稀土金属的物理性质

TABLE 1. Data for the Trivalent Ions of the Rare Earth Elements Rare earth Symbol Atomic no. Atomic wt.a Electronic configuration for R3+ Spectroscopic ground state symbol No. 4f electrons S L J Scandium Sc 21 44.955910 0 — — — — Yttrium Y 39 88.90585 0 — — — — Lanthanum La 57 138.9055 0 — — — — Cerium Ce 58 140.115 1 1/2 3 5/2 2F 5/2 Praseodymium Pr 59 140.90765 2 1 5 4 3H 4 Neodymium Nd 60 144.24 3 3/2 6 9/2 4I 9/2 Promethium Pm 61 (145) 4 2 6 4 5I 4 Samarium Sm 62 150.36 5 5/2 5 5/2 6H 5/2 Europium Eu 63 151.965 6 3 3 0 7F 0 Gadolinium Gd 64 157.25 7 7/2 0 7/2 8S 7/2 Terbium Tb 65 158.92534 8 3 3 6 7F 6 Dysprosium Dy 66 162.50 9 5/2 5 15/2 6H 15/2 Holmium Ho 67 164.93032 10 2 6 8 5I 8 Erbium Er 68 167.26 11 3/2 6 15/2 4I 15/2 Thulium Tm 69 168.93421 12 1 5 6 3H 6 Ytterbium Yb 70 173.04 13 1/2 3 7/2 2F 7/2 Lutetium Lu 71 174.967 14 — — — — Note: For additional information, see Goldschmidt, Z.B., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978; DeLaeter, J.R., and Heumann, K.G., J. Phys. Chem. Ref. Data, 20, 1313 , 1991; Pure Appl. Chem., 66, 2423, 1994. a 1993 standard atomic weights. TABLE 2. Crystallographic Data for the Rare Earth Metals at 24°C (297 K) or Below Rare earth metal Crystal structurea Lattice constants (Å) Metallic radius CN = 12 (Å) Atomic volume (cm3/mol) Density (g/cm3)a o b o c o αSc hcp 3.3088 — 5.2680 1.6406 15.039 2.989 αY hcp 3.6482 — 5.7318 1.8012 19.893 4.469 αLa dhcp 3.7740 — 12.171 1.8791 22.602 6.146 αCeb fcc 4.85b — — 1.72b 17.2b 8.16b βCe dhcp 3.6810 — 11.857 1.8321 20.947 6.689 γCec fcc 5.1610 — — 1.8247 20.696 6.770 αPr dhcp 3.6721 — 11.8326 1.8279 20.803 6.773 αNd dhcp 3.6582 — 11.7966 1.8214 20.583 7.008 αPm dhcp 3.65 — 11.65 1.811 20.24 7.264 αSm rhombd 3.6290d — 26.207 1.8041 20.000 7.520 Eu bcc 4.5827 — — 2.0418 28.979 5.244 αGd hcp 3.6336 — 5.7810 1.8013 19.903 7.901 α′Tbe ortho 3.605e 6.244e 5.706e 1.784e 19.34e 8.219e αTb hcp 3.6055 — 5.6966 1.7833 19.310 8.230 α′Dyf ortho 3.595f 6.184f 5.678f 1.774f 19.00f 8.551f αDy hcp 3.5915 — 5.6501 1.7740 19.004 8.551 Ho hcp 3.5778 — 5.6178 1.7661 18.752 8.795 Er hcp 3.5592 — 5.5850 1.7566 18.449 9.066 Tm hcp 3.5375 — 5.5540 1.7462 18.124 9.321 αYbg hcp 3.8799g — 6.3859g 1.9451g 25.067g 6.903g βYb fcc 5.4848 — — 1.9392 24.841 6.966 Lu hcp 3.5052 — 5.5494 1.7349 17.779 9.841 Note: For additional information, see Gschneidner, K.A., Jr. and Calderwood, F.W., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 8, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1986; Gschneidner, K.A., Jr., Pecharsky, V.K., Cho, Jaephil and Martin, S.W., Scripta Mater., 1996, to be published. a hcp = hexagonal close-packed; P6 3 /mmc, hP2, A3, Mg-type; dhcp = double-c hexagonal close-packed; P6 3 /mmc, hP4, A3, αLa-type; fcc = face-centered cubic; Fm3 m, cF4, A1, Cu-type; rhomb = rhombohedral; R3 m, hR3, αSm-type; bcc = body-centered cubic; Im3 m, cI2, A2, W-type; ortho = orthorhombic; Cmcm, oC4, α Dy-type. b At 77 K (–196°C). c Equilibrium room temperature (standard state) phase. d Rhombohedral is the primitive cell. Lattice parameters given are for the nonprimitive hexagonal cell. d At 220 K (–53°C). f At 86 K (–187°C). g At 23°C. PHYSICAL PROPERTIES OF THE RARE EARTH METALS K.A. Gschneidner, Jr. 4-119 Section4.indb 119 5/2/05 9:24:50 AM TABLE 3. Crystallographic Data for Rare Earth Metals at High Temperature Rare earth metal Structure Lattice parameter (Å) Metallic radius Atomic volume (cm3/mol) Density (g/ cm3)Temp. (°C) CN = 8 (Å) CN = 12 (Å) βSc bcc 3.73 (est.) 1337 1.62 1.66 15.6 2.88 βY bcc 4.10a 1478 1.78 1.83 20.8 4.28 βLa fcc 5.303 325 — 1.875 22.45 6.187 γLa bcc 4.26 887 1.84 1.90 23.3 5.97 δCe bcc 4.12 757 1.78 1.84 21.1 6.65 βPr bcc 4.13 821 1.79 1.84 21.2 6.64 βNd bcc 4.13 883 1.79 1.84 21.2 6.80 βPm bcc 4.10 (est.) 890 1.78 1.83 20.8 6.99 βSm hcp a = 3.6630 450b — 1.8176 20.450 7.353 c = 5.8448 γSm bcc 4.10 (est.) 922 1.77 1.82 20.8 7.25 βGd bcc 4.06 1265 1.76 1.81 20.2 7.80 βTb bcc 4.07a 1289 1.76 1.81 20.3 7.82 βDy bcc 4.03a 1381 1.75 1.80 19.7 8.23 γYb bcc 4.44 763c 1.92 1.98 26.4 6.57 Note: The rare earths Eu, Ho, Er, Tm, and Lu are monomorphic. For additional information, see Gschneidner, K.A., Jr. and Calderwood, F.W., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 8, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1986, 1. a Determined by extrapolation to 0% solute of a vs. composition data for R-Mg alloys at 24°C and corrected for thermal expansion to temperature given. b The hcp phase was stabilized by impurities and the temperature of measurement was below the equilibrium transition temperature (see Table 4). c The bcc phase was stabilized by impurities and the temperature of measurement was below the equilibrium transition temperature (see Table 4). TABLE 4. High Temperature Transition Temperatures and Melting Point of Rare Earth Metals Rare earth metal Transition I (α – β)a Transition II (β – γ)a Melting point (C°)Temp. (°C) Phases Temp. (C°) Phases Sc 1337 hcp  bcc — — 1541 Y 1478 hcp  bcc — — 1522 Lab 310 dhcp  fcc 865 fcc  bcc 918 Cec,d 139 dhcp  fcc (β - γ) 726 fcc  bcc (γ - δ) 798 Pr 795 dhcp  bcc — — 931 Nd 863 dhcp  bcc — — 1021 Pm 890 dhcp  bcc — — 1042 Sme 734 rhom  hcp 922 hcp  bcc 1074 Eu — — — — 822 Gd 1235 hcp  bcc — — 1313 Tb 1289 hcp  bcc — — 1356 Dy 1381 hcp  bcc — — 1412 Ho — — — — 1474 Er — — — — 1529 Tm — — — — 1545 Yb 795 fcc  bcc (β - γ) — — 819 Lu — — — — 1663 Note: For additional information, see Gschneidner, K.A., Jr. and Calderwood, F.W., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 8, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1986; Gschneidner, K.A., Jr., Pecharsky, V.K., Cho, Jaephil and Martin, S.W., Scripta Mater., 34, 1717, 1996. a For all the transformations listed, unless otherwise noted. b On cooling, fcc → dhcp (β → α), 260°C. c The β  γ equilibrium transition temperature is 10 ± 5°C. d On cooling, fcc → dhcp (γ → β), –16°C. e On cooling, hcp → rhomb (β → α), 727°C. TABLE 5. Low Temperature Transition Temperatures of the Rare Earth Metals Rare earth metal Cooling Rare earth metal Heating Transformation °C K Transformation °C K Ce γ → βa –16 257 Ce α → β –148 125 γ → α –172 101 α → β + γ –104 169 β → α –228 45 β → γa 139 412 Tb α → α′ –53 220 Yb α → β 7 280 Dy α → α′ –187 86 Yb β → α –13 260 Note: For additional information, see Beaudry, B.J. and Gschneidner, K.A., Jr., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 173; Koskenmaki, D.C. and Gschneidner, K.A., Jr., 1978, in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 337; Gschneidner, K.A., Jr., Pecharsky, V.K., Cho, Jaephil and Martin, S.W., Scripta Mater., 34, 1717, 1996. a The β  γ equilibrium transition temperature is 10 ± 5°C (283 ± 5K). 4-120 Physical Properties of the Rare Earth Metals Section4.indb 120 5/2/05 9:24:52 AM TABLE 6. Heat Capacity, Standard Entropy, Heats of Transformation, and Fusion of the Rare Earth Metals Rare earth metal Heat capacity at 298 K (J/mol K) Standard entropy S° 298 (J/mol K) Heat of transformation (kJ/mol) Heat of fusion (kJ/mol)trans. 1 ∆H tr 1 trans. 2 ∆H tr 2 Sc 25.5 34.6 α  β 4.00 — — 14.1 Y 26.5 44.4 α  β 4.99 — — 11.4 La 27.1 56.9 α  β 0.36 β  γ 3.12 6.20 Ce 26.9 72.0 β  γ 0.05 γ  δ 2.99 5.46 Pr 27.2 73.2 α  β 3.17 — — 6.89 Nd 27.5 71.5 α  β 3.03 — — 7.14 Pm 27.3a 71.6a α  β 3.0a — — 7.7a Sm 29.5 69.6 α  β 0.2a β  γ 3.11 8.62 Eu 27.7 77.8 — — — — 9.21 Gd 37.0 68.1 α  β 3.91 — — 10.0 Tb 28.9 73.2 α  β 5.02 — — 10.79 Dy 27.7 75.6 α  β 4.16 — — 11.06 Ho 27.2 75.3 — — — — 17.0a Er 28.1 73.2 — — — — 19.9 Tm 27.0 74.0 — — — — 16.8 Yb 26.7 59.9 β  γ 1.75 — — 7.66 Lu 26.9 51.0 — — — — 22a Note: For additional information, see Hultgren, R., Desai, P.D., Hawkins, D.T., Gleiser, M., Kelley, K.K., and Wagman, D.D., Selected Values of the Thermodynamic Properties of the Elements, ASM International, Metals Park, Ohio, 1973; Wagman, D.D., Evans, W.H., Parker, V.B., Schumm, R.H., Halow, I., Bailey, S.M., Churney, K.L., and Nuttall, R.L., The NBS Tables of Chemical Thermodynamic Properties, J. Phys. Chem. Ref. Data, Vol. 11, Suppl 2, 1982; Amitin, E.B., Bessergenev, W.G., Kovalevskaya, Yu. A., and Paukov, I.E., J. Chem. Thermodyn., 15, 181, 1983; Amitin, E.B., Bessergenev, W.G., Kovalevskaya, Yu. A., and Paukov, I.E., J. Chem. Thermodyn., 15, 181, 1983. a Estimated. TABLE 7. Vapor Pressures, Boiling Points, and Heats of Sublimation of Rare Earth Metals Rare earth metal Temperature in °Ca for a vapor pressure of Boiling pointa (°C) Heat of sublimation at 25°C (kJ/mol) 10–8 atm (0.001 Pa) 10–6 atm (0.101 Pa) 10–4 atm (10.1Pa) 10–2 atm (1013 Pa) Sc 1036 1243 1533 1999 2836 377.8 Y 1222 1460 1812 2360 3345 424.7 La 1301 1566 1938 2506 3464 431.0 Ce 1290 1554 1926 2487 3443 422.6 Pr 1083 1333 1701 2305 3520 355.6 Nd 955 1175 1500 2029 3074 327.6 Pm — — — — 3000b 348b Sm 508 642 835 1150 1794 206.7 Eu 399 515 685 964 1529 175.3 Gd 1167 1408 1760 2306 3273 397.5 Tb 1124 1354 1698 2237 3230 388.7 Dy 804 988 1252 1685 2567 290.4 Ho 845 1036 1313 1771 2700 300.8 Er 908 1113 1405 1896 2868 317.1 Tm 599 748 964 1300 1950 232.2 Yb 301 400 541 776 1196 152.1 Lu 1241 1483 1832 2387 3402 427.6 Note: For additional information, see Hultgren, R., Desai, P.D., Hawkins, D.T., Gleiser, M., Kelley, K.K., and Wagman, D.D., Selected Values of the Thermodynamic Properties of the Elements, ASM International, Metals Park, Ohio, 1973; Beaudry, B.J. and Gschneidner, K.A., Jr., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 173. a International Temperature Scale of 1990 (ITS-90) values. b Estimated. Physical Properties of the Rare Earth Metals 4-121 Section4.indb 121 5/2/05 9:24:53 AM TABLE 8. Magnetic Properties of the Rare Earth Metals Rare earth metal Effective magnetic moment Easy axis Néel temp. T N (K) Curie temp. T C (K) θ p (K) χ A × 106 at 298 K (emu/mol) Paramagnetic at ~298 K Ferromagnetic at ~0 K c ⊥c Polycryst. or avg.Theorya Obs. Theoryb Obs. Hex sites Cubic sites αSc 295.2 — — — — — — — — — — — αY 187.7 — — — — — — — — — — — αLa 95.9 — — — — — — — — — — — βLa 105 — — — — — — — — — — — γCe 2,270 2.54 2.52 2.14 — — — 14.4 — — — –50 βCe 2,500 2.54 2.61 2.14 — — 13.7 12.5 — — — –41 αPr 5,530 3.58 3.56 3.20 2.7c a 0.03 — — — — 0 αNd 5,930 3.62 3.45 3.27 2.2c b 19.9 7.5 — 0 5 3.3 αPm — 2.68 — 2.40 — — — — — — — — αSm 1,278d 0.85 1.74 0.71 0.5c a 109 14.0 — — — — Eu 30,900 7.94 8.48 7.0 5.9 <110> — 90.4 — — — 100 αGd 185,000e 7.94 7.98 7.0 7.63 30° to c — — 293.4 317 317 317 αTb 170,000 9.72 9.77 — — — 230.0 — — 195 239 224 α′Tb — — — 9.0 9.34 b — — 219.5 — — — αDy 98,000 10.64 10.83 — — — 180.2 — — 121 169 153 α′Dy — — — 10.0 10.33 a — — 90.5g — — — Ho 72,900 10.60 11.2 10.0 10.34 b 132 — 19.5 73.0 88.0 83.0 Er 48,000 9.58 9.9 9.0 9.1 30° to c 85 — 18.7 61.7 32.5 42.2 Tm 24,700 7.56 7.61 7.0 7.14 c 58 — 32.0 41.0 –17.0 2.3 βYb 67d — — — — — — — — — — — Lu 182.9 — — — — — — — — — — — Note: For additional information, see McEwen, K.A., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North- Holland Physics, Amsterdam, 1978, 411; Legvold, S., in Ferromagnetic Materials, Vol. 1, Wohlfarth, E.P., Ed., North-Holland Physics, Amsterdam, 1980, 183; Pecharsky, V.K., Gschneidner, K.A., Jr. and Fort, D., Phys. Rev. B, 47, 5063, 1993; Pecharsky, V.K., Gschneidner, K.A., Jr. and Fort, D., 1996, to be published; Steward, A.M. and Collocott, S.J., J. Phys.: Condens. Matter, 1, 677, 1988. a g[J(J + 1)]1/2. b gJ. c At 38 T and 4.2 K. d At 290 K. e At 350 K. g On cooling T C = 89.6 K and on warming T C = 91.5 K. TABLE 9. Room Temperature Coefficient of Thermal Expansion, Thermal Conductivity, Electrical Resistance, and Hall Coefficient Rare earth metal Expansion (α i × 106) (°C–1) Thermal conductivity (W/cm K) Electrical resistance (µΩ⋅cm) Hall coefficient (R i × 1012) (V⋅cm/A⋅Oe) α a α c α poly ρ a ρ c ρ poly R a R c R poly αSc 7.6 15.3 10.2 0.158 70.9 26.9 56.2a — — –0.13 αY 6.0 19.7 10.6 0.172 72.5 35.5 59.6 –0.27 –1.6 — aLa 4.5 27.2 12.1 0.134 — — 61.5 — — –0.35 bCe — — — — — — 82.8 — — — γCe 6.3 — 6.3 0.113 — — 74.4 — — +1.81 αPr 4.5 11.2 6.7 0.125 — — 70.0 — — +0.709 αNd 7.6 13.5 9.6 0.165 — — 64.3 — — +0.971 αPm 9b 16b 11b 0.15b — — 75b — — — αSm 9.6 19.0 12.7 0.133 — — 94.0 — — –0.21 Eu 35.0 — 35.0 0.139b — — 90.0 — — +24.4 αGd 9.1c 10.0c 9.4c 0.105 135.1 121.7 131.0 –10 –54 –4.48d αTb 9.3 12.4 10.3 0.111 123.5 101.5 115.0 –1.0 –3.7 — αDy 7.1 15.6 9.9 0.107 111.0 76.6 92.6 –0.3 –3.7 — Ho 7.0 19.5 11.2 0.162 101.5 60.5 81.4 +0.2 –3.2 — Er 7.9 20.9 12.2 0.145 94.5 60.3 86.0 +0.3 –3.6 — Tm 8.8 22.2 13.3 0.169 88.0 47.2 67.6 — — –1.8 βYb 26.3 — 26.3 0.385 — — 25.0 — — +3.77 Lu 4.8 20.0 9.9 0.164 76.6 34.7 58.2 +0.45 –2.6 –0.535 Note: For additional information, see Beaudry, B. J. and Gschneidner, K.A., Jr., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 173; McEwen, K.A., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 411. a Calculated from single crystal values. b Estimated. c At 100°C. d At 77°C. 4-122 Physical Properties of the Rare Earth Metals Section4.indb 122 5/2/05 9:24:54 AM TABLE 10. Electronic Specific Heat Constant (γ), Electron-Electron (Coulomb) Coupling Constant (µ*), Electron-Phonon Coupling Constant (λ), Debye Temperature at 0 K(θ D ), and Superconducting Transition Temperature Rare earth metal γ (mJ/mol⋅K2) µ* λ θ D (K) from Superconducting temperature (K)Heat capacity Elastic constants αSc 10.334 0.16 0.30 345.3 — 0.050a αY 7.878 0.15 0.30 244.4 258 1.3b αLa 9.45 0.08 0.76 150 154 5.10 βLa 11.5 — — 140 — 6.00 αCe 12.8 — — 179 — 0.022c αPr 20 — 1.07d 155e 153 — αNd f — 0.86d 157e 163 — αPm — — — 159e — — αSm 8.1 ± 1.5g — 0.81d 162e,f 169 — Eu f — — f 118 — αGd 4.48 — 0.30 169 182 — α′Tb 3.71 — 0.34d 169.6 177 — α′Dy 4.9 — 0.32d 192 183 — Ho 2.1 — 0.30d 175e 190 — Er 8.7 — 0.33d 176.9 188 — Tm f — 0.36d 179e 200 — αYb 3.30 — — 117.6 118 — βYb 8.36 — — 109 — — Lu 8.194 0.14 0.31 183.2 185 0.022h Note: For additional information, see Sundström, L.J., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr., and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 379; Scott, T., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 591; Probst, C. and Wittig, J., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North-Holland Physics, Amsterdam, 1978, 749; Tsang, T.-W.E., Gschneidner, K.A., Jr., Schmidt, F.A., and Thome, D.K., Phys. Rev., B, 31, 235, 1985; Collocott, S.J., Hill, R.W. and Stewart, A.M., J. Phys. F, 18, L223, 1988; Hill, R.W. and Gschneidner, K.A., Jr., J. Phys. F, 18, 2545, 1988; Skriver, H.L. and Mertig, I., Phys. Rev. B, 41, 6553, 1990. Collocott, S.J. and Stewart, A.M., J. Phys.: Condens. Matter, 4, 6743, 1992; Pecharsky, V.K., Gschneidner, K.A., Jr. and Fort, D., Phys. Rev. B, 47, 5063, 1993. a At 18.6 GPa. b At 11 GPa. c At 2.2 GPa. d Calculated value. e Estimated. f Heat capacity results have been reported, but the resultant γ and θ D values are unreliable because of the presence of impurities and/or there was no reliable procedure or model to correct for the magnetic contribution to the heat capacity. g Based on the values reported for the purer Sm sample (IV). h At 4.5 GPa. TABLE 11. Room Temperature Elastic Moduli and Mechanical Properties Rare earth metal Elastic moduli (GPa) Mechanical properties (MPa) Recryst. temp. (°C) Young’s (elastic) modulus Shear modulus Bulk modulus Poisson’s ratio Yield strength 0.2% offset Ultimate tensile strength Uniform elongation (%) Reduction in area (%) Sc 74.4 29.1 56.6 0.279 173a 255a 5.0a 8.0a 550 Y 63.5 25.6 41.2 0.243 42 129 34.0 — 550 αLa 36.6 14.3 27.9 0.280 126a 130 7.9a — 300 βCe — — — — 86 138 — 24.0 — γCe 33.6 13.5 21.5 0.24 28 117 22.0 30.0 325 αPr 37.3 14.8 28.8 0.281 73 147 15.4 67.0 400 αNd 41.4 16.3 31.8 0.281 71 164 25.0 72.0 400 αPm 46b 18b 33b 0.28b — — — — 400b αSm 49.7 19.5 37.8 0.274 68 156 17.0 29.5 440 Eu 18.2 7.9 8.3 0.152 — — — — 300 αGd 54.8 21.8 37.9 0.259 15 118 37.0 56.0 500 αTb 55.7 22.1 38.7 0.261 — — — — 500 αDy 61.4 24.7 40.5 0.247 43 139 30.0 30.0 550 Ho 64.8 26.3 40.2 0.231 — — — — 520 Er 69.9 28.3 44.4 0.237 60 136 11.5 11.9 520 Tm 74.0 30.5 44.5 0.213 — — — — 600 βYb 23.9 9.9 30.5 0.207 7 58 43.0 92.0 300 Lu 68.6 27.2 47.6 0.261 — — — — 600 Note: For additional information, see Scott, T., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Gschneidner, K.A., Jr. and Eyring, L., Eds., North- Holland Physics, Amsterdam, 1978, 591. a Value is questionable. b Estimated. Physical Properties of the Rare Earth Metals 4-123 Section4.indb 123 5/2/05 9:24:56 AM TABLE 12. Liquid Metal Properties Near the Melting Point Rare earth metal Density (g/cm3) Surface tension (N/m) Viscosity (centipoise) Heat capacity (J/mol K) Thermal conductivity (W/cm K) Magnetic susceptibility χ × 104 (emu/mol) Electrical resistivity (µΩ·cm) ∆V (l→s)a (%) Spectral emittance at λ = 645 nm ε (%) Temp. Sc 2.80 0.954 — 44.2b — — — — — — Y 4.24 0.871 — 43.1 — — — — 36.8 1522–1647 La 5.96 0.718 2.65 34.3 0.238 1.20 133 –0.6 25.4 920–1287 Ce 6.68 0.706 3.20 37.7 0.210 9.37 130 +1.1 32.2 877–1547 Pr 6.59 0.707 2.85 43.0 0.251 17.3 139 –0.02 28.4 931–1537 Nd 6.72 0.687 — 48.8 0.195 18.7 151 –0.9 39.4 1021–1567 Pm 6.9b 0.680b — 50b — — 160b — — — Sm 7.16 0.431 — 50.2b — 18.3 182 –3.6 43.7 1075 Eu 4.87 0.264 — 38.1 — 97 242 –4.8 — — Gd 7.4 0.664 — 37.2 0.149 67 195 –2.0 34.2 1313–1600 Tb 7.65 0.669 — 46.5 — 82 193 –3.1 — — Dy 8.2 0.648 — 49.9 0.187 95 210 –4.5 29.7 1412–1437 Ho 8.34 0.650 — 43.9 — 88 221 –7.4 — — Er 8.6 0.637 — 38.7 — 69 226 –9.0 37.2 1529–1587 Tm 9.0b — — 41.4 — 41 235b –6.9 — — Yb 6.21 0.320 2.67 36.8 — — 113 –5.1 — — Lu 9.3 0.940 — 47.9b — — 224 –3.6 — — Note: For additional information, see Van Zytveld, J., in Handbook on the Physics and Chemistry of Rare Earths, Vol. 12, Gschneidner, K.A., Jr. and Eyring, L., Eds., North- Holland Physics, Amsterdam, 1989, 357. Stretz, L.A. and Bautista, R.G., in Temperature, Its Measurement and Control in Science and Industry, Vol. 4, part I, H.H. Plumb, Ed., Instrument Society of America, Pittsburgh, 1972, 489. King, T.S., Baria, D.N., and Bautista, R.G., Met. Trans. B, 7, 411, 1976; Baria, D.N., King, T.S., and Bautista, R.G., Met. Trans. B, 7, 577, 1976. a Volume change on freezing. b Estimated. TABLE 13. Ionization Potentials (Electronvolts) Rare earth I Neutral atom II Singly ionized III Doubly ionized IV Triply ionized V Quadruply ionized Sc 6.56144 12.79967 24.75666 73.4894 91.65 Y 6.217 12.24 20.52 60.597 77.0 La 5.5770 11.060 19.1773 49.95 61.6 Ce 5.5387 10.85 20.198 36.758 65.55 Pr 5.464 10.55 21.624 38.98 57.53 Nd 5.5250 10.73 22.1 40.41 — Pm 5.554 10.90 22.3 41.1 — Sm 5.6437 11.07 23.4 41.4 — Eu 5.6704 11.241 24.92 42.7 — Gd 6.1500 12.09 20.63 44.0 — Tb 5.8639 11.52 21.91 39.79 — Dy 5.9389 11.67 22.8 41.47