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Encyclopedia > Hafnium
72 lutetiumhafniumtantalum
Zr

Hf

Rf
General
Name, Symbol, Number hafnium, Hf, 72
Chemical series transition metals
Group, Period, Block 4, 6, d
Appearance grey steel
Standard atomic weight 178.49(2) g·mol−1
Electron configuration [Xe] 4f14 5d2 6s2
Electrons per shell 2, 8, 18, 32, 10, 2
Physical properties
Phase solid
Density (near r.t.) 13.31 g·cm−3
Liquid density at m.p. 12 g·cm−3
Melting point 2506 K
(2233 °C, 4051 °F)
Boiling point 4876 K
(4603 °C, 8317 °F)
Heat of fusion 27.2 kJ·mol−1
Heat of vaporization 571 kJ·mol−1
Heat capacity (25 °C) 25.73 J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 2689 2954 3277 3679 4194 4876
Atomic properties
Crystal structure hexagonal
Oxidation states 4
(amphoteric oxide)
Electronegativity 1.3 (scale Pauling)
Ionization energies
(more)
1st: 658.5 kJ·mol−1
2nd: 1440 kJ·mol−1
3rd: 2250 kJ·mol−1
Atomic radius 155 pm
Atomic radius (calc.) 208 pm
Covalent radius 150 pm
Miscellaneous
Magnetic ordering no data
Electrical resistivity (20 °C) 331 n Ω·m
Thermal conductivity (300 K) 23.0 W·m−1·K−1
Thermal expansion (25 °C) 5.9 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 3010 m/s
Young's modulus 78 GPa
Shear modulus 30 GPa
Bulk modulus 110 GPa
Poisson ratio 0.37
Mohs hardness 5.5
Vickers hardness 1760 MPa
Brinell hardness 1700 MPa
CAS registry number 7440-58-6
Selected isotopes
Main article: Isotopes of hafnium
iso NA half-life DM DE (MeV) DP
172Hf syn 1.87 y ε 0.350 172Lu
174Hf 0.162% 2×1015 y α 2.495 170Yb
176Hf 5.206% Hf is stable with 104 neutrons
177Hf 18.606% Hf is stable with 105 neutrons
178Hf 27.297% Hf is stable with 106 neutrons
178m2Hf syn 31 y IT 2.446 178Hf
179Hf 13.629% Hf is stable with 107 neutrons
180Hf 35.1% Hf is stable with 108 neutrons
182Hf syn 9×106 y β 0.373 182Ta
References

Hafnium (IPA: /ˈhæfniəm/) is a chemical element in the periodic table that has the symbol Hf and atomic number 72. A lustrous, silvery gray tetravalent transition metal, hafnium resembles zirconium chemically and it is found in zirconium minerals. Hafnium is used in tungsten alloys in filaments and electrodes, and it also acts as a neutron absorber in control rods in nuclear power plants. General Name, Symbol, Number lutetium, Lu, 71 Chemical series lanthanides Group, Period, Block n/a, 6, d Appearance silvery white Standard atomic weight 174. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Standard atomic weight 180. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... General Name, Symbol, Number rutherfordium, Rf, 104 Chemical series transition metals Group, Period, Block 4, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (261) g/mol Electron configuration probably [Rn] 5f14 6d2 7s2 Electrons per shell 2, 8, 18, 32, 32, 10, 2 Phase presumably a... Original Image: media:Hf-TableImage-BIG.png File links The following pages link to this file: Hafnium User:Femto/elements e9 Categories: GFDL images ... This is a standard display of the periodic table of the elements. ... An extended periodic table was suggested by Glenn T. Seaborg in 1969. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... A table of chemical elements ordered by atomic number and color coded according to type of element. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a horizontal row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... A Group 4 element is an element in periodic table group 4 (IUPAC style) in the periodic table, which consists of: titanium (22) zirconium (40) hafnium (72) rutherfordium (104) All of these elements are classed in Group 4 because their valence shell holds four electrons. ... A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides. ... D Block is a rap group based in Yonkers, New York. ... Color is an important part of the visual arts. ... Image File history File linksMetadata Download high-resolution version (2592x1944, 919 KB) Hafnium turnings, >99. ... The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units. ... To help compare different orders of magnitude we list here masses between 60. ... Hydrogen = 1 List of Elements in Atomic Number Order. ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (eg, a crystal). ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Standard atomic weight 131. ... e- redirects here. ... [[Image:Valence shell 011 Sodiumup of one or more electron subshells, or sublevels, which have two or more orbitals with the same angular momentum quantum number l. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... For other uses, see Solid (disambiguation). ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... Room temperature describes a certain temperature within enclosed space that is uses for various purposes by human beings. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... Fahrenheit is a temperature scale named after the German-Dutch physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... Italic text This article is about the boiling point of liquids. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... Fahrenheit is a temperature scale named after the German-Dutch physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... Standard enthalpy change of fusion of period three. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In chemistry and physics, Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The oxidation number of an element in a molecule or complex is the charge that it would have if all the ligands (basically, atoms that donate electrons) were removed along with the electron pairs that were shared with the central atom[1]. It means that the oxidation number is the... In chemistry, an amphoteric substance is one that can react with either an acid or base (more generally, the word describes something made of, or acting like, two components). ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... The ionization energy (IE) of an atom or of a molecule is the energy required to strip it of an electron. ... These tables list the ionization energy in kJ/mol necessary to remove an electron from a neutral atom (first energy), respectively from a singly, doubly, etc. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... Atomic radius: Ionic radius Covalent radius Metallic radius van der Waals radius edit Atomic radius, and more generally the size of an atom, is not a precisely defined physical quantity, nor is it constant in all circumstances. ... You have big harry skanky balls ... One picometre is defined as 1x10-12 metres, in standard units. ... You have big harry skanky balls ... Atomic radius: Ionic radius Covalent radius Metallic radius van der Waals radius edit The covalent radius, rcov, is a measure of the size of atom which forms part of a covalent bond. ... You have big harry skanky balls ... Magnetic lines of force of a bar magnet shown by iron filings on paper In physics, magnetism is one of the phenomena by which materials exert attractive or repulsive forces on other materials. ... // Headline text POOP!! Danny Hornsby (also known as Gnome) is a measure indicating how strongly a Gnome can opposes the flow of electric current. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... Sound is a vibration that travels through an elastic medium as a wave. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... In solid mechanics, Youngs modulus (E) is a measure of the stiffness of a given material. ... In materials science, shear modulus, G, or sometimes S or μ, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain:[1] where = shear stress; force acts on area ; = shear strain; length changes by amount . ... The bulk modulus (K) of a substance essentially measures the substances resistance to uniform compression. ... Figure 1: Rectangular specimen subject to compression, with Poissons ratio circa 0. ... This article or section does not cite any references or sources. ... A Vickers hardness tester The Vickers hardness test was developed in the early 1920s as an alternative method to measure the hardness of materials. ... The Brinell scale characterises the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Hafnium (Hf) Standard atomic mass: 178. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... The decay energy is the energy released by a nuclear decay. ... The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... General Name, Symbol, Number lutetium, Lu, 71 Chemical series lanthanides Group, Period, Block n/a, 6, d Appearance silvery white Standard atomic weight 174. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Alpha decay is a form of radioactive decay in which an atomic nucleus ejects an alpha particle and transforms into a nucleus with mass number 4 less and atomic number 2 less. ... Yb redirects here; for the unit of information see Yottabit General Name, Symbol, Number ytterbium, Yb, 70 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 173. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not adequately cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not adequately cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not adequately cite its references or sources. ... A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... This article is about electromagnetic radiation. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not adequately cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not adequately cite its references or sources. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Standard atomic weight 180. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... The periodic table of the chemical elements A chemical element, or element for short, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... For a diagram of the periodic table, see standard periodic table below. ... It has been suggested that List of elements by atomic number be merged into this article or section. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... In chemistry, a tetravalence is the state of an atom with four electrons available for covalent chemical bonding in its valence (outermost electron shell). ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. ... General Name, Symbol, Number tungsten, W, 74 Chemical series transition metals Group, Period, Block 6, 6, d Appearance grayish white, lustrous Standard atomic weight 183. ... An alloy is a homogeneous mixture of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... HEROW!!! A filament of a 60-watt light bulb at 75X magnification An electrical filament is a thread of metal, usually tungsten, which is used to convert electricity into heat and light for the incandescent light bulb as made in 1878 by Joseph Wilson Swan, among others. ... An electrode is an electrical conductor used to make contact with a metallic part of a circuit (e. ... This article or section does not adequately cite its references or sources. ... A control rod is a rod made of a chemical element capable of absorbing many neutrons without decaying themselves. ... A nuclear power station. ...

Contents

Notable characteristics

Hafnium metal
Hafnium metal

Hafnium is a shiny silvery, ductile metal that is corrosion resistant and chemically extremely similar to zirconium. The physical properties of hafnium are markedly affected by zirconium impurities, and these two elements are among the most difficult ones to separate. A notable physical difference between them is their density (zirconium being about half as dense as hafnium), but chemically the elements are extremely similar. Hafnium metal. ... Hafnium metal. ... Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). ... It has been suggested that Properties and uses of metals be merged into this article or section. ... See corrosive for the hazard. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ...


The most notable physical property of hafnium is that it has a very high neutron-capture cross-section, and several isotopes of hafnium nuclei can absorb multiple neutrons. This makes hafnium a good material for use in the control rods for nuclear reactors. Its neutron-capture cross-section is about 600 times that of zirconium. (Other elements that are good neutron-absorbers for control rods are cadmium and boron.)


Separation of hafnium and zirconium becomes very important in the nuclear power industry, since zirconium is a good fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section, and a good chemical stability at high temperatures. However, because of hafnium's neutron-absorbing properties, hafnium impurities in zirconium would cause it to be far less useful for nuclear reactor materials applications. Thus a nearly-complete separation of zirconium and hafnium is necessary for their use in nuclear power.


Hafnium carbide is the most refractory binary compound known, with a melting point >3890 °C, and hafnium nitride is the most refractory of all known metal nitrides, with a melting point of 3310 °C.[1] This has led to proposals that hafnium or its carbides might be useful as construction materials that are subjected to very high temperatures. This article is in need of attention from a chemistry expert. ... In metallurgy, refraction is a property of metals that indicates their ability to withstand heat. ... A binary compound is a chemical compound consisting of only atoms of two different elements, e. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ...


The metal is resistant to concentrated alkalis, but halogens react with it to form hafnium tetrahalides.[1] At higher temperatures hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. In chemistry, an alkali (from Arabic: al-qalyالقلوي, القالي ) is a basic, ionic salt of an alkali metal or alkali earth metal element. ... The halogens or halogen elements are a series of nonmetal elements from Group 17 (old-style: VII or VIIA; Group 7 IUPAC Style) of the periodic table, comprising fluorine, F, chlorine, Cl, bromine, Br, iodine, I, and astatine, At. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Standard atomic weight 10. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark grey with bluish tinge Standard atomic weight 28. ...


The nuclear isomer Hf-178-m2 is also a source of cascades of gamma rays whose energies total to 2.45 MeV per decay.[2] It is notable because it has the highest excitation energy of any comparably long-lived isomer of any element. One gram of pure Hf-178-m2 would contain approximately 1330 megajoules of energy, the equivalent of exploding about 317 kilograms (700 pounds) of TNT. Possible applications requiring such highly concentrated energy storage are of interest. For example, it has been studied as a possible power source for gamma ray lasers.[3] A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... This article is about electromagnetic radiation. ... The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. ... R-phrases S-phrases Related Compounds Related compounds picric acid hexanitrobenzene Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Trinitrotoluene (TNT) is a chemical compound with the formula C6H2(NO2)3CH3. ... Experiment with a laser (US Military) In physics, a laser is a device that emits light through a specific mechanism for which the term laser is an acronym: Light Amplification by Stimulated Emission of Radiation. ...


Applications

Hafnium is used to make control rods for nuclear reactors because of its ability to absorb neutrons (its thermal neutron absorption cross section is nearly 600 times that of zirconium), excellent mechanical properties and exceptional corrosion-resistance properties. Core of a small nuclear reactor used for research. ... This article or section does not adequately cite its references or sources. ...


Other uses:

  • In gas-filled and incandescent lamps, for scavenging oxygen and nitrogen,
  • As the electrode in plasma cutting because of its ability to shed electrons into air,
  • and in iron, titanium, niobium, tantalum, and other metal alloys.
  • A hafnium-based compound is employed in high-k dielectric gate insulators in the 45nm generation of integrated circuits.[4] Intel and IBM through separate laboratory tests found that certain hafnium compounds (eg. hafnium oxide or hafnium silicate) can be used as more effective insulators than silicon dioxide, and they are planning to use the element to produce faster and more energy efficient chips - by allowing circuitry scaling to be reduced to less than 45 nanometers.[5][6]
  • DARPA has been intermittently funding programs in the US to determine the possibility of using a nuclear isomer of hafnium (the above mentioned Hf-178-m2) to construct small, high yield weapons with simple x-ray triggering mechanisms—an application of induced gamma emission. That work follows over two decades of basic research by an international community[7] into the means for releasing the stored energy upon demand. There is considerable opposition to this program, both because the idea may not work[8], and because uninvolved countries might perceive an imagined "isomer weapon gap" that would justify their further development and stockpiling of conventional nuclear weapons. A related proposal is to use the same isomer to power Unmanned Aerial Vehicles, [9] which could remain airborne for weeks at a time.

The incandescent light bulb uses a glowing wire filament heated to white-hot by electrical resistance, to generate light (a process known as thermal radiation). ... Plasma cutting is a process used to cut steel and other metals (or sometimes other materials) using a plasma torch. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... General Name, Symbol, Number niobium, Nb, 41 Chemical series transition metals Group, Period, Block 5, 5, d Appearance gray metallic Standard atomic weight 92. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Standard atomic weight 180. ... An alloy is a homogeneous mixture of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... The term high-κ dielectric refers to materials with a high dielectric constant (κ) (relative to silicon dioxide) which are going to be used [1] in next generation semiconductor components to replace the SiO2 gate dielectric, especially for the low standby power (LSTP) applications at the 45 nm technology node. ... Large power N-channel field effect transistor The field-effect transistor (FET) is a type of transistor that relies on an electric field to control the shape and hence the conductivity of a channel in a semiconductor material. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... The Defense Advanced Research Projects Agency (DARPA) is an agency of the United States Department of Defense responsible for the development of new technology for use by the military. ... A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... In physics, induced gamma emission (IGE) refers to the process of fluorescent emission of gamma rays from excited nuclei, or from nuclear isomers. ... Unmanned Aerial Vehicle over Iraq. ...

History

The 1869 periodic table by Mendeleev had implicitly predicted the existence of a heavier analog of titanium and zirconium, but in 1871 Mendeleev placed lanthanum in that spot. Image File history File links Download high-resolution version (605x606, 58 KB) Seal of the Faculty of Science of the University of Copenhagen This is a logo of an organization, item, or event, and is protected by copyright and/or trademark. ... Image File history File links Download high-resolution version (605x606, 58 KB) Seal of the Faculty of Science of the University of Copenhagen This is a logo of an organization, item, or event, and is protected by copyright and/or trademark. ... Buildings in the H. C. Ørsted Institute Niels Bohr Institute for Astronomy, Physics and Geophysics Institute for Mathematical Sciences August Krogh Institute The Faculty of Science (Det naturvidenskabelige fakultet in Danish) at the University of Copenhagen consists of both mathematical and natural sciences, and is divided into 11 institutes including... Portrait of Dimitri Mendeleyev by Ilya Repin Dmitri Mendeleev (Russian: , Dmitriy Ivanovich Mendeleyev  ) (8 February [O.S. 27 January] 1834 in Tobolsk – 2 February [O.S. 20 January] 1907 in Saint Petersburg), was a Russian chemist. ... Professor Dimitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties which appeared with some regularity as he laid out the elements from lightest to heaviest. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ...


The existence of a gap in the periodic table for an as-yet undiscovered element 72 was predicted by Henry Moseley in 1914. Hafnium was named for the Latin name Hafnia for "Copenhagen", the home town of Niels Bohr. It was discovered by Dirk Coster and Georg von Hevesy in 1923 in Copenhagen, Denmark, validating the original 1869 prediction of Mendeleev. Soon thereafter, the new element was predicted to be associated with zirconium by using the Bohr theories of the atom, and it was finally found in zircon through X-ray spectroscopy analysis in Norway. Henry Moseley at work. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Copenhagen (IPA: or ; Danish: IPA: ) is the capital of Denmark and the countrys largest city. ... Niels (Henrik David) Bohr (October 7, 1885 – November 18, 1962) was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in 1922. ... This article contains information that has not been verified. ... George de Hevesy (August 1, 1885 - July 5, 1966) was a Hungarian chemist who was important in the development of the tracer method where radioactive tracers are used to study chemical processes, e. ... Year 1923 (MCMXXIII) was a common year starting on Monday (link will display the full calendar) of the Gregorian calendar. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Extremely high resolution spectrogram of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of the interaction between radiation (electromagnetic radiation, or light, as well as particle radiation) and matter. ...


Hafnium was separated from zirconium through repeated recrystallization of the double ammonium or potassium fluorides by Jantzen and von Hevesey. Metallic hafnium was first prepared by Anton Eduard van Arkel and Jan Hendrik de Boer by passing hafnium tetra-iodide vapor over a heated tungsten filament. This process for differential purification of Zr and Hf is still in use today. A ball-and-stick model of the ammonium cation Fumes from hydrochloric acid and ammonia forming a white cloud of ammonium chloride Ammonium is also an old name for the Siwa Oasis in western Egypt. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Standard atomic weight 39. ... Anton Eduard van Arkel, (s-Gravenzande Netherlands, November 19, 1893 – Leiden, March 14, 1976) was a Dutch chemist. ... General Name, Symbol, Number tungsten, W, 74 Chemical series transition metals Group, Period, Block 6, 6, d Appearance grayish white, lustrous Standard atomic weight 183. ...


The Faculty of Science of the University of Copenhagen uses in its seal a stylized image of hafnium. Buildings in the H. C. Ørsted Institute Niels Bohr Institute for Astronomy, Physics and Geophysics Institute for Mathematical Sciences August Krogh Institute The Faculty of Science (Det naturvidenskabelige fakultet in Danish) at the University of Copenhagen consists of both mathematical and natural sciences, and is divided into 11 institutes including... The University of Copenhagen (Danish: Københavns Universitet) is the oldest and largest university and research institution in Copenhagen, Denmark. ... Seal on envelope A seal is an impression printed on, embossed upon, or affixed to a document (or any other object) in order to authenticate it, in lieu of or in addition to a signature. ...


Occurrence

Hafnium is estimated to make up about 0.00058% of the Earth's upper crust by weight. It is found combined in natural zirconium compounds but it does not exist as a free element in nature. Minerals that contain zirconium, such as alvite [(Hf, Th, Zr)SiO4 H2O], thortveitite, and zircon (ZrSiO4), usually contain between 1 and 5% hafnium. Hafnium and zirconium have nearly identical chemistry, which makes the two difficult to separate. About half of all hafnium metal manufactured is produced as a by-product of zirconium refinement. This is done through reducing hafnium(IV) chloride with magnesium or sodium in the Kroll process. This article is about Earth as a planet. ... Earth cutaway from core to exosphere. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance as coarse powder, dark grey with bluish tinge Standard atomic weight 28. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Thortveitite is a mineral consisting of scandium yttrium silicate and is the primary source of scandium. ... Zircon is a mineral belonging to the group of nesosilicates. ... Hafnium(IV) chloride Used for the preparation of metallic hafnium by the Kroll process. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Standard atomic weight 22. ... The Kroll process is a pyrometallurgical industrial process used to produce metallic titanium. ...

A lump of hafnium which has been oxidized on one side and is showing thin film optical effects.
A lump of hafnium which has been oxidized on one side and is showing thin film optical effects.

Image File history File linksMetadata Download high-resolution version (1824x1551, 434 KB) Upper side of a lump of highly pure hafnium used for evaporating as HfO2 onto glass along with silica to form multi layer dielectric optics. ... Image File history File linksMetadata Download high-resolution version (1824x1551, 434 KB) Upper side of a lump of highly pure hafnium used for evaporating as HfO2 onto glass along with silica to form multi layer dielectric optics. ... Thin-film optics is the branch of optics which deals with very thin structured layers of different materials. ...

Precautions

Care needs to be taken when machining hafnium because, like its sister metal zirconium, when hafnium is divided into fine particles, it is pyrophoric and can ignite spontaneously in air (see Dragon's Breath for a demonstration). Compounds that contain this metal are rarely encountered by most people. The pure metal is not considered toxic, but halfnium compounds should be handled as if they are toxic because the ionic forms of metals are normally at greatest risk for toxicity, and limited animal testing has been done for halfnium compounds. A pyrophoric substance is a substance that ignites spontaneously, that is, its autoignition temperature is below room temperature. ... It has been suggested that this article or section be merged into Shotgun shell. ...


See also

A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... In physics, induced gamma emission (IGE) refers to the process of fluorescent emission of gamma rays from excited nuclei, or from nuclear isomers. ...

References

  1. ^ a b Los Alamos National Laboratory - Hafnium
  2. ^ Lawrence Berkeley National Laboratory - Lund University, Nuclear data base
  3. ^ Laser Phys. Lett. 2, 162-167 (2005)
  4. ^ Intel Says Chips Will Run Faster, Using Less Power
  5. ^ Fulton, III, Scott M. (January 27, 2007). Intel Reinvents the Transistor. BetaNews. Retrieved on 2007-01-27.
  6. ^ Robertson, Jordan (January 27, 2007). Intel, IBM reveal transistor overhaul. AP. Retrieved on 2007-01-27.
  7. ^ Historical reference
  8. ^ Review of the underlying physics in 2004 Physics Today article
  9. ^ http://www.informationclearinghouse.info/article1534.htm
  • van Arkel, A.E., and de Boer, J.H., 1925, Preparation of pure titanium, zirconium, hafnium, and thorium metal: Zeitschrift für Anorganische und Allgemeine Chemie, v. 148, p. 345-350.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 27th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 27th day of the year in the Gregorian calendar. ...

External links

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  Results from FactBites:
 
Chemistry : Periodic Table : hafnium : key information (256 words)
Because hafnium has a good absorption cross section for thermal neutrons (almost 600 times that of zirconium), has excellent mechanical properties, and is extremely corrosion resistant, it is used for nuclear reactor control rods.
Hafnium carbide is the most refractory binary composition known, and the nitride is the most refractory metal nitride (m.p.
Hafnium extraction is always associated with its removal from zirconium as it is a contaminant of all zirconium minerals.
hafnium. The Columbia Encyclopedia, Sixth Edition. 2001-05 (287 words)
Hafnium is a lustrous, ductile, silvery metal with a hexagonal, close-packed crystalline structure.
Hafnium metal is produced by the Kroll process, in which a hafnium tetrahalide is reacted with magnesium or sodium metal.
Hafnium is found widely distributed in nature, usually in association with zirconium minerals such as zircon.
  More results at FactBites »

 
 

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