Ho[1], is a metal element, chemical symbol Ho, atomic number 67,Atomic weight164.9，elementThe first name comes from the birthplace of the discoverer.Holmium melting point 1474 ℃, boiling point 2600 ℃, relative density 8.79g/cm ³.Holmium has a hexagonal close packed crystal structure at room temperature;There is ferromagnetism below - 253 ℃.[3]
Holmium is a soft rare earth metal with good ductility. It is relatively stable in dry air at room temperature, but can be rapidly oxidized in humid air or at higher temperatures.Holmium metal has unusual magnetismMonazite、SilybylliteHolmium is contained in other minerals.[4]
Holmium laser has excellent cutting ability and is widely used in the medical field.Holmium laser is commonly used in clinicstoneThe fragmentation of ureteral calculi includes the fragmentation of hard renal calculi and ureteral calculi.Holmium laser generates less heat, so it will not generate too much heat during use, which can reduce the thermal damage to human health tissues.[6]
Swedish chemist in 1842Mossandel(Mosander) After separating erbium earth and terbium earth from yttrium earth, many chemists used spectral analysis to identify that they were not pure oxides of an element, which encouraged chemists to continue to separate them.[5]
In 1878, J.L. Soret discovered holmium from the spectrum of erbium earth.[3]
In 1879, Swedish chemist Per Teodor Cleve separated Holmium from erbium oxide mineral and determined it.Cliff named the element after the Latin name "Holmia" in his birthplace, Stockholm.[7]
In 1886, Bowabodeland separated another element from Holmium, but the name of Holmium was retained.[5]
Physical and chemical properties
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physical property
Holmium is a silver white metal, soft and ductile, with a relative atomic mass of 164.9, a melting point of 1461 ℃, a boiling point of 2600 ℃, and a relative density of 8.79g/cm ³.Holmium has a hexagonal close packed crystal structure at room temperature;There is ferromagnetism below - 253 ℃.[3][6]
Physical properties of holmium
Relative atomic mass
one hundred and sixty-four point nine
density
8.79g/cm³
melting point
1461℃
boiling point
2600℃
Element Category
Rare earth, lanthanide
nature
Silver white metal under normal temperature
chemical property
Reaction of Holmium with Air
Holmium metal will slowly lose its luster in the air.Holmium can burn rapidly in the air to formHolmium oxide（Ⅲ）（Ho₂O₃）。[4]
Reaction of Holmium with Water
The silver white metal holmium has a very low electronegativity. It can react with cold water and quickly react with hot water to generate holmium hydroxide and hydrogen.[4]
Reaction of Holmium with Halogen
Holmium metal can react with all halogen elements to form trihalides.Metal holmium can be used withFluorine gas(F ₂), chlorine (Cl ₂), bromine (Br ₂), iodine (I ₂) react to produce holmium fluoride (Ⅲ) (HoF ∨), holmium chloride (Ⅲ) (HoCl ∨), holmium bromide (Ⅲ) (HoBr ∨), and holmium iodide (Ⅲ) (HoI ∨).[4]
Reaction of Holmium with Acid
Holmium metal can be rapidly dissolved insulphuric acidGreen solution containing hydrated Ho (Ⅲ) ion and hydrogen (H ₂) are generated.Ho ³+(aq) is most likely toCoordination ionHo (H ₂ O) ³+exists in the form of.[4]
Preparation method
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holmium
It is difficult to separate holmium from other elements and obtain pure metal holmium, which largely depends on its existence in nature.There are many kinds of rare earth minerals in nature, among whichXenotime、MonaziteandBastnasiteMost importantly, the first two minerals are orthophosphate LnPO (Ln means that except for very rarePromethiumExcept all lanthanide elements), while bastnasite is a double salt ore LnCO ≮ F in the form of fluoride and carbonate.Lanthanide elements with even atomic numbers are common.The most common lanthanide elements in the above minerals are mainly cerium, lanthanum, neodymium andpraseodymium。Monazite also contains thorium（Actinide element）And yttrium.Thorium and its decay products are radioactive, which makes them more difficult to deal with.[4]
In many cases, it is not necessary to separate all kinds of metals, but if it is necessary to do so, the process will be very complicated.Use sulfuric acid (H ₂ SO ₄)hydrochloric acid(HCl) andsodium hydroxide(NaOH) leaches out rare earth metals in the form of salt.When separating and purifying these salts, the commonly used methods now include selective coordination technology, extraction technology and ion exchange resin.[4]
Pure holmium can be obtained by reducing HoF ∨ with metallic calcium.[4]
Other holmium halides can also be used for this reaction, but under the selected reaction conditions (heated in argon to 50 ℃ higher than the metal melting point), the calcium fluoride generated will be easier to treat than other calcium halides.Excess calcium can be removed from the reaction mixture under vacuum conditions.[4]
application area
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Industrial use
Holmium compounds can be used as new magnetic materialsYttrium iron garnetandYttrium aluminum garnetAdditives.Holmium iodide is used to make metal halide lamps - holmium lamps.[3]
Holmium doped fiber can be used to make fiber laser, fiber amplifier, fiber sensor and other optical communication devices.[5]
Medical use
Holmium laser lithotripsy technology
Medical holmium laser lithotripsy is applicable to hard kidney stones, ureteral stones and bladder stones that cannot be broken by extracorporeal shock wave lithotripsy.When medical holmium laser lithotripsy is performed, the thin optical fiber of medical holmium laser passes through the urethra and ureter to bladder stones, ureteral stones and kidney stones with the help of cystoscope and ureteroscope, and then the urologist manipulates the holmium laser to break the stones.The advantage of this treatment method is that it can solve ureteral stones, bladder stones and most kidney stones.The disadvantage is that for some stones in the upper and lower renal calices, a small amount of stones will remain because the Holmium laser optical fiber entering from the ureter cannot reach the stone site.[5]
Distribution
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The content of Holmium in the crust is 1.15x10 ⁻ ≮%, which israre earth elementOne of the least abundant elements in.Titanium exists with other rare earth elementsMonaziteAnd manyRare earth oreThe content in monazite is about 0.05%, and titanium also exists in nuclear fission products (see fission chemistry).The stable isotope of Holmium in nature is Holmium 165.[3]
In addition, Holmium also exists in trace amounts in silybyllite, xenotime, black rare gold ore, limonite and bastnasite.Among them, monazite ores are mainly distributed in China, Australia, India, Brazil, Congo, South Africa, the United States and Russia, silybyllium yttrium ores are mainly distributed in Sweden, Norway, the United States, phosphoyttrium ores are mainly distributed in China, Australia, Norway and Brazil, and black rare gold ores are mainly distributed in Australia and the United States.
Safety measures
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Although previous evidence suggests that the toxicity of holmium seems to be limited, in fact all compounds of holmium are highly toxic.The powder of holmium metal may cause fire and explosion.[4]
Toxicological data
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Cytotoxicity
Holmium oxide
Holmium nitrateIts toxicity is easily detected at the cellular and subcellular levels.Studies have shown that when the concentration is higher than 4 mg/lHolmium nitrateTreatment of Vicia faba root tip can cause the root tip texture to harden, color to darken, growth to slow down, cell division index to decline and other phenomena, and with the increase of dose or the extension of exposure time, the degree of damage to root tip cells tends to increase.Similar results have also appeared in the animal's in vivo test. In addition, it can also be observed under the microscopelymphocyteAbnormal phenomena such as nuclear condensation, hyperchromatism, fragmentation, chromatin margination, exocytosis, and invagination, and the degree and proportion of nuclear abnormalities show an upward trend with the increase of dose.All these indicate that holmium nitrate has a certain toxic effect on cells.[5]
Qu AiThey used micronucleus technology to study Vicia faba root tip cells treated with Holmium nitrate, and found that with the increasing concentration of Holmium nitrate, the micronucleus rate and chromosome aberration rate gradually increased, and there was an obvious dose effect relationship, indicating that Holmium had certain genotoxicity.Similar results were obtained in the study of mice. Holmium nitrate caused chromosome damage to some extent.It can be seen that holmium and its compounds can indeed induce aberrations at the chromosome level, playing the role of chromosome poison.[5]
Holmium ion can induce DNA breakage in Vicia faba root tip cells, and has obvious toxic effect on DNA. The degree of damage is related to the treatment dose and time.[5]
Biotoxicity
Animal experiments show that holmium nitrate can improveSuperoxide dismutase（SOD）、Peroxidase（POD）、catalase(CAT) activity, which can remove excesssuperoxide anion Free radicals (OF) and inhibition of lipid peroxidation.Low dose of holmium can reduce the oxidative damage of free radicals to biological macromolecules and cells, but high dose of holmium can reduce the activity of antioxidant enzymes, so that free radicals accumulate in the body, destroy the structure and function of cells, and lead to mutation, indicating that holmium has a certain mutagenic effect at high dose.[5]
Storage and transportation
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Holmium laser drilling
Store in a cool and ventilated warehouse.Keep away from kindling and heat sources.It shall be stored separately from oxidants, acids, halogens, etc., and mixed storage is strictly prohibited.Explosion proof lighting and ventilation facilities shall be adopted.It is prohibited to use mechanical equipment and tools that are easy to generate sparks.The storage area shall be equipped with appropriate materials to contain leakage.
