A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the
Terbium is a
chemical elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
with the symbol
Tb and
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
65. It is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s, including
ceriteCerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the Ce rich species and the La rich species...
,
gadoliniteGadolinite is a mineral of a nearly black color and vitreous luster, and consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2FeBe2Si2O10...
,
monaziteMonazite is a reddish-brown phosphate mineral containing rare earth metals and is an important source of thorium, lanthanum, and cerium. It occurs usually in small isolated crystals...
,
xenotimeXenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
and
euxeniteEuxenite or euxenite- is a brownish black mineral with a metallic luster. It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: 2O6. It occurs in granite pegmatites and detrital...
.
Terbium is used to
dopeA dopant, also called doping agent and dope, is an impurity element added to a crystal lattice in low concentrations in order to alter the optical/electrical properties of the crystal....
calcium fluorideCalcium fluoride is an insoluble ionic compound of calcium and fluorine. It occurs naturally as the mineral fluorite and as Blue John, and it is the source of most of the world's fluorine...
, calcium
tungstateIn chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate"...
and
strontiumStrontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
molybdateIn chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state.The...
, materials that are used in solid-state devices, and as a crystal stabilizer of
fuel cellA fuel cell is an electrochemical cell that produces electricity from a replenishable fuel tank. The electricity is generated through the reaction, triggered in the presence of an electrolyte, between the fuel and an oxidant . The reactants flow into the cell, and the reaction products flow out of...
s which operate at elevated temperatures. As a component of
Terfenol-DTerfenol-D is an alloy of the formula Tb Dy Fe, developed in the 1950's at the Naval Ordnance Laboratory in America. It is named after terbium, iron , Naval Ordnance Laboratory , and the D comes from dysprosium....
(an alloy which expands and contracts in magnetic field more than any other alloy), terbium is of use in
actuatorAn actuator is a mechanical device for moving or controlling a mechanism or system. An actuator typically is a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion....
s, in naval
sonarSonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels. There are two kinds of sonar: active and passive. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water...
systems and
sensorA sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass...
s. Terbium
oxideAn oxide is a chemical compound containing at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon...
is used in green
phosphorA phosphor is a substance that exhibits the phenomenon of phosphorescence ....
s in
fluorescent lampA fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light....
s and color TV tubes. Terbium "green" phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent
EuropiumEuropium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent of Europe.-Physical:Europium is about as hard as lead and quite ductile...
blue phosphors and trivalent europium red phosphors to provide the "trichromatic" lighting technology, which is by far the largest consumer of the world's terbium supply.
Physical
Terbium is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. It is relatively stable in air as compared to other lanthanides. Terbium exists in two crystal
allotropesAllotropy or allotropism is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner...
with a transformation temperature of 1289 °C between them.
The terbium(III) cation is brilliantly
fluorescentFluorescence is the emission of visible light by a substance that has absorbed light of a differing, usually invisible, wavelength. Absorption of a photon triggers the emission of a photon with a longer wavelength. A shorter wavelength emission is sometimes observed from multiple photon absorption...
, in a bright lemon-yellow color that is the result of a strong green emission line in combination with other lines in the orange and red. The yttrofluorite variety of the mineral
fluoriteFluorite is a halide mineral composed of calcium fluoride, CaF
2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Cubic crystals up to 20 cm across have been found at Dalnegorsk, Russia...
owes its creamy-yellow fluorescence in part to terbium. Terbium easily oxidizes and therefore used as element only for research purpose. For example, single Tb atoms have been isolated by implanting them into
fullereneA fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and cylindrical ones are called carbon nanotubes or buckytubes...
molecules.
Terbium has a simple ferromagnetic ordering at temperatures below 219 K. Above 219 K, it turns into an helical antiferromagnetic state in which all of the atomic moments in a particular basal plane layer are parallel, and oriented at a fixed angle to the moments of adjacent layers. This unusual antiferromagnetism transforms into a disordered (paramagnetic) state at 230 K.
Chemical
The most common valence state of terbium is +3, as in
{{infobox terbium}}
Terbium ({{pron-en|ˈtɜrbiəm}}, {{respell|TER|bee-əm}}) is a chemical elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
with the symbol
Tb and
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
65. It is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s, including
ceriteCerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the Ce rich species and the La rich species...
,
gadoliniteGadolinite is a mineral of a nearly black color and vitreous luster, and consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2FeBe2Si2O10...
,
monaziteMonazite is a reddish-brown phosphate mineral containing rare earth metals and is an important source of thorium, lanthanum, and cerium. It occurs usually in small isolated crystals...
,
xenotimeXenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
and
euxeniteEuxenite or euxenite- is a brownish black mineral with a metallic luster. It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: 2O6. It occurs in granite pegmatites and detrital...
.
Terbium is used to
dopeA dopant, also called doping agent and dope, is an impurity element added to a crystal lattice in low concentrations in order to alter the optical/electrical properties of the crystal....
calcium fluorideCalcium fluoride is an insoluble ionic compound of calcium and fluorine. It occurs naturally as the mineral fluorite and as Blue John, and it is the source of most of the world's fluorine...
, calcium
tungstateIn chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate"...
and
strontiumStrontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
molybdateIn chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state.The...
, materials that are used in solid-state devices, and as a crystal stabilizer of
fuel cellA fuel cell is an electrochemical cell that produces electricity from a replenishable fuel tank. The electricity is generated through the reaction, triggered in the presence of an electrolyte, between the fuel and an oxidant . The reactants flow into the cell, and the reaction products flow out of...
s which operate at elevated temperatures. As a component of
Terfenol-DTerfenol-D is an alloy of the formula Tb Dy Fe, developed in the 1950's at the Naval Ordnance Laboratory in America. It is named after terbium, iron , Naval Ordnance Laboratory , and the D comes from dysprosium....
(an alloy which expands and contracts in magnetic field more than any other alloy), terbium is of use in
actuatorAn actuator is a mechanical device for moving or controlling a mechanism or system. An actuator typically is a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion....
s, in naval
sonarSonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels. There are two kinds of sonar: active and passive. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water...
systems and
sensorA sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass...
s. Terbium
oxideAn oxide is a chemical compound containing at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon...
is used in green
phosphorA phosphor is a substance that exhibits the phenomenon of phosphorescence ....
s in
fluorescent lampA fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light....
s and color TV tubes. Terbium "green" phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent
EuropiumEuropium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent of Europe.-Physical:Europium is about as hard as lead and quite ductile...
blue phosphors and trivalent europium red phosphors to provide the "trichromatic" lighting technology, which is by far the largest consumer of the world's terbium supply.
Physical
Terbium is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. It is relatively stable in air as compared to other lanthanides. Terbium exists in two crystal
allotropesAllotropy or allotropism is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner...
with a transformation temperature of 1289 °C between them.
The terbium(III) cation is brilliantly
fluorescentFluorescence is the emission of visible light by a substance that has absorbed light of a differing, usually invisible, wavelength. Absorption of a photon triggers the emission of a photon with a longer wavelength. A shorter wavelength emission is sometimes observed from multiple photon absorption...
, in a bright lemon-yellow color that is the result of a strong green emission line in combination with other lines in the orange and red. The yttrofluorite variety of the mineral
fluoriteFluorite is a halide mineral composed of calcium fluoride, CaF
2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Cubic crystals up to 20 cm across have been found at Dalnegorsk, Russia...
owes its creamy-yellow fluorescence in part to terbium. Terbium easily oxidizes and therefore used as element only for research purpose. For example, single Tb atoms have been isolated by implanting them into
fullereneA fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and cylindrical ones are called carbon nanotubes or buckytubes...
molecules.
Terbium has a simple ferromagnetic ordering at temperatures below 219 K. Above 219 K, it turns into an helical antiferromagnetic state in which all of the atomic moments in a particular basal plane layer are parallel, and oriented at a fixed angle to the moments of adjacent layers. This unusual antiferromagnetism transforms into a disordered (paramagnetic) state at 230 K.
Chemical
The most common valence state of terbium is +3, as in
{{infobox terbium}}
Terbium ({{pron-en|ˈtɜrbiəm}}, {{respell|TER|bee-əm}}) is a chemical elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
with the symbol
Tb and
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
65. It is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s, including
ceriteCerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the Ce rich species and the La rich species...
,
gadoliniteGadolinite is a mineral of a nearly black color and vitreous luster, and consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2FeBe2Si2O10...
,
monaziteMonazite is a reddish-brown phosphate mineral containing rare earth metals and is an important source of thorium, lanthanum, and cerium. It occurs usually in small isolated crystals...
,
xenotimeXenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
and
euxeniteEuxenite or euxenite- is a brownish black mineral with a metallic luster. It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: 2O6. It occurs in granite pegmatites and detrital...
.
Terbium is used to
dopeA dopant, also called doping agent and dope, is an impurity element added to a crystal lattice in low concentrations in order to alter the optical/electrical properties of the crystal....
calcium fluorideCalcium fluoride is an insoluble ionic compound of calcium and fluorine. It occurs naturally as the mineral fluorite and as Blue John, and it is the source of most of the world's fluorine...
, calcium
tungstateIn chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate"...
and
strontiumStrontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
molybdateIn chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state.The...
, materials that are used in solid-state devices, and as a crystal stabilizer of
fuel cellA fuel cell is an electrochemical cell that produces electricity from a replenishable fuel tank. The electricity is generated through the reaction, triggered in the presence of an electrolyte, between the fuel and an oxidant . The reactants flow into the cell, and the reaction products flow out of...
s which operate at elevated temperatures. As a component of
Terfenol-DTerfenol-D is an alloy of the formula Tb Dy Fe, developed in the 1950's at the Naval Ordnance Laboratory in America. It is named after terbium, iron , Naval Ordnance Laboratory , and the D comes from dysprosium....
(an alloy which expands and contracts in magnetic field more than any other alloy), terbium is of use in
actuatorAn actuator is a mechanical device for moving or controlling a mechanism or system. An actuator typically is a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion....
s, in naval
sonarSonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels. There are two kinds of sonar: active and passive. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water...
systems and
sensorA sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass...
s. Terbium
oxideAn oxide is a chemical compound containing at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon...
is used in green
phosphorA phosphor is a substance that exhibits the phenomenon of phosphorescence ....
s in
fluorescent lampA fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light....
s and color TV tubes. Terbium "green" phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent
EuropiumEuropium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent of Europe.-Physical:Europium is about as hard as lead and quite ductile...
blue phosphors and trivalent europium red phosphors to provide the "trichromatic" lighting technology, which is by far the largest consumer of the world's terbium supply.
Physical
Terbium is a silvery-white
rare earthAs defined by 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...
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
that is malleable, ductile and soft enough to be cut with a knife. It is relatively stable in air as compared to other lanthanides. Terbium exists in two crystal
allotropesAllotropy or allotropism is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner...
with a transformation temperature of 1289 °C between them.
The terbium(III) cation is brilliantly
fluorescentFluorescence is the emission of visible light by a substance that has absorbed light of a differing, usually invisible, wavelength. Absorption of a photon triggers the emission of a photon with a longer wavelength. A shorter wavelength emission is sometimes observed from multiple photon absorption...
, in a bright lemon-yellow color that is the result of a strong green emission line in combination with other lines in the orange and red. The yttrofluorite variety of the mineral
fluoriteFluorite is a halide mineral composed of calcium fluoride, CaF
2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Cubic crystals up to 20 cm across have been found at Dalnegorsk, Russia...
owes its creamy-yellow fluorescence in part to terbium. Terbium easily oxidizes and therefore used as element only for research purpose. For example, single Tb atoms have been isolated by implanting them into
fullereneA fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and cylindrical ones are called carbon nanotubes or buckytubes...
molecules.
Terbium has a simple ferromagnetic ordering at temperatures below 219 K. Above 219 K, it turns into an helical antiferromagnetic state in which all of the atomic moments in a particular basal plane layer are parallel, and oriented at a fixed angle to the moments of adjacent layers. This unusual antiferromagnetism transforms into a disordered (paramagnetic) state at 230 K.
Chemical
The most common valence state of terbium is +3, as in
{{chemTerbium oxide, also known as terbium sesquioxide, is a sesquioxide of the rare earth metal terbium, having chemical formula . It is a p-type semiconductor, and may be prepared by the reduction of in hydrogen at 1300°C for 24 hours....
. The +4 state is known in TbO
2 and TbF
4.
Terbium burns readily to form a mixed
terbium(III,IV) oxideTerbium oxide, occasionally called tetraterbium heptaoxide, has the formula Tb4O7, though some texts refer to it as TbO1.75. There is some debate as to whether it is a discrete compound, or simply one phase in an interstitial oxide system...
:
- 8 Tb + 7 O2 → 2 Tb4O7
In solution, terbium forms only trivalent ions. Terbium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form terbium hydroxide:
- 2 Tb (s) + 6 H2O (l) → 2 Tb(OH)3 (aq) + 3H2 (g)
Terbium metal reacts with all the halogens:
- 2 Tb (s) + 3 F2 (g) → 2 TbF3 (s) [white]
- 2 Tb (s) + 3 Cl2 (g) → 2 TbCl3 (s) [white]
- 2 Tb (s) + 3 Br2 (g) → 2 TbBr3 (s) [white]
- 2 Tb (s) + 3 I2 (g) → 2 TbI3 (s)
Terbium dissolves readily in dilute
sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
to form solutions containing the pale pink Tb(III) ions, which exist as a [Tb(OH
2)
9]
3+ complexes:
- 2 Tb (s) + 3 H2SO4 (aq) → 2 Tb3+ (aq) + 3 {{chem|SO|4|2-}} (aq) + 3 H2 (g)
Compounds
{{seealso|Category:Terbium compounds}}
Terbium combines with nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon and arsenic at elevated temperatures, forming various binary compounds such as TbH
2, TBH
3, TbB
2, Tb
2S
3, TbSe, TbTe and TbN. In those compounds, Tb mostly exhibit oxidation states +3 and sometimes +2. Terbium(II) halogenides are obtained by annealing Tb(III) halogenides in presence of metallic Tb in tantalum containers. Terbium also form sesquichloride Tb
2Cl
3, which can be further reduced to TbCl by annealing at 800 °C. This terbium(I) chloride forms platelets with layered graphite-like structure.
Other compounds include
- Chloride
The chloride ion is formed when the element chlorine picks up one electron to form an anion Cl
−...
s: TbCl3Terbium chloride is a chemical compound. In the solid state TbCl3 has the YCl3 layer structure. Terbium chloride frequently forms a hexahydrate.-Hazards:Terbium chloride causes hyperemia of the iris....
- Bromide
A bromide ion is a bromine atom with 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: TbBr3Terbium bromide is a chemical compound....
- Iodide
An iodide ion is an iodine atom with a −1 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. This is the same naming scheme as is seen with chlorides...
s: TbI3Terbium iodide is an inorganic chemical compound....
- Fluoride
Fluoride is the anion F
−, the reduced form of fluorine. Both organic and inorganic compounds containing the element fluorine are sometimes called fluorides. Fluoride, like other halides, is a monovalent ion . Its compounds often have properties that are distinct relative to other...
s: TbF3, TbF4
Terbium(IV) fluoride is a strong fluorinating agent, emitting relatively pure atomic fluorine when heated rather than the mixture of fluoride vapors emitted from CoF
3 or CeF
4.
Isotopes
{{main|isotopes of terbium}}
Naturally occurring terbium is composed of 1 stable
isotopeIsotopes are different types of atoms of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number but not in atomic number. The difference in the number of nucleons comes from a difference how many neutrons are in the atomic nucleus...
,
159Tb. 33 radioisotopes have been characterized, with the most stable being
158Tb with a
half-lifeHalf-life is the period of time, for a substance undergoing decay, to decrease by half. The name originally was used to describe a characteristic of unstable atoms , but may apply to any quantity which follows a set-rate decay....
of 180 years,
157Tb with a half-life of 71 years, and
160Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lives that are less than 6.907 days, and the majority of these have half-lives that are less than 24 seconds. This element also has 18 meta states, with the most stable being
156m1Tb (t
½ 24.4 hours),
154m2Tb (t
½ 22.7 hours) and
154m1Tb (t
½ 9.4 hours).
The primary decay mode before the most abundant stable isotope,
159Tb, is
electron captureElectron capture is a decay mode for isotopes that will occur when there are too many protons in the 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 after is beta minus decay. The primary
decay productIn nuclear physics, a decay product is a nuclide produced by radioactive decay. Radioactive decay often involves a sequence of steps...
s before
159Tb are element Gd (
gadoliniumGadolinium is a chemical element that has the symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. Gadolinium has exceptionally high absorption of neutrons and therefore is used for shielding in neutron radiography and in nuclear reactors...
) isotopes, and the primary products after are element Dy (
dysprosiumDysprosium is a chemical element with the symbol Dy and atomic number 66. It is a rare earth element with a metallic silver luster. Dysprosium is never found in nature as a free element, though it is found in various minerals, such as xenotime...
) isotopes.
History
Terbium was discovered in 1843 by
SwedishSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
chemistA 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. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component...
Carl Gustaf MosanderCarl Gustaf Mosander was a Swedish chemist. He discovered the elements lanthanum, erbium and terbium....
,
who detected it as an impurity in Yttrium oxide, Y
2O
3, and named after the village
YtterbyYtterby is a village on the Swedish island of Resarö, in Vaxholm Municipality in the Stockholm archipelago.Lending its name to a famous quarry where many rare earth minerals have been discovered, the small village has been the inspiration for naming four of the chemical elements: yttrium ,...
in
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
. It was not isolated in pure form until the recent advent of
ion exchangeIon 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...
techniques.
When Mosander first partitioned "yttria" into three fractions, "terbia" was the fraction that contained the pink color (due to what is now known as erbium), and "erbia" was the fraction that was essentially colorless in solution, but gave a brown-tinged oxide. Later workers had difficulty in observing the latter, but the pink fraction was impossible to miss. Arguments went back and forth as to whether "erbia" even existed. In the confusion, the original names got reversed, and the exchange of names stuck. It is now thought that those workers who used the double sodium or potassium sulfates to remove "ceria" from "yttria" inadvertently lost the terbium content of the system into the ceria-containing precipitate. In any case, what is now known as terbium was only about 1% of the original yttria, but that was sufficient to impart a yellowish color to the oxide. Thus, terbium was a minor component in the original terbium fraction, dominated by its immediate neighbors,
gadoliniumGadolinium is a chemical element that has the symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. Gadolinium has exceptionally high absorption of neutrons and therefore is used for shielding in neutron radiography and in nuclear reactors...
and
dysprosiumDysprosium is a chemical element with the symbol Dy and atomic number 66. It is a rare earth element with a metallic silver luster. Dysprosium is never found in nature as a free element, though it is found in various minerals, such as xenotime...
. Thereafter, whenever other rare earths were teased apart from this mixture, whichever fraction gave the brown oxide retained the terbium name, until at last it was pure. The 19th century investigators did not have the benefit of fluorescence technology, wherewith to observe the brilliant fluorescence that would have made this element much easier to track in mixtures.
Occurrence
Terbium is never found in nature as a free element, but it is contained in many
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s, including
ceriteCerite is a complex silicate mineral group containing cerium, formula 963. The cerium and lanthanum content varies with the Ce rich species and the La rich species...
,
gadoliniteGadolinite is a mineral of a nearly black color and vitreous luster, and consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with formula: 2FeBe2Si2O10...
,
monaziteMonazite is a reddish-brown phosphate mineral containing rare earth metals and is an important source of thorium, lanthanum, and cerium. It occurs usually in small isolated crystals...
((Ce,La,Th,Nd,Y)PO
4, which contains up to 0.03% of terbium),
xenotimeXenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
(YPO
4) and
euxeniteEuxenite or euxenite- is a brownish black mineral with a metallic luster. It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: 2O6. It occurs in granite pegmatites and detrital...
((Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)
2O
6, which contains 1% or more of terbium). The crust abundance of terbium is estimated as 1.2 mg/kg.
The richest current commercial sources of terbium are the ion-adsorption
clayClay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired...
s of southern China. The high-yttrium concentrate versions of these are about two-thirds yttrium oxide by weight, and about 1% terbia. However, small amounts occur in
bastnäsiteThe mineral bastnäsite is one of a family of three carbonate-fluoride minerals. There is bastnäsite- with a formula of CO3F. There is bastnäsite- with a formula of CO3F. There is also bastnäsite- with a formula of CO3F...
and monazite, and when these are processed by solvent-extraction to recover the valuable heavy lanthanides in the form of "
samariumSamarium is a chemical element with the symbol Sm and atomic number 62.-Physical:Samarium is a rare earth metal, with a bright silver luster. Three crystal modifications of the metal also exist, with transformations at 734 and 922 °C, making it polymorphic...
-
europiumEuropium is a chemical element with the symbol Eu and atomic number 63. It was named after the continent of Europe.-Physical:Europium is about as hard as lead and quite ductile...
-
gadoliniumGadolinium is a chemical element that has the symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. Gadolinium has exceptionally high absorption of neutrons and therefore is used for shielding in neutron radiography and in nuclear reactors...
concentrate" (
SEG concentrate), the terbium content of the ore ends up therein. Due to the large volumes of bastnäsite processed, relative to the richer ion-adsorption clays, a significant proportion of the world's terbium supply comes from bastnäsite.
Production
Crushed terbium-containing minerals are treated with hot concentrated
sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
to produce water-soluble sulfates of rare earths. The acidic filtrates are partially neutralized with caustic soda to pH 3-4.
ThoriumThorium is a chemical element with the symbol Th and atomic number 90. It is a naturally occurring, slightly radioactive metal. Thorium is estimated to be about three to four times more abundant than uranium in the earth's crust...
precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths into their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in
nitric acidNitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure older samples tend to acquire a stronger yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as...
that excludes one of the main components, cerium, whose oxide is insoluble in HNO
3. Terbium is separated as a double salt with ammonium nitrate by crystallization.
The most efficient separation routine for terbium salt from the rare-earth salt solution is
ion exchangeIon 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...
. In this process, rare-earth ions are sorbed onto suitable ion-exchange resin by exchange with hydrogen, ammonium or cupric ions present in the resin. The rare earth ions are then selectively washed out by suitable complexing agent. As with other rare earths, terbium metal is produced by reducing the anhydrous chloride or fluoride with calcium metal. Calcium and tantalum impurities can be removed by vacuum remelting, distillation, amalgam formation or
zone meltingZone melting is a group of similar methods of purifying crystals, in which a narrow region of a crystal is molten, and this molten zone is moved along the crystal...
.
Applications
Terbium is used to
dopeA dopant, also called doping agent and dope, is an impurity element added to a crystal lattice in low concentrations in order to alter the optical/electrical properties of the crystal....
calcium fluorideCalcium fluoride is an insoluble ionic compound of calcium and fluorine. It occurs naturally as the mineral fluorite and as Blue John, and it is the source of most of the world's fluorine...
, calcium
tungstateIn chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate"...
and
strontiumStrontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
molybdateIn chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state.The...
, materials that are used in solid-state devices, and as a crystal stabilizer of
fuel cellA fuel cell is an electrochemical cell that produces electricity from a replenishable fuel tank. The electricity is generated through the reaction, triggered in the presence of an electrolyte, between the fuel and an oxidant . The reactants flow into the cell, and the reaction products flow out of...
s which operate at elevated temperatures, together with ZrO
2.
Terbium is also used in
alloyAn alloy is a partial or complete solid solution of one or more elements 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 and in the production of electronic devices. As a component of
Terfenol-DTerfenol-D is an alloy of the formula Tb Dy Fe, developed in the 1950's at the Naval Ordnance Laboratory in America. It is named after terbium, iron , Naval Ordnance Laboratory , and the D comes from dysprosium....
, terbium is of use in
actuatorAn actuator is a mechanical device for moving or controlling a mechanism or system. An actuator typically is a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion....
s, in naval
sonarSonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels. There are two kinds of sonar: active and passive. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water...
systems,
sensorA sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass...
s, in the
SoundBugSoundbug is a small device that can turn any resonant flat surface into a distributed mode loudspeaker , allowing one to listen to media devices without using traditional speakers. Devices such as mp3 players, cd players, and computers can be used, by plugging the Soundbug into any headphone jack...
device (its first commercial application), and other magnetomechanical devices. Terfenol-D is an alloy that expands or contracts in the presence of a magnetic field. It has the highest
magnetostrictionMagnetostriction is a property of ferromagnetic materials that causes them to change their shape when subjected to a magnetic field. The effect was first identified in 1842 by James Joule when observing a sample of nickel...
of any
alloyAn alloy is a partial or complete solid solution of one or more elements 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...
.
Terbium
oxideAn oxide is a chemical compound containing at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon...
is used in green
phosphorA phosphor is a substance that exhibits the phenomenon of phosphorescence ....
s in fluorescent lamps and color TV tubes.
SodiumSodium is a metallic element with a symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals within "group 1"...
terbium
borateBorates in chemistry are chemical compounds containing boron oxoanions, with boron in oxidation state +3. The simplest borate ion is the trigonal planar, BO33−, although many others are known. BO33− forms salts with metallic elements. Boron found in...
is used in
solid stateSolid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...
devices. The brilliant fluorescence allows terbium to be used as a probe in biochemistry, where it somewhat resembles
calciumCalcium 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...
in its behavior. Terbium "green" phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent Europium blue phosphors and trivalent europium red phosphors to provide the "trichromatic" lighting technology, which is by far the largest consumer of the world's terbium supply. Trichromatic lighting provides much higher light output for a given amount of electrical energy than does incandescent lighting.
Precautions
As with the other
lanthanideAccording to the IUPAC terminology, the lanthanoid series comprises the fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium. All lanthanoids are f-block elements, corresponding to the filling of the 4f electron shell, except for lutetium which is a d-block lanthanoid...
s, terbium compounds are of low to moderate toxicity, although their toxicity has not been investigated in detail. Terbium has no known biological role.
External links
{{Commons|Terbium}}
{{wiktionary|terbium}}
{{clear}}
{{Compact periodic table}}
{{Terbium compounds}}