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Holmium(III) oxide
Encyclopedia
Holmium oxide, or holmium oxide is a chemical compound
of a rare-earth element holmium
and oxygen
with the formula
Ho2O3. Together with dysprosium(III) oxide
(Dy2O3) holmium oxide is one of the most powerfully paramagnetic
substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral
called erbia. Typically the oxides of the trivalent lanthanide
s coexist in nature and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glass
es. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the visible spectral range
. They are therefore traditionally used as a convenient calibration standard for optical spectrophotometers
.
of 5.3 eV and thus should appear colorless. The yellow color originates from abundant lattice defects (such as oxygen vacancies) and is related to internal transitions at the Ho3+ ions.
Holmium oxide has a cubic
, yet rather complex structure, with many atoms per unit cell and a large lattice constant of 1.06 nm. This structure is characteristic of oxides of heavy rare-earth elements, such as Tb2O3, Dy2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3. The thermal expansion coefficient of Ho2O3 is also relatively large at 7.4 µm/°C.
or with ammonium chloride
affords the corresponding holmium chloride
:
name for Stockholm
) was discovered by Marc Delafontaine
and Jacques-Louis Soret
in 1878 who noticed the aberrant spectrographic
absorption band
s of the then-unknown element (they called it "Element X"). Later in 1878, Per Teodor Cleve
independently discovered the element while he was working on erbia earth (erbium oxide).
Using the method developed by 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.
Holmium oxide occurs in trace amounts in the minerals gadolinite
, monazite
, and in other rare-earth mineral
s. Holmium metal readily oxidizes in air; therefore presence of holmium in nature is synonymous with that of holmia. With the abundance of 1.4 mg/kg, holmium is the 56th most abundant element. The main mining areas are China
, United States
, Brazil
, India
, Sri Lanka
and Australia
with reserves of holmium oxide estimated as 400,000 tonnes.
to produce water-soluble sulfates of several rare earth elements. The acidic filtrates are partially neutralized with sodium hydroxide to pH 3-4. Thorium
precipitates out of solution as hydroxide and is removed. After that, the solution is treated with ammonium oxalate
to convert rare earths in to their insoluble oxalate
s. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid
that excludes one of the main components, cerium
, whose oxide is insoluble in HNO3.
The most efficient separation routine for holmium oxide from the rare-earths is ion exchange
. In this process, rare-earth ions are adsorbed 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, such as ammonium citrate or nitrilotracetate.
Holmium oxide is one of the colorants used for cubic zirconia
and glass
, providing yellow or red coloring. Glass containing holmium oxide and holmium oxide solutions (usually in perchloric acid
) have sharp optical absorption peaks in the spectral range 200-900 nm. They are therefore used as a calibration standard for optical spectrophotometers
and are available commercially. As most other oxides of rare-earth elements, holmium oxide is used as a specialty catalyst, phosphor
and a laser
material. Holmium laser operates at wavelength of about 2.08 micrometres, either in pulsed or continuous regime. This laser is eye safe and is used in medicine, LIDAR
s, wind velocity measurements and atmosphere monitoring.
and hemoglobinemia
. It has low oral, dermal and inhalation toxicities and is non-irritating. The acute oral median lethal dose (LD50) is greater than 1 g per kilogram of body weight.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
of a rare-earth element holmium
Holmium
Holmium is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a rare earth element. Its oxide was first isolated from rare earth ores in 1878 and the element was named after the city of Stockholm....
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Ho2O3. Together with dysprosium(III) oxide
Dysprosium(III) oxide
Dysprosium Oxide is a white, slightly hygroscopic powder having specialized uses in ceramics, glass, phosphors, lasers and dysprosium metal halide lamps.It can react with acids to produce the corresponding dysprosium salts:...
(Dy2O3) holmium oxide is one of the most powerfully paramagnetic
Paramagnetism
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field. In contrast with this, diamagnetic materials are repulsive when placed in a magnetic field...
substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
called erbia. Typically the oxides of the trivalent lanthanide
Lanthanide
The lanthanide or lanthanoid series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium...
s coexist in nature and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
es. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the visible spectral range
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
. They are therefore traditionally used as a convenient calibration standard for optical spectrophotometers
Monochromator
A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input...
.
Appearance
Holmium oxide has some fairly dramatic color changes depending on the lighting conditions. In daylight, it is a tannish yellow color. Under trichromatic light, it is a fiery orange red, almost indistinguishable from the way erbium oxide looks under this same lighting. This is related to the sharp emission bands of the phosphors. Holmium oxide has a wide band gapBand gap
In solid state physics, a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference between the top of the valence band and the...
of 5.3 eV and thus should appear colorless. The yellow color originates from abundant lattice defects (such as oxygen vacancies) and is related to internal transitions at the Ho3+ ions.
Crystalline structure
Cubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
, yet rather complex structure, with many atoms per unit cell and a large lattice constant of 1.06 nm. This structure is characteristic of oxides of heavy rare-earth elements, such as Tb2O3, Dy2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3. The thermal expansion coefficient of Ho2O3 is also relatively large at 7.4 µm/°C.
Chemical
Treating holmium oxide with hydrogen chlorideHydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
or with ammonium chloride
Ammonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of ammonium chloride...
affords the corresponding holmium chloride
Holmium(III) chloride
Holmium chloride is the inorganic compound with the formula HoCl3. It is a common salt but is mainly used in research. It exhibits the same color-changing behavior seen in holmium oxide, being a yellow in natural lighting and a bright pink color in fluorescent lighting.-Preparation:It forms upon...
:
- Ho2O3 + 6 NH4Cl → 2 HoCl3 + 6 NH3 + 3 H2O
History
Holmium (Holmia, LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
name for Stockholm
Stockholm
Stockholm is the capital and the largest city of Sweden and constitutes the most populated urban area in Scandinavia. Stockholm is the most populous city in Sweden, with a population of 851,155 in the municipality , 1.37 million in the urban area , and around 2.1 million in the metropolitan area...
) was discovered by Marc Delafontaine
Marc Delafontaine
Marc Delafontaine was a Swiss chemist who in 1878, along with Jacques-Louis Soret, first observed holmium spectroscopically. In 1879, Per Teodor Cleve chemically separated it from thulium and erbium. The three are given credit for the element's discovery....
and Jacques-Louis Soret
Jacques-Louis Soret
Jacques-Louis Soret was a Swiss chemist who in 1878, along with Marc Delafontaine, first observed holmium spectroscopically. Independently, Per Teodor Cleve separated it chemically from thulium and erbium in 1879...
in 1878 who noticed the aberrant spectrographic
Spectrophotometry
In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength...
absorption band
Absorption band
An absorption band is a range of wavelengths, frequencies or energies in the electromagnetic spectrum which are able to excite a particular transition in a substance...
s of the then-unknown element (they called it "Element X"). Later in 1878, Per Teodor Cleve
Per Teodor Cleve
Per Teodor Cleve was a Swedish chemist and geologist.After graduating from the Stockholm Gymnasium in 1858, Cleve matriculated at Uppsala University in May 1858, where he received his PhD in 1863...
independently discovered the element while he was working on erbia earth (erbium oxide).
Using the method developed by Carl Gustaf Mosander
Carl Gustaf Mosander
Carl Gustaf Mosander was a Swedish chemist. He discovered the elements lanthanum, erbium and terbium....
, 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.
Occurrence
Gadolinite
Gadolinite, sometimes also known as Ytterbite, is a silicate mineral which consists principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula 2FeBe2Si2O10...
, monazite
Monazite
Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral:...
, and in other rare-earth mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s. Holmium metal readily oxidizes in air; therefore presence of holmium in nature is synonymous with that of holmia. With the abundance of 1.4 mg/kg, holmium is the 56th most abundant element. The main mining areas are China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
with reserves of holmium oxide estimated as 400,000 tonnes.
Production
A typical extraction process of holmium oxide can be simplified as follows: The mineral mixtures are crushed and ground. Monazite, because of its magnetic properties can be separated by repeated electromagnetic separation. After separation, it is treated with hot concentrated sulfuric acidSulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
to produce water-soluble sulfates of several rare earth elements. The acidic filtrates are partially neutralized with sodium hydroxide to pH 3-4. Thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
precipitates out of solution as hydroxide and is removed. After that, the solution is treated with ammonium oxalate
Ammonium oxalate
Ammonium oxalate, C2H8N2O4, is an oxalate salt with ammonia. It is a constituent of some types of kidney stone. Found also in guano....
to convert rare earths in to their insoluble oxalate
Oxalate
Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
s. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid
Nitric acid
Nitric 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 yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
that excludes one of the main components, cerium
Cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
, whose oxide is insoluble in HNO3.
The most efficient separation routine for holmium oxide from the rare-earths is ion exchange
Ion exchange
Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic 'ion...
. In this process, rare-earth ions are adsorbed 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, such as ammonium citrate or nitrilotracetate.
Applications
Cubic zirconia
Cubic zirconia is the cubic crystalline form of zirconium dioxide . The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate...
and glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, providing yellow or red coloring. Glass containing holmium oxide and holmium oxide solutions (usually in perchloric acid
Perchloric acid
Perchloric acid is the inorganic compound with the formula HClO4. Usually encountered as an aqueous solution, this colourless compound is a strong acid comparable in strength to sulfuric and nitric acids. It is a powerful oxidizer, but its aqueous solutions up to appr. 70% are remarkably inert,...
) have sharp optical absorption peaks in the spectral range 200-900 nm. They are therefore used as a calibration standard for optical spectrophotometers
Monochromator
A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input...
and are available commercially. As most other oxides of rare-earth elements, holmium oxide is used as a specialty catalyst, phosphor
Phosphor
A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness , and fluorescent materials, where the emission decay takes place over tens of nanoseconds...
and a laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
material. Holmium laser operates at wavelength of about 2.08 micrometres, either in pulsed or continuous regime. This laser is eye safe and is used in medicine, LIDAR
LIDAR
LIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...
s, wind velocity measurements and atmosphere monitoring.
Health effects
Holmium(III) oxide is, compared to many other compounds, not very dangerous, although repeated overexposure can cause granulomaGranuloma
Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
and hemoglobinemia
Hemoglobinemia
Hemoglobinemia is a medical condition in which there is an excess of hemoglobin in the blood plasma. This is an effect of intravascular hemolysis, in which hemoglobin separates from red blood cells, a form of anemia. Hemoglobinemia can be caused by intrinisic or extrinsic factors...
. It has low oral, dermal and inhalation toxicities and is non-irritating. The acute oral median lethal dose (LD50) is greater than 1 g per kilogram of body weight.