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About the Rota Period
Rota Period Explained (pdf)
Rota Period Abstract Published in JSE (pdf)
Atomic Radius, Electronegativity, Electropositivity, First Ionization Energy, Mass + Z, Metallic Properties and Oxidation State Trends
*** Iron (Fe) is an example of how multi valence elements are displayed.
Hf - Hafnium
- Atomic Number: 72
- Atomic Weight (Mass): 178.49000
- Melting Point: 3410 °C
- Boiling Point: 5660 °C
- Orbital Class: 5d
- Orbital: [Xe] 4f14 5d2 6s2
- Class: Transition Metals
- Electronegativity: 1.3
- Density: 13.07 g.cm-3
- Van der Waals Radius: 200.pm
- Ionic Radius: 0.075 nm (+4)
- First Ionization Energy: 658.52 kJ mol-1
- Second Ionization Energy: 1437.64 kJ mol-1
- Third Ionization Energy: 2248.12 kJ mol-1
- Heat of Fusion: 25.5 kJ mol-1
- Heat of Vaporization: 570.7 kJ mol-1
- Heat of Atomization: 618.9 kJ mol-1
- Electrical Conductivity: 33.08 µ Ωcm
- Thermal Conductivity: 23 W m-1 K-1
- Related To: C, Si, Ti, Ge, Zr, Pd, Sn, Ce, Pr, Tb, Hf, Pt, Pb, Th, Bk, Rf,
Hafnium is one of the Group IV transition elements that is refined from various zirconic mineral deposits. It's primary uses are due to its ability as a nuclear "getter" or absorber of neutrons. It is a primary component in nuclear control rods for this purpose. It also finds uses as a dopant in the alloy of steel and titanium. It is also used in the production of mantles for high intensity incandescent lamps.
Hafnium is replacing polysilicon as the principle gate or electrode material in metal oxide semiconductor field effect transistors (MOSFETs) which are the basis for all modern semiconductors. As semiconductors have gotten smaller, the limiting factor in further size reduction has been the ability of the silicon oxide gate to perform below 10 angstroms where leakage occurs. Recent research has been devoted to the development of High-k materials which can function as a di-electric barrier or gate with lower leakage. Using hafnium based alloys as this di-electric gate has allowed for the development of MOSFET gates smaller than 10 angstroms. This allows for further size reduction, reduced switching power requirements and improved performance.
Hafnium is a Block D, Group 4, Period 6 element. The electronic configuration is [Xe] 4f14 5d2 6s2. In its elemental form hafnium's CAS number is 7440-58-6. The hafnium atom has a radius of 156.4.pm and it's Van der Waals radius is 200.pm.
Hafnium was first discovered by Dirk Coster in 1923.
French: hafnium, German: Hafnium, Italian: afnio, Portuguese: Hafnio, Spanish: hafnio, Swedish: Hafnium
This element can be purchased in a variety of forms including as metal, compounds, ultra high purity, nanoparticles, and isotopes at www.americanelements.com
Reproduced With Permission: www.americanelements.com
Click Here For More Information About Hafnium: Wikipedia.org