Holmium 166m Oxide
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Holmium is a
chemical element A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its ...
; it has
symbol A symbol is a mark, Sign (semiotics), sign, or word that indicates, signifies, or is understood as representing an idea, physical object, object, or wikt:relationship, relationship. Symbols allow people to go beyond what is known or seen by cr ...
Ho and
atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (''n''p) or the number of pro ...
67. It is a
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
and the eleventh member of the
lanthanide series The lanthanide () or lanthanoid () series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium (e ...
. It is a relatively soft, silvery, fairly
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
-resistant and
malleable Ductility refers to the ability of a material to sustain significant plastic deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic deformation, which is reversi ...
metal. Like many other lanthanides, holmium is too reactive to be found in native form, as pure holmium slowly forms a yellowish
oxide An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation st ...
coating when exposed to air. When isolated, holmium is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and also burns in air when heated. In nature, holmium occurs together with the other rare-earth metals (like
thulium Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. It i ...
). It is a relatively rare lanthanide, making up 1.4
parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since t ...
of the
Earth's crust Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper ...
, an abundance similar to
tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...
. Holmium was discovered through isolation by Swedish chemist
Per Theodor Cleve Per Teodor Cleve (10 February 1840 – 18 June 1905) was a Swedish chemist, biologist, mineralogist and oceanographer. He is best known for his discovery of the chemical elements holmium and thulium. Born in Stockholm in 1840, Cleve earned his ...
. It was also independently discovered by Jacques-Louis Soret and
Marc Delafontaine Marc Delafontaine (March 31, 1837/1838, Céligny, Switzerland–1911) was a Switzerland, Swiss chemist and spectroscopist who was involved in discovering and investigating some of the rare earth elements. Career Delafontaine studied with Jean C ...
, who together observed it spectroscopically in 1878. Its oxide was first isolated from rare-earth ores by Cleve in 1878. The element's name comes from ''Holmia'', the Latin name for the city of
Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...
. Like many other
lanthanides The lanthanide () or lanthanoid () series of chemical elements comprises at least the 14 Metal, metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium ...
, holmium is found in the minerals monazite and
gadolinite Gadolinite, sometimes known as ytterbite, is a silicate mineral consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula . It is called gadolinite-(Ce) or gadolinite-(Y), depending o ...
and is usually commercially extracted from monazite using ion-exchange techniques. Its compounds in nature and in nearly all of its laboratory chemistry are trivalently oxidized, containing Ho(III)
ions An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
. Trivalent holmium ions have
fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...
properties similar to many other rare-earth ions (while yielding their own set of unique emission light lines), and thus are used in the same way as some other rare earths in certain
laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...
and glass-colorant applications. Holmium has the highest
magnetic permeability In electromagnetism, permeability is the measure of magnetization produced in a material in response to an applied magnetic field. Permeability is typically represented by the (italicized) Greek letter ''μ''. It is the ratio of the magnetic ...
and magnetic saturation of any element and is thus used for the pole pieces of the strongest static
magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...
s. Because holmium strongly absorbs
neutrons The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the f ...
, it is also used as a burnable poison in
nuclear reactors A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. Fissile nuclei (primarily uranium-235 or plutonium-2 ...
.


Properties

Holmium is the eleventh member of the
lanthanide The lanthanide () or lanthanoid () series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium (el ...
series. In the periodic table, it appears in period 6, between the lanthanides
dysprosium Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it ...
to its left and
erbium Erbium is a chemical element; it has Symbol (chemistry), symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare- ...
to its right, and above the
actinide The actinide () or actinoid () series encompasses at least the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through nobelium. Number 103, lawrencium, is also generally included despite being part ...
einsteinium Einsteinium is a synthetic chemical element; it has symbol Es and atomic number 99 and is a member of the actinide series and the seventh transuranium element. Einsteinium was discovered as a component of the debris of the first hydrogen bomb ...
.


Physical properties

With a boiling point of , holmium is the sixth most volatile lanthanide after
ytterbium Ytterbium is a chemical element; it has symbol Yb and atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. Like the other lanthani ...
,
europium Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and soft ...
, samarium,
thulium Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. It i ...
and
dysprosium Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it ...
. At standard temperature and pressure, holmium, like many of the second half of the lanthanides, normally assumes a hexagonally close-packed (hcp) structure. Its 67
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
s are arranged in the configuration e4f11 6s2, so that it has thirteen
valence electron In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond, a shared pair forms with b ...
s filling the 4f and 6s subshells. Holmium, like all of the lanthanides, is
paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...
at standard temperature and pressure. However, holmium is
ferromagnetic Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet. Ferromagne ...
at temperatures below . It has the highest
magnetic moment In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field. The magnetic dipole moment of an object determines the magnitude ...
() of any naturally occurring element and possesses other unusual magnetic properties. When combined with
yttrium Yttrium is a chemical element; it has Symbol (chemistry), symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost a ...
, it forms highly
magnetic Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...
compounds.


Chemical properties

Holmium metal tarnishes slowly in air, forming a yellowish oxide layer that has an appearance similar to that of
iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
rust. It burns readily to form holmium(III) oxide: :4 Ho + 3 O2 → 2 Ho2O3 It is a relatively soft and
malleable Ductility refers to the ability of a material to sustain significant plastic deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic deformation, which is reversi ...
element that is fairly
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
-resistant and chemically stable in dry air at
standard temperature and pressure Standard temperature and pressure (STP) or standard conditions for temperature and pressure are various standard sets of conditions for experimental measurements used to allow comparisons to be made between different sets of data. The most used ...
. In moist air and at higher temperatures, however, it quickly oxidizes, forming a yellowish oxide. In pure form, holmium possesses a metallic, bright silvery luster. Holmium is quite electropositive: on the Pauling
electronegativity Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...
scale, it has an electronegativity of 1.23. It is generally trivalent. It reacts slowly with cold water and quickly with hot water to form holmium(III) hydroxide: :2 Ho (s) + 6 H2O (l) → 2 Ho(OH)3 (aq) + 3 H2 (g) Holmium metal reacts with all the stable
halogen The halogens () are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would ...
s: :2 Ho (s) + 3 F2 (g) → 2 HoF3 (s) ink :2 Ho (s) + 3 Cl2 (g) → 2 HoCl3 (s) ellow :2 Ho (s) + 3 Br2 (g) → 2 HoBr3 (s) ellow :2 Ho (s) + 3 I2 (g) → 2 HoI3 (s) ellow Holmium dissolves readily in dilute
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
to form
solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solu ...
s containing the yellow Ho(III) ions, which exist as a o(OH2)9sup>3+ complexes: :2 Ho (s) + 3 H2SO4 (aq) → 2 Ho3+ (aq) + 3 (aq) + 3 H2 (g)


Oxidation states

As with many lanthanides, holmium is usually found in the +3
oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...
, forming compounds such as holmium(III) fluoride (HoF3) and holmium(III) chloride (HoCl3). Holmium in solution is in the form of Ho3+ surrounded by nine molecules of water. Holmium dissolves in
acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...
s. However, holmium is also found to exist in +2, +1 and 0 oxidation states.


Isotopes

The isotopes of holmium range from 140Ho to 175Ho. The primary
decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
before the most abundant
stable isotope Stable nuclides are Isotope, isotopes of a chemical element whose Nucleon, nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The Atomic nucleus, nuclei of such isotopes are no ...
, 165Ho, is
positron emission Positron emission, beta plus decay, or β+ decay is a subtype of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (). Positron emi ...
, and the primary mode after is beta minus decay. The primary
decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...
s before 165Ho are
terbium Terbium is a chemical element; it has Symbol (chemistry), symbol Tb and atomic number 65. It is a silvery-white, rare earth element, rare earth metal that is malleable and ductile. The ninth member of the lanthanide series, terbium is a fairly ele ...
and
dysprosium Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it ...
isotopes, and the primary products after are
erbium Erbium is a chemical element; it has Symbol (chemistry), symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare- ...
isotopes. Natural holmium consists of one
primordial isotope In geochemistry, geophysics and nuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed. Primordial nuclides were present in the ...
, holmium-165; it is the only isotope of holmium that is thought to be stable, although it is predicted to undergo
alpha decay Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus). The parent nucleus transforms or "decays" into a daughter product, with a mass number that is reduced by four and an a ...
to terbium-161 with a very long half-life. Of the 35
synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...
radioactive isotopes that are known, the most stable one is holmium-163 (163Ho), with a half-life of 4570 years. All other radioisotopes have ground-state half-lives not greater than 1.117 days, with the longest, holmium-166 (166Ho) having a half-life of 26.83 hours, and most have half-lives under 3 hours. 166m1Ho has a half-life of around 1200 years. The high excitation energy, resulting in a particularly rich spectrum of decay
gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...
s produced when the metastable state de-excites, makes this isotope useful as a means for calibrating
gamma ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and techni ...
s.


Compounds


Oxides and chalcogenides

Holmium(III) oxide is the only oxide of holmium. It changes its color depending on the lighting conditions. In daylight, it has a yellowish color. Under trichromatic light, it appears orange red, almost indistinguishable from the appearance of erbium oxide under the same lighting conditions. The color change is related to the sharp
emission lines A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...
of trivalent holmium ions acting as red phosphors. Holmium(III) oxide appears pink under a cold-cathode fluorescent lamp. Other
chalcogenide : 220px, Cadmium sulfide, a prototypical metal chalcogenide, is used as a yellow pigment. A chalcogenide is a chemical compound consisting of at least one chalcogen anion and at least one more electropositive element. Although all group 16 elemen ...
s are known for holmium. Holmium(III) sulfide has orange-yellow
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
s in the
monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic sy ...
, with the
space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...
''P''21/''m'' (No. 11). Under high pressure, holmium(III) sulfide can form in the
cubic Cubic may refer to: Science and mathematics * Cube (algebra), "cubic" measurement * Cube, a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex ** Cubic crystal system, a crystal system w ...
and
orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...
crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices (an infinite array of discrete points). Space groups (symmetry groups ...
s. It can be obtained by the reaction of holmium(III) oxide and
hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...
at . Holmium(III) selenide is also known. It is antiferromagnetic below 6 K.


Halides

All four trihalides of holmium are known. Holmium(III) fluoride is a yellowish powder that can be produced by reacting holmium(III) oxide and ammonium fluoride, then crystallising it from the ammonium
salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
formed in solution. Holmium(III) chloride can be prepared in a similar way, with
ammonium chloride Ammonium chloride is an inorganic chemical compound with the chemical formula , also written as . It is an ammonium salt of hydrogen chloride. It consists of ammonium cations and chloride anions . It is a white crystalline salt (chemistry), sal ...
instead of ammonium fluoride. It has the YCl3 layer structure in the solid state. These compounds, as well as holmium(III) bromide and holmium(III) iodide, can be obtained by the direct reaction of the elements: :2 Ho + 3 X2 → 2 HoX3 In addition, holmium(III) iodide can be obtained by the direct reaction of holmium and mercury(II) iodide, then removing the mercury by
distillation Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...
.


Organoholmium compounds

Organoholmium compounds are very similar to those of the other lanthanides, as they all share an inability to undergo π backbonding. They are thus mostly restricted to the mostly ionic cyclopentadienides ( isostructural with those of lanthanum) and the σ-bonded simple
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...
s and
aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used ...
s, some of which may be polymeric.Greenwood and Earnshaw, pp. 12481249


History

Holmium (,
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
name for
Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...
) was discovered by the Swiss chemists Jacques-Louis Soret and
Marc Delafontaine Marc Delafontaine (March 31, 1837/1838, Céligny, Switzerland–1911) was a Switzerland, Swiss chemist and spectroscopist who was involved in discovering and investigating some of the rare earth elements. Career Delafontaine studied with Jean C ...
in 1878 who noticed the aberrant spectrographic
emission spectrum The emission spectrum of a chemical element or chemical compound is the Spectrum (physical sciences), spectrum of frequencies of electromagnetic radiation emitted due to electrons making a atomic electron transition, transition from a high energ ...
of the then-unknown element (they called it "Element X"). The Swedish chemist
Per Teodor Cleve Per Teodor Cleve (10 February 1840 – 18 June 1905) was a Swedish chemist, biologist, mineralogist and oceanographer. He is best known for his discovery of the chemical elements holmium and thulium. Born in Stockholm in 1840, Cleve earned ...
also independently discovered the element while he was working on erbia earth ( erbium oxide). He was the first to isolate impure oxide of the new element. Using the method developed by the Swedish chemist Carl Gustaf Mosander, Cleve first removed all of the known contaminants from erbia. The result of that effort was two new materials, one brown and one green. He named the brown substance ''holmia'' (after the Latin name for Cleve's home town, Stockholm) and the green one ''thulia''. ''Holmia'' was later found to be the holmium oxide, and ''thulia'' was
thulium oxide Thulium(III) oxide is a pale green crystalline compound, with the formula thulium, Tm2oxygen, O3. It was first isolated in 1879, from an impure sample of erbia, by Sweden, Swedish chemist Per Teodor Cleve, who named it ''thulia''. Synthesis Thu ...
. The pure oxide was only isolated in 1911 and the metal in 1939 by Heinrich Bommer. In the English physicist Henry Moseley's classic paper on
atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (''n''p) or the number of pro ...
s, holmium was assigned the value 66. The holmium preparation he had been given to investigate had been impure, dominated by neighboring dysprosium. He would have seen x-ray emission lines for both elements, but assumed that the dominant ones belonged to holmium, instead of the dysprosium impurity.


Occurrence and production

Like all the other
rare-earth element The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
s, holmium is not naturally found as a
free element In chemistry, a free element is a chemical element that is not combined with or chemically bonded to other elements. Examples of elements which can occur as free elements include the molecular oxygen (O) and carbon as diamond or graphite.A. Earn ...
. It occurs combined with other elements in gadolinite, monazite and other rare-earth minerals. No holmium-dominant mineral has yet been found. The main mining areas are China, United States, Brazil, India, Sri Lanka, and Australia with reserves of holmium estimated as 400,000 tonnes. The annual production of holmium metal is of about 10 tonnes per year. Holmium makes up 1.3 parts per million of the
Earth's crust Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper ...
by mass.ABUNDANCE OF ELEMENTS IN THE EARTH’S CRUST AND IN THE SEA, ''CRC Handbook of Chemistry and Physics,'' 97th edition (2016–2017), p. 14-17 Holmium makes up 1 part per million of the
soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
s, 400 parts per
quadrillion Depending on context (e.g. language, culture, region), some large numbers have names that allow for describing large quantities in a textual form; not mathematical. For very large values, the text is generally shorter than a decimal numeric repres ...
of seawater, and almost none of
Earth's atmosphere The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weathe ...
, which is very rare for a lanthanide. It makes up 500 parts per trillion of the universe by mass. Holmium is commercially extracted by
ion exchange Ion exchange is a reversible interchange of one species of ion present in an insoluble solid with another of like charge present in a solution surrounding the solid. Ion exchange is used in softening or demineralizing of water, purification of ch ...
from monazite sand (0.05% holmium), but is still difficult to separate from other rare earths. The element has been isolated through the reduction of its
anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...
chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...
or
fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...
with metallic
calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
. Its estimated abundance in the Earth's crust is 1.3 mg/kg. Holmium obeys the Oddo–Harkins rule: as an odd-numbered element, it is less abundant than both dysprosium and erbium. However, it is the most abundant of the odd-numbered heavy
lanthanides The lanthanide () or lanthanoid () series of chemical elements comprises at least the 14 Metal, metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium ...
. Of the lanthanides, only
promethium Promethium is a chemical element; it has Symbol (chemistry), symbol Pm and atomic number 61. All of its isotopes are Radioactive decay, radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in the Earth's crust a ...
,
thulium Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. It i ...
, lutetium and terbium are less abundant on Earth. The principal current source are some of the ion-adsorption clays of southern China. Some of these have a rare-earth composition similar to that found in xenotime or gadolinite. Yttrium makes up about two-thirds of the total by mass; holmium is around 1.5%. Holmium is relatively inexpensive for a rare-earth metal with the price about 1000 
USD The United States dollar (symbol: $; currency code: USD) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it int ...
/kg.


Applications

Glass containing holmium oxide and holmium oxide solutions (usually in
perchloric acid Perchloric acid is a mineral acid with the formula H Cl O4. It is an oxoacid of chlorine. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid, nitric acid and hydrochloric acid. It is a powerful oxid ...
) have sharp optical absorption peaks in the spectral range 200 to 900 nm. They are therefore used as a calibration standard for optical spectrophotometers. The radioactive but long-lived 166m1Ho is used in calibration of
gamma-ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see Gamma spectroscopy#Scintillation detectors, figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of ...
s. Holmium is used to create the strongest artificially generated
magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...
s, when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator). Holmium is also used in the manufacture of some
permanent magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, c ...
s. Holmium can act as a sensitizer in sodium yttrium fluoride which takes advantage of its absorption in the NIR-II window. Holmium allows for lanthanide nanomaterials to have tunable emission and excitation in the NIR-II. Under 1143 nm excitation the interfacial energy transfer to other lanthanides allows a redshift in emission for biological applications. This allows deeper penetration than typically used 980 nm and 808 nm lasers. Holmium-doped
yttrium iron garnet Yttrium iron garnet (YIG) is a kind of synthetic garnet, with chemical composition , or Y3Fe5O12. It is a ferrimagnetic material with a Curie temperature of 560  K. YIG may also be known as yttrium ferrite garnet, or as iron yttrium oxide or ...
(YIG) and yttrium lithium fluoride have applications in
solid-state laser A solid-state laser is a laser that uses a active laser medium, gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as ...
s, and Ho-YIG has applications in optical isolators and in
microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
equipment (e.g., YIG spheres). Holmium lasers emit at 2.1 micrometres. They are used in medical, dental, and fiber-optical applications. It is also being considered for usage in the enucleation of the
prostate The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ...
. Since holmium can absorb
nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...
-bred neutrons, it is used as a burnable poison to regulate nuclear reactors. It is used as a
colorant A colourant/colour additive (British spelling) or colorant/color additive (American spelling) is a substance that is added or applied in order to change the colour of a material or surface. Colourants can be used for many purposes including printin ...
for
cubic zirconia Cubic zirconia (CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirc ...
, providing pink coloring, and for
glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
, providing yellow-orange coloring. In March 2017,
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
announced that they had developed a technique to store one
bit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...
of data on a single holmium atom set on a bed of
magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
. With sufficient quantum and classical control techniques, holmium may be a good candidate to make quantum computers. Holmium is used in the medical field, particularly in
laser surgery Laser surgery is a type of surgery that cuts tissue using a laser in contrast to using a scalpel. Soft-tissue laser surgery is used in a variety of applications in humans ( general surgery, neurosurgery, ENT, dentistry, orthodontics, and ...
for procedures such as kidney stone removal and prostate treatment, due to its precision and minimal tissue damage. Its
isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...
, holmium-166, is applied in targeted cancer therapies, especially for liver cancer, and it also enhances
MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...
imaging as a contrast agent.


Biological role and precautions

Holmium plays no biological role in humans, but its salts are able to stimulate
metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...
. Humans typically consume about a milligram of holmium a year. Plants do not readily take up holmium from the soil. Some vegetables have had their holmium content measured, and it amounted to 100 parts per trillion. Holmium and its soluble salts are slightly toxic if ingested, but insoluble holmium salts are nontoxic. Metallic holmium in dust form presents a fire and explosion hazard. Large amounts of holmium salts can cause severe damage if inhaled, consumed orally, or injected. The biological effects of holmium over a long period of time are not known. Holmium has a low level of
acute toxicity Acute toxicity describes the adverse effects of a substance that result either from a single exposure or from multiple exposures in a short period of time (usually less than 24 hours). To be described as ''acute'' toxicity, the adverse effect ...
.


See also

* :Holmium compounds *
Period 6 element A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the chemical elements, including the lanthanides. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the ...


References


Bibliography

* * * * * * * * * * *


Further reading

* R. J. Callow, ''The Industrial Chemistry of the Lanthanons, Yttrium, Thorium, and Uranium'', Pergamon Press, 1967.


External links


Holmium
at ''
The Periodic Table of Videos ''Periodic Videos'' (also known as ''The Periodic Table of Videos'') is a video project and YouTube channel on chemistry. It consists of a series of videos about chemical elements and the periodic table, with additional videos on other topics i ...
'' (University of Nottingham) {{Authority control Chemical elements Chemical elements with hexagonal close-packed structure Ferromagnetic materials Lanthanides Neutron poisons Reducing agents