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Gadolinium

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Gadolinium



 
 
Gadolinium is a chemical element
Chemical element

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....
 that has the symbol Gd and atomic number
Atomic number

In chemistry and physics, the atomic number is the number of protons found in the atomic nucleus of an atom. It is conventionally represented by the symbol Z....
 64.

Characteristics
Gadolinium is a silvery-white, malleable and ductile rare-earth
Rare earth element

According to IUPAC, rare earth elements or rare earth metals are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium, and the fifteen lanthanoids....
 metal with a metallic lustre. It crystallizes in hexagon
Hexagon

In geometry, a hexagon is a polygon with six edges and six Vertex . A regular hexagon has Schl?fli symbol ....
al, close-packed alpha form at room temperature, but, when heated to 1508 K
Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
 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.






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Gadolinium is a chemical element
Chemical element

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....
 that has the symbol Gd and atomic number
Atomic number

In chemistry and physics, the atomic number is the number of protons found in the atomic nucleus of an atom. It is conventionally represented by the symbol Z....
 64.

Characteristics


Gadolinium
Gadolinium is a silvery-white, malleable and ductile rare-earth
Rare earth element

According to IUPAC, rare earth elements or rare earth metals are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium, and the fifteen lanthanoids....
 metal with a metallic lustre. It crystallizes in hexagon
Hexagon

In geometry, a hexagon is a polygon with six edges and six Vertex . A regular hexagon has Schl?fli symbol ....
al, close-packed alpha form at room temperature, but, when heated to 1508 K
Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
 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, forming a loosely-adhering oxide
Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
 which spall
Spall

Spall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure ....
s off, exposing more surface to oxidation. Gadolinium reacts slowly with water, and is soluble in dilute acids.

Gadolinium-157 has the highest thermal neutron capture
Neutron capture

Neutron capture is a kind of nuclear reaction in which an atomic nucleus collides with one or more neutrons and they merge to form a heavier nucleus....
 cross-section of any known nuclide with the exception of xenon-135
Xenon-135

135Xe is an unstable isotope of xenon with a half-lifeabout 9.2 hours. 135Xe is a fission product of Uranium which is the most powerful known neutron-absorbing...
, 49,000 barns
Barn (unit)

A barn is a unit of area. While the barn is not an SI unit, it is accepted for use with the SI. Originally used in nuclear physics for expressing the cross section area of nuclei and nuclear reactions, today it is used in all fields of particle physics to express the cross sections of any scattering process....
, but it also has a fast burn-out rate, limiting its usefulness as a nuclear control rod
Control rod

A control rod is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves. They are used in nuclear reactors to control the rate of fission of uranium and plutonium....
 material.

Gadolinium is strongly paramagnetic at room temperature, and exhibits ferromagnetic properties below room temperature.

Gadolinium demonstrates a magnetocaloric effect
Magnetic refrigeration

Magnetic refrigeration is a cooling technology based on the magnetocaloric effect. This technique can be used to attain extremely low temperatures , as well as the ranges used in common refrigerators, depending on the design of the system....
 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
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
 Gd5(Si
Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
2Ge
Germanium

Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, greyish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon....
2) .

Applications

Gadolinium is used for making gadolinium yttrium garnet
Gadolinium yttrium garnet

Gadolinium Yttrium Garnet is a variation of Nd:YAG with microwave and laser applications....
s, which have microwave
Microwave

Microwaves are electromagnetic radiation with wavelengths ranging from 1 mm to 1 m, or frequency between 0.3 hertz and 300 GHz....
 applications, and gadolinium compounds are used for making phosphor
Phosphor

A phosphor is a substance that exhibits the optical phenomenon of phosphorescence .Phosphors are transition metal compounds or rare earth element compounds of various types....
s for colour TV
Television

Television is a widely used telecommunication mass-media for transmitting and receiving moving , either monochrome or color, usually accompanied by sound....
 tubes. Gadolinium is also used for manufacturing compact disc
Compact Disc

A Compact Disc is an optical disc used to store Data , originally developed for storing digital audio. The CD, available on the market since October 1982, remains the standard physical medium for sale of commercial Sound recording and reproduction to the present day....
s and computer memory
Computer memory

Computer memory is usually meant to refer to the semiconductor technology that is used to store information in Electronics devices. Current primary computer memory makes use of integrated circuits consisting of silicon-based transistors....
.

Gadolinium is used in nuclear marine propulsion
Nuclear marine propulsion

Nuclear marine propulsion is propulsion of a ship powered by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships ....
 systems as a burnable poison. Gadolinium is also used as a secondary, emergency shut-down measure in some nuclear reactors, particularly of the CANDU
CANDU reactor

The CANDU reactor is a Canadian-invented, pressurized heavy water reactor developed initially in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited , the Hydro-Electric Power Commission of Ontario , Canadian General Electric , as well as several private industry participants....
 type.

Gadolinium also possesses unusual metallurgic
Metallurgy

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic Chemical element, their intermetallics, and their mixtures, which are called alloys....
 properties, with as little as 1% of gadolinium improving the workability and resistance of iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
, chromium
Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
, and related alloy
Alloy

An alloy is a partial or complete solid solution of one or more chemical element in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history....
s to high temperatures and oxidation.

Because of their paramagnetic
Paramagnetism

Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than 1 ....
 properties, solutions of organic
Organic chemistry

Organic chemistry is a discipline within chemistry which involves the science study of the structure, properties, composition, chemical reaction, and preparation of chemical compounds that contain carbon....
 gadolinium complex
Complex (chemistry)

In chemistry, a complex, also called a "coordination compound" or "metal complex", is a structure consisting of a central atom or molecule connected to surrounding atoms or molecules....
es and gadolinium compounds are used as intravenous MRI contrast agent
MRI contrast agent

MRI contrast agents are a group of contrast media used to improve the visibility of internal body structures in Magnetic resonance imaging . The most commonly used compounds for contrast enhancement are gadolinium-based....
 to enhance images in medical magnetic resonance imaging
Magnetic resonance imaging

GaneshMagnetic resonance imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body....
. Magnevist is the most widespread example.

Besides MRI, gadolinium (Gd) is also used in other imaging. In X-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
, gadolinium is contained in the phosphor layer, suspending in a polymer matrix at the detector. Terbium
Terbium

Terbium is a chemical element with the symbol Tb and atomic number 65....
-doped gadolinium oxysulfide
Gadolinium oxysulfide

Gadolinium oxysulfide , also called gadolinium sulfoxylate or GOS, is an inorganic compound, a mixed oxide-sulfide of gadolinium. Its CAS number is ....
 (Gd2O2S: Tb) at the phosphor layer is to convert the X-rays releasing from the source into light. Gd can emit at 540nm (green light spectrum
Spectrum

A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a Continuum . The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a triangular prism ; it has since been applied by analogy to many fields other than op...
 = 520 – 570nm), which is very useful for enhancing the imaging quality of the X-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
 that is exposed to the photographic film. Beside Gd's spectrum range, the compound also has a K-edge
K-edge

K-edge describes a sudden increase in the attenuation coefficient of photons occurring at a photon energy just above the binding energy of the K shell electron of the atoms interacting with the photons....
 at 50 kiloelectronVolts (keV), which means its absorption of X-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
 through photoelectric interactions is great. The energy conversion of Gd is up to 20%, which means, one-fifth of the X-ray striking on the phosphor layer can be converted into light photons.

Gadolinium oxyorthosilicate (Gd2SiO5, GSO; usually doped by 0.1-1% of Ce
Cerium

Cerium is a chemical element with the symbol Ce and atomic number 58....
) is a single crystal that is used as a scintillator
Scintillator

A scintillator is a material which exhibits the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, i.e....
 in medical imaging such as Positron Emission Tomography
Positron emission tomography

Positron emission tomography is a nuclear medicine medical imaging technique which produces a three-dimensional image or picture of functional processes in the body....
 (PET) or for detecting neutrons.

Gadolinium gallium garnet
Gadolinium gallium garnet

Gadolinium Gallium Garnet is a synthetic crystalline material of the garnet group, with good mechanical, thermal, and optical properties. It is typically colorless....
 (Gd3Ga5O12) is a material with good optical properties, and is used in fabrication of various optical components and as substrate material for magneto–optical films.

In the future, gadolinium ethyl sulfate, which has extremely low noise characteristics, may be used in maser
Maser

A maser is a device that produces coherence electromagnetic waves through amplification due to stimulated emission. Historically the term came from the acronym "Microwave Amplification by Stimulated Emission of Radiation", although modern masers emit over a broad portion of the electromagnetic spectrum....
s. Furthermore, gadolinium's high magnetic moment and low Curie temperature (which lies just at room temperature) suggest applications as a magnetic component for sensing hot and cold.

Due to extremely high neutron cross-section of gadolinium, this element is very effective for use with neutron radiography.

History

In 1880, Swiss
Switzerland

Switzerland is a landlocked Swiss Alps country of roughly 7.7 million people in Western Europe with an area of 41,285 km?. Switzerland is a federal republic consisting of 26 states called Cantons of Switzerland....
 chemist
Chemist

A chemist is a scientist trained in the science of chemistry. Chemists study the composition of matter and its properties such as density, acidity, size and shape....
 Jean Charles Galissard de Marignac
Jean Charles Galissard de Marignac

Jean Charles Galissard de Marignac was a Switzerland chemistry whose work with atomic weights suggested the possibility of isotopes and the packing fraction of cell nucleus and whose study of the rare earth elements led to his discovery of ytterbium in 1878 and codiscovery of gadolinium in 1880....
 observed spectroscopic lines due to gadolinium in samples of didymium
Didymium

Didymium is a mixture of the elements praseodymium and neodymium. It is used in eye protection for glassblowing and blacksmithing, especially when a gas powered forge is used, where it provides a filter which blocks the yellowish light emitted by the hot sodium in the glass, without having a detrimental effect on general vision, unlike dar...
 and gadolinite
Gadolinite

Gadolinite is a mineral of a nearly black color and vitreous Lustre , and consisting principally of the Silicate minerals of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2ironberyllium2silicon2oxygen10....
; French
France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
 chemist Paul Émile Lecoq de Boisbaudran
Paul Emile Lecoq de Boisbaudran

Paul ?mile Lecoq de Boisbaudran was a French chemist born in Cognac. In 1858 he joined the family winemaking business, but a year later was working as a chemist....
 separated gadolinia
Gadolinium(III) oxide

Gadolinium oxide is a chemical compound. It has the B-M2O3 structure similar to the lanthanide sesquioxides, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3....
, the oxide
Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
 of Gadolinium, from Mosander's yttria in 1886. The element itself was isolated only recently.

Gadolinium, like the mineral gadolinite
Gadolinite

Gadolinite is a mineral of a nearly black color and vitreous Lustre , and consisting principally of the Silicate minerals of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2ironberyllium2silicon2oxygen10....
, is named after Finnish
Finland

Finland , officially the Republic of Finland , is a Nordic countries situated in the Fennoscandian region of northern Europe. It borders Sweden on the west, Russia on the east, and Norway on the north, while Estonia lies to its south across the Gulf of Finland....
 chemist and geologist
Geologist

For other uses, see Geologist .A geologist is a contributor to the science of geology, studying the physical structure and processes of the Earth and planets of the solar system ....
 Johan Gadolin
Johan Gadolin

Johan Gadolin was a Finnish people chemist, physicist and mineralogist. Gadolin discovered the chemical element yttrium. He was also the founder of Finnish chemistry research, as the second holder of the Chair of Chemistry, established in 1761 and first held by Pehr Adrian Gadd ....
.

In older literature, the natural form of the element is often called an earth, meaning that the element came from Earth. In fact, gadolinium is the element that comes from the earth, gadolinia. Earths are compounds of the element and one or more other elements. The two most common combining-elements are oxygen and sulfur. For example, gadolinia contains gadolinium oxide (Gd2O3).

Biological role

Gadolinium has no known native biological role, but in research on biological systems it has a few roles. It is used as a component of MRI contrast agent
MRI contrast agent

MRI contrast agents are a group of contrast media used to improve the visibility of internal body structures in Magnetic resonance imaging . The most commonly used compounds for contrast enhancement are gadolinium-based....
s, as, in the 3+ oxidation state, the metal has 7 unpaired f electrons. This causes water around the contrast agent to relax
Relaxation (NMR)

In Nuclear magnetic resonance spectroscopy and Magnetic resonance imaging the term relaxation describes several processes by which nuclear magnetization prepared in a non-equilibrium state return to the equilibrium distribution....
 quickly, enhancing the quality of the MRI scan. Second, as a member of the lanthanides, it is used in various ion channel
Ion channel

Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of all living cell s by allowing the flow of ions down their electrochemical gradient....
 electrophysiology experiments, where it is used to block sodium leak channels, as well as to stretch activated ion channels.

Gadolinium-based contrast agents are dangerous in patients with kidney disease. The contrast agent is normally chelated as it is expected to pass through the body quickly. In patients with kidney disease, the excretion is slower and the gadolinium becomes unbound, causing serious health issues.

Occurrence

Gadolinium is never found in nature as the free element, but is contained in many rare minerals such as monazite
Monazite

Monazite is a reddish-brown phosphate mineral containing Rare earth element metals and is an important source of thorium, lanthanum, and cerium....
 and bastnäsite. It occurs only in trace amounts in the mineral gadolinite
Gadolinite

Gadolinite is a mineral of a nearly black color and vitreous Lustre , and consisting principally of the Silicate minerals of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2ironberyllium2silicon2oxygen10....
, which was also named after Johan Gadolin
Johan Gadolin

Johan Gadolin was a Finnish people chemist, physicist and mineralogist. Gadolin discovered the chemical element yttrium. He was also the founder of Finnish chemistry research, as the second holder of the Chair of Chemistry, established in 1761 and first held by Pehr Adrian Gadd ....
. Today, it is prepared by ion exchange
Ion exchange

Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex . In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic 'ion exchangers'....
 and solvent extraction techniques, or by the reduction of its anhydrous fluoride with metallic calcium
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
.

Value


In 1994, the cost of gadolinium was about US$
United States dollar

The United States dollar is the unit of currency of the United States and was defined by the Coinage Act of 1792 to be between 371 and 416 grains of silver ....
 0.12 per gram
Gram

The gram , ; symbol g, is a Physical unit of mass.Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre, and at the temperature of melting ice" , a gram is now defined as one one-thousandth of the SI base unit, the kilogram, or Scientific notation kg, which itself is...
, and it has only increased in value by about US$ 0.01 per gram since then.: 1994.....$0.121 per gram ( or $55 per pound
Pound (mass)

The pound or pound-mass is a Units of measurement of massused in the Imperial unit, United States customary units and other systems of measurement....
) 1995.....$0.121 per gram ( or $55 per pound
Pound (mass)

The pound or pound-mass is a Units of measurement of massused in the Imperial unit, United States customary units and other systems of measurement....
) 1996.....$0.115 per gram (or $115 per kilogram
Kilogram

The kilogram or kilogrammeThe spelling kilogram is used by the International Committee for Weights and Measures and the U.S....
) 1997.....$0.115 per gram (or $115 per kilogram) 1998.....$0.115 per gram (or $115 per kilogram) 1999.....$0.115 per gram (or $115 per kilogram) 2000.....$0.130 per gram (or $130 per kilogram) 2001.....$0.130 per gram (or $130 per kilogram) 2002.....$0.130 per gram (or $130 per kilogram) 2003.....$0.130 per gram (or $130 per kilogram) 2004.....$0.130 per gram (or $130 per kilogram) 2005.....$0.130 per gram (or $130 per kilogram)

Compounds

Compounds of gadolinium include:

  • Fluoride
    Fluoride

    Fluoride is the Redox form of fluorine. Both organic compounds and inorganic compounds containing the chemical element fluorine are considered fluorides....
    s: GdF3
  • Chloride
    Chloride

    The chloride ion is formed when the chemical element chlorine picks up one electron to form an anion Cl−....
    s: GdCl3
    Gadolinium(III) chloride

    Gadolinium chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid....
  • Bromide
    Bromide

    A bromide ion is a bromine atom with electric charge of -1.Compounds with bromine in formal oxidation state -1 are called bromides, and each individual chemical in this class can be called a bromide, as well....
    s: GdBr3
  • Nitrate
    Nitrate

    In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms . In organic chemistry the esters of nitric acid and various alcohols are called nitrates....
    s: Gd(NO3)3
    Gadolinium nitrate

    Gadolinium nitrate is an inorganic compound of gadolinium. It is used as a water-soluble neutron poison in nuclear reactors....
  • Iodide
    Iodide

    An iodide ion is an iodine with a −1 electric charge. Compounds with iodine in formal oxidation state −1 are called iodides. This can include ionic compounds such as caesium iodide or covalent compounds such as phosphorus triiodide....
    s: GdI3
  • Oxide
    Oxide

    An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
    s: Gd2O3
    Gadolinium(III) oxide

    Gadolinium oxide is a chemical compound. It has the B-M2O3 structure similar to the lanthanide sesquioxides, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3....
  • Sulfide
    Sulfide

    The term sulfide refers to several types of chemical compounds containing sulfur in its lowest oxidation number of −2.Formally, "sulfide" is the dianion, S2−, which exists in strongly alkaline aqueous solutions formed from H2S or alkali metal salts such as Li2S, Na2S, and K2...
    s: Gd2S3
  • Nitride
    Nitride

    In chemistry a nitride is a compound of nitrogen with a less electronegative element where nitrogen has an oxidation state of -3. Note that there are exceptions to this naming convention, the nitrides of hydrogen, NH3 and carbon, 2, are called ammonia and cyanogen respectively and that the nitrides of chlorine, bromine,...
    s: GdN
  • Organics
    Organic compound

    An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
    : gadodiamide
    Gadodiamide

    Gadodiamide is a gadolinium based contrast agent used in magnetic resonance imaging procedures to assist in the visualization of blood vessels. It is commonly marketed under the trade name Omniscan....


See also gadolinium compounds.

Isotopes


Naturally occurring gadolinium is composed of 6 stable isotope
Isotope

Isotopes are any of the different types of atoms of the same chemical element, each having a different atomic mass . Isotopes of an element have atomic nucleus with the same number of protons but different numbers of neutron....
s, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd and 160Gd, and 1 radioisotope, 152Gd, with 158Gd being the most abundant (24.84% natural abundance
Natural abundance

In chemistry, natural abundance refers to the abundance isotopes of a chemical element as naturally found on a planet. The relative atomic mass of these isotopes is the atomic weight listed for the element in the periodic table....
). The predicted double beta decay of 160Gd has never been observed (only lower limit on its half-life
Half-life

The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations....
 of more than 1.3×1021 years has been set experimentally ).

Twenty nine radioisotopes have been characterized, with the most stable being alpha-decaying 152Gd (naturally occurring) with a half-life of 1.08×1014 years, and 150Gd with a half-life of 1.79×106 years. All of the remaining radioactive isotopes have half-lives less than 74.7 years. The majority of these have half-lives less than 24.6 seconds. Gadolinium isotopes have 4 metastable isomer
Nuclear isomer

A nuclear isomer is a metastable state of an atomic nucleus caused by the excited state of one or more of its nucleons. A nuclear isomer occupies a higher energy state than the corresponding non-excited nucleus, called the ground state....
s, with the most stable being 143mGd (T½=110 seconds), 145mGd (T½=85 seconds) and 141mGd (T½=24.5 seconds).

The primary decay mode at atomic mass
Atomic mass

The atomic mass is the mass of an atom, most often expressed in Atomic mass units. The atomic mass may be considered to be the total mass of protons, neutrons and electrons in a single atom ....
es lower than the most abundant stable isotope, 158Gd, is electron capture
Electron capture

Electron capture is a decay mode for isotopes that will occur when there are too many protons in the atomic nucleus of an atom and insufficient energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron emission....
, and the primary mode at higher atomic masses is beta decay
Beta decay

In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted. In the case of electron emission, it is referred to as beta minus , while in the case of a positron emission as beta plus ....
. The primary decay product
Decay product

In nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a nuclide resulting from the radioactive decay of a parent isotope or precursor nuclide....
s for isotopes of weights lower than 158Gd are the element Eu (europium
Europium

Europium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent Europe.Characteristics ...
) isotopes and the primary products at higher weights are the element Tb (terbium
Terbium

Terbium is a chemical element with the symbol Tb and atomic number 65....
) isotopes.

Gadolinium-153 has a half-life of 240.4±10 days and emits gamma radiation with strong peaks at 41 keV and 102 keV. It is used as a gamma ray source in X-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
 absorptiometry or bone density gauges for osteoporosis
Osteoporosis

Osteoporosis is a disease of bone that leads to an increased risk of bone fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is disrupted, and the amount and variety of collagen proteins in bone is altered....
 screening, and in the Lixiscope portable X-ray imaging system.

Precautions

As with the other lanthanides, gadolinium compounds are of low to moderate toxicity
Toxicity

Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver ....
, although their toxicity has not been investigated in detail. Also, in patients with renal failure or other pro-inflammatory conditions, there is data associating its use with development of nephrogenic fibrosing dermopathy as a side effect of gadolinium chelates used as a contrast agent for MRI examinations.

General references



External links