.4 rhom63 Eu 151.96 5.244 822 0.91 1527 204.2 bcc64 Gd 157.25 7.901 1313 1.4 x 10 -4 3273 180.1 hcp65 Tb 158.925 8.230 1356 8.6 x 10 -4 3230 178.3 hcp66 Dy 162.50 8.551 1412 0.71 2567 177.4 hcp67 Ho 164.930 8.795 1474 0.54 2700 178.3 hcp68 Er 167.26 9.066 1529 0.37 2868 175.7 hcp69 Tm 168.934 9.321 1545 185 1950 174.6 hcp70 Yb 173.04 6.966 819 19 1196 193.9 fcc71 Lu 174.967 9.841 1663 9.7 x 10 -3 3402 173.5 hcp[1] Preparation and Basic Properties of the Rare Earth Metals, B.J.Beaudry andK.A.Gschneidner, in Handbook on the<strong>Physics</strong> and Chemistry of Rare Earths, ed. K.A.Gschneidner and L.Eyring, Vol. 1, 173,publ. 1979, North Holland3
Metallothermic ProcessesMETALSThe metallothermic approach, widely used for pure element production, is suitable for mostof the Ln series (including mixed-Ln's) and uses as the precursor :• fluoride, chloride, or, for certain elements, oxide.The fluoride is the preferred salt because it can be prepared relatively oxygen-free, is nothygroscopic and a stable end-product slag results. Calcium metal is the reductant most usuallyemployed in industry. For example, Neodymium is produced commercially by mixing a slightexcess of Calcium particles with the fluoride in a Tantalum crucible and heating to initiate theexothermic reaction:• 3 Ca + 2 NdF 3 => 3 CaF 2 + 2 NdThe charge is then held at a high temperature, above the Ln m.pt., to ensure a good separation ofthe lighter immiscible calcium fluoride slag from the heavier Ln metal.Metallothermic reduction of anhydrous chloride precursors has limited applicability. It hasbeen explored as a route to some of the heavy non-volatile Ln's, using Lithium metal vapor as thereductant. The resulting Lithium chloride is distilled off.• LnCl 3 + 3 Li => Ln + 3 LiClOxide reduction is used for the metals, Sm, Eu, Tm and Yb, that have high vapor pressuresaround their melting points, with La metal ( essentially non-volatile at reaction temperatures) as thereductant. The volatile lanthanide is distilled off and collected on a cooled surface, e.g. an invertedTa crucible.• 2 La + Sm 2 O 3 => 2 Sm + La 2 O 3A extension of oxide-reduction is used for the commercial production [2] of thepermanent-magnet intermetallic compound SmCo 5 , a process that avoids the intermediate step ofSm metal production and goes directly to a powder form of the desired metal.• 3 Ca + 10 Co + Sm 2 O 3 => 2 SmCo 5 + 3 CaO[2] C.Herget and H.-G.Domazer, Methods for the Production of Rare Earth-3d Metal Alloys with ParticularEmphasis on the Cobalt Alloys, Goldschmidt Informiert, 1975, 35, 3 (publ. Th.Goldschmidt AG)4
Page 2 and 3: ALANTHANIDELANTHOLOGYPart II, M - Z
Page 6 and 7: Compounds of the perovskite, ABO 3
Page 10: METALSMetallo-thermic oxide-reducti
Page 13 and 14: MONAZITEMonazite, a light-lanthanid
Page 15 and 16: NEODYMIUMNeodymium is the third mos
Page 18 and 19: [2] Preparation, Phase Equilibria,
Page 20 and 21: NOMENCLATURE58 - 71; the term is in
Page 22 and 23: OXALATESAddition of oxalic acid, or
Page 24 and 25: OXIDESCalcination in air for the th
Page 26 and 27: OXIDESFurthermore oxides with Ln IV
Page 28 and 29: OXYCHLORIDESThermal decomposition o
Page 30 and 31: OXYSULFIDESAll the elements of the
Page 32 and 33: PEROVSKITESA very wide range of mat
Page 34 and 35: PHOSPHATESThe LnPO 4 compounds can
Page 36 and 37: PRASEODYMIUMtransport of Pr happens
Page 38 and 39: RESOURCESFor significant resources
Page 40 and 41: RESOURCESSignificant new resources
Page 42 and 43: SAMARIUMSamarium metal is made dire
Page 44 and 45: SILICATESWithin the binary Ln 2 O 3
Page 46 and 47: SOLVENT EXTRACTIONSome text books s
Page 48 and 49: SULFATESLanthanide sulfates can be
Page 50 and 51: SULFIDESThe thermochernistry of CeS
Page 52 and 53: THULIUMThulium, the rarest of the "
Page 54 and 55: TITANATES, TITANIUM DIOXIDELanthani
Page 56 and 57: YTTERBIUMIn broad chemical behavior
Page 58 and 59:
YTTRIUMCompoundIdealFormulaFormula
Page 60 and 61:
YTTRIUM OXIDEThe very stable oxide,
Page 62 and 63:
YTTRIUM OXIDEThe widespread introdu
show all

A LANTHANIDE LANTHOLOGY (.pdf) - Davidson Physics

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?