Ytterbium is a lustrous silver metal, and very malleable. In it’s beta form, it is semiconductive at pressures above 16,000 atmospheres. Ytterbium is of the rare earth family of elements and is reported to be the easiest of the rare earths to be rolled into thin sheets; ytterbium foils are used to measure pressure and as stress transducers. One of ytterbium’s isotopes (¹⁷⁰Yb) is used as a portable x-ray source. Ytterbium is also used in lasers, phosphors, ceramic capacitors, ferrite devices, catalysts and as a dopant for garnets.

Crystal Structure:   

     α phase, close-packed hexagonal, P6₃/mmc D^h₄; a=0.38799nm, c=0.63859nm at 24^oC.

     β phase, face-centered cubic, Fm3m O^h₅; a=0.54848 nm at 24 ^oC

     γ phase, body-centered cubic, Im3m O^h₉, a=0.444 nm at 763 ^oC

Atomic Weight: 173.04

Density:  

     α phase, 6.903 g/cm³ at 23 ^oC

     β phase, 6.966 g/cm³ at 24 ^oC

     γ phase, 6.57 g/cm³ at 763 ^oC

Melting Point: 824 ^oC

Boiling Point: 1196 ^oC

Phase Transformation Temperature:    

     α to β phase: A_s = 280 K

     β to α phase: M_s ≅ 260 K

     β to γ phase: 795 ^oC

Coefficient of Thermal Expansion (24 ^oC):  

     Linear: 26.3 μm/m ⋅ K

     Linear along crystal axes: 26.3 μm/m ⋅ K along a axis

     Volumetric: 78.9 x 10^-6 per K

Recrystallization Temperature: Approximately 300 ^oC

Thermal Conductivity: 38.5 W/m ⋅ K at 25 ^oC

 Vapor Pressure:  

     301 ^oC: 0.001 Pa

     400 ^oC: 0.101 Pa

     776 ^oC:  1013 Pa

Electrical Resistivity: 250 nΩ ⋅ m at 25 ^oC; 10 nΩ ⋅ m at 4 K

Temperature of Superconductivity: Bulk ytterbium is not superconducting down to 0.015 K at atmospheric pressure.

Magnetic Susceptibility: Volume: 3.4 x 10^-6 mks at 17 ^oC

Thermal Neutron Cross Section: 37 b

General Corrosion Behavior: Ytterbium tarnishes slightly in moist air. It oxidizes slowly at elevated temperatures and reacts readily with hydrogen at 250 ^oC.

Resistance to Specific Corroding Agents: Ytterbium does not react with cold water, but it will tarnish in hot water. It reacts vigorously with dilute acids.

Tensile Properties (Room Temperature):

              Tensile               Yield                                            Reduction

             Strength           Strength           Elongation              in Area

                 MPa                 MPa                      %                          %

                  58                    7                         43                          92

Hardness: 17 HV

Poisson’s Ratio: 0.207

Strain-Hardening Exponent: 0.62

Elastic Modulus (27 ^oC):  

      Tension: 23.9 GPa

       Shear:   9.9 GPa

         Bulk: 30.5 GPa

Kinematic Liquid Viscosity: 0.430 mm²/s at 824 ^oC

Liquid Surface Tension: 0.320 N/m at 820 ^oC