Ytterbium

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Ytterbium is a lustrous silver metal, and very malleable.  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, is formed by neutron irradiation of thullium. It is used as a portable radiograh source and foils are used to measure pressure and stress transducers. In it’s beta form, it is semiconductive at pressures above 16,000 atmospheres. 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.

General Characteristics:

Atomic Weight: 173.04

Hardness: 17 HV

Poisson’s Ratio: 0.207

Strain-Hardening Exponent: 0.62

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

Crystal Structure:

α phase: close-packed hexagonal, P63/mmc Dh4; a=0.38799nm, c=0.63859nm at 24oC.

β phase: face-centered cubic, Fm3m Oh5; a=0.54848 nm at 24 oC

γ phase: body-centered cubic, Im3m Oh9, a=0.444 nm at 763 oC

Thermal Properties:

Melting Point: 824 oC

Boiling Point: 1196 oC

Phase Transformation Temperature:

α to β phase: As = 280 K

β to α phase: Ms ≅ 260 K

β to γ phase: 795 oC

Coefficient of Thermal Expansion (24oC):

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 Properties:

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

Corrosion Properties:

General 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.

Chemical Properties:

Ytterbium does not react with cold waer but will tarnishes in hot water and slightly in moist air. It oxidizes slowly at elevated temperatures and reacts readily with hydrogen at 250o C.

Mechancial Properties:

Tensile Properties (Room Temperature):

Tensile strength: 58 MPa

Yield strength: 7 MPa

Elongation: 43%

Reduction in area: 92%

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