Gadolinium is a chemical element that has the symbol Gd and atomic number 64.
Gadolinium is a silvery-white, malleable and ductile rare-earth metal with a metallic luster. It crystallizes in hexagonal, close-packed alpha form at room temperature, but, when heated to 1508 K or more, it transforms into its beta form, which has a body-centered cubic structure.
Unlike other rare earth elements, gadolinium is relatively stable in dry air. However, it tarnishes quickly in moist air and forms a loosely-adhering oxide that spalls off, and then exposes more surface to oxidation. Gadolinium reacts slowly with water, and it is soluble in dilute acids.
Gadolinium-157 has the highest thermal neutron capture cross-section of any known nuclide with the exception of Xenon-135, 49,000 barns, but it also has a fast burn-out rate, limiting its usefulness as a nuclear control rod material.
Gadolinium becomes superconductive below a critical temperature of 1.083 K. It is strongly paramagnetic at room temperature, and exhibits ferromagnetic properties below room temperature.
Gadolinium demonstrates a magnetocaloric effect whereby its temperature increases when it enters a magnetic field and decreases when it leaves the magnetic field. The effect is considerably stronger for the gadolinium alloy Gd5(Si2Ge2).
| Technical Data | ||||||||
| Symbol | Gd | Density (20°C)/gcm-3 | 7.886 | |||||
| Atomic number | 64 | Melting point /°C | 1312 | |||||
| No. of naturally occurring isotopes | 7 | Boiling point /°C | -3000 | |||||
| Atomic weight | 157.25 (+/-3) | ΔHvap/kJmol-1 | 301 | |||||
| Outer electron configuration | 4f7d46s2 | ΔHf(monoatomic gas/kJmol-1 | 398 | |||||
| Metal radius(6-coordinate)/pm | 180.4 | ΔH(hydration Ln3+)/kJmol-1 | 3571 | |||||
| Ionic radius(6-coordinate)/pm III | 93.8 | Ionization energy/kJ mol-1 I | 595 | |||||
| Ionic radius(6-coordinate)/pm II | - | Ionization energy/kJmol-1 II | 1172 | |||||
| Electrical resistivity | Ionization energy/kJmol-1 III | 1999 | ||||||
| (25°C)/μohm cm | 134 | |||||||
| Evaporation Techniques | ||||||||
| Temperature (oC) @Vap. Pressure | Techniques | Remarks | ||||||
| 10-8 Torr | 10-6 Torr | 10-4 Torr | Electron Beam | Crucible | Coil | Boat | ||
| 760 | 900 | 1175 | Excellent | Al2O3 | - | Tantalum | High Tantalum solubility. Go to Evaporation Sources Page | |