Neodymium(III) chloride
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Names | |||
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Other names
Neodymium trichloride
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Identifiers | |||
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3D model (
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ChemSpider | |||
ECHA InfoCard
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100.030.016 | ||
PubChem CID
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UNII | |||
CompTox Dashboard (EPA)
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Properties | |||
NdCl3, NdCl3·6H2O (hydrate) | |||
Molar mass | 250.598 g/mol | ||
Appearance | Mauve-colored powder hygroscopic
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Density | 4.13 g/cm3 (2.3 for hydrate)[1] | ||
Melting point | 759 °C (1,398 °F; 1,032 K)[1] | ||
Boiling point | 1,600 °C (2,910 °F; 1,870 K)[1] | ||
1 kg/L at 25 °C[1] | |||
Solubility in ethanol | 0.445 kg/L | ||
Structure[2] | |||
UCl3 type), hP8
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P63/m, No. 176 | |||
a = 0.73988 nm, c = 0.42423 nm
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Formula units (Z)
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2 | ||
Tricapped trigonal prismatic (nine-coordinate) | |||
Hazards | |||
GHS labelling: | |||
Warning | |||
H315, H319, H335 | |||
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |||
NFPA 704 (fire diamond) | |||
Safety data sheet (SDS) | External SDS | ||
Related compounds | |||
Other anions
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Neodymium(III) bromide Neodymium(III) oxide | ||
Other cations
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LaCl3, SmCl3, PrCl3, EuCl3, CeCl3, GdCl3, TbCl3, Promethium(III) chloride | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Neodymium(III) chloride or neodymium trichloride is a chemical compound of
Appearance
NdCl3 is a mauve colored
Structure
Solid
The anhydrous NdCl3 features Nd in a nine-coordinate tricapped trigonal prismatic geometry and crystallizes with the
Solution
The structure of neodymium(III) chloride in solution crucially depends on the solvent: In water, the major species are Nd(H2O)83+, and this situation is common for most rare earth chlorides and bromides. In methanol, the species are NdCl2(CH3OH)6+ and in hydrochloric acid NdCl(H2O)72+. The coordination of neodymium is octahedral (8-fold) in all cases, but the ligand structure is different.[5]
Properties
NdCl3 is a soft
- 2 NdCl3 + Nd → 3 NdCl2
Heating of NdCl3 with water vapors or
- NdCl3 + H2O → NdOCl + 2 HCl
- 2 NdCl3 + SiO2 → 2 NdOCl + SiCl4
Reacting NdCl3 with
- 2 NdCl3 + 3 H2S → 2 Nd2S3 + 6 HCl
Reactions with
- NdCl3 + NH3 → NdN + 3 HCl
- NdCl3 + PH3 → NdP + 3 HCl
Whereas the addition of
- NdCl3 + 3 HF → NdF3 + 3 HCl
Preparation
NdCl3 is produced from minerals monazite and bastnäsite. The synthesis is complex because of the low abundance of neodymium in the Earth's crust (38 mg/kg) and because of difficulty of separating neodymium from other lanthanides. The process is however easier for neodymium than for other lanthanides because of its relatively high content in the mineral – up to 16% by weight, which is the third highest after cerium and lanthanum.[10] Many synthesis varieties exist and one can be simplified as follows:
The crushed mineral is treated with hot concentrated sulfuric acid to produce water-soluble sulfates of rare earths. 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 into their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid that excludes the main components, cerium, whose oxide is insoluble in HNO3. Neodymium oxide is separated from other rare-earth oxides by ion exchange. In this process, rare-earth ions are adsorbed onto suitable resin by ion 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.[9]
This process normally yields Nd2O3; the oxide is difficult to directly convert to elemental neodymium, which is often the goal of the whole technological procedure. Therefore, the oxide is treated with hydrochloric acid and ammonium chloride to produce the less stable NdCl3:[9]
- Nd2O3 + 6 NH4Cl → 2 NdCl3 + 3 H2O + 6 NH3
The thus produced NdCl3 quickly absorbs water and converts to NdCl3·6H2O hydrate, which is stable for storage, and can be converted back into NdCl3 when necessary. Simple rapid heating of the hydrate is not practical for that purpose because it causes hydrolysis with consequent production of Nd2O3.[11] Therefore, anhydrous NdCl3 is prepared by dehydration of the hydrate either by slowly heating to 400 °C with 4-6 equivalents of ammonium chloride under high vacuum, or by heating with an excess of thionyl chloride for several hours.[4][12][13][14] The NdCl3 can alternatively be prepared by reacting neodymium metal with hydrogen chloride or chlorine, though this method is not economical due to the relatively high price of the metal and is used for research purposes only. After preparation, it is usually purified by high temperature sublimation under high vacuum.[4][15][16]
Applications
Production of neodymium metal
Neodymium(III) chloride is the most common starting compound for production of neodymium metal. NdCl3 is heated with ammonium chloride or ammonium fluoride and hydrofluoric acid or with alkali or alkaline earth metals in vacuum or argon atmosphere at 300–400 °C.
- 2 NdCl3 + 3 Ca → 2 Nd + 3 CaCl2
An alternative route is
Lasers and fiber amplifiers
Although NdCl3 itself does not have strong
Neodymium(III) chloride is a dopant not only of traditional silica-based optical fibers, but of plastic fibers (dopedphotolime-gelatin,
Solubility of neodymium(III) chloride (and other rare-earth salts) is various solvents results in a new type of rare-earth laser, which uses not a solid but liquid as an active medium. The liquid containing Nd3+ ions is prepared in the following reactions:
- SnCl4 + 2 SeOCl2 → SnCl62− + 2 SeOCl+
- SbCl5 + SeOCl2 → SbCl6− + SeOCl+
- 3 SeOCl+ + NdCl3 → Nd3+(solv) + 3 SeOCl2,
where Nd3+ is in fact the solvated ion with several selenium oxychloride molecules coordinated in the first coordination sphere, that is [Nd(SeOCl2)m]3+. The laser liquids prepared by this technique emits at the same wavelength of 1.064 micrometres and possess properties, such as high gain and sharpness of the emission, that are more characteristic of crystalline than Nd-glass lasers. The quantum efficiency of those liquid lasers was about 0.75 relative to the traditional Nd:YAG laser.[21]
Catalysis
Another important application of NdCl3 is in catalysis—in combination with organic chemicals, such as
Neodymium(III) chloride is also used to modify
Corrosion protection
Other applications are being developed. For example, it was reported that coating of aluminium or various aluminium alloys produces very corrosion-resistance surface, which then resisted immersion into concentrated aqueous solution of NaCl for two months without sign of pitting. The coating is produced either by immersion into aqueous solution of NdCl3 for a week or by electrolytic deposition using the same solution. In comparison with traditional chromium based corrosion inhibitors, NdCl3 and other rare-earth salts are environment friendly and much less toxic to humans and animals.[28][29]
The protective action of NdCl3 on aluminium alloys is based on formation of insoluble neodymium hydroxide. Being a chloride, NdCl3 itself is a corrosive agent, which is sometimes used for corrosion testing of ceramics.[30]
Labeling of organic molecules
Lanthanides, including neodymium are famous for their bright luminescence and therefore are widely used as fluorescent labels. In particular, NdCl3 has been incorporated into organic molecules, such as DNA, which could be then easily traced using a fluorescence microscope during various physical and chemical reactions.[21]
Health issues
Neodymium(III) chloride does not seem toxic to humans and animals (approximately similar to table salt). The LD50 (dose at which there is 50% mortality) for animals is about 3.7 g per kg of body weight (mouse, oral), 0.15 g/kg (rabbit, intravenous injection). Mild irritation of skin occurs upon exposure with 500 mg during 24 hrs (Draize test on rabbits).[31] Substances with LD50 above 2 g/kg are considered non-toxic.[32]
See also
- Lanthanoid
- Neodymium-doped yttrium lithium fluoride
References
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- ISBN 0-7506-5856-8.
- ^ a b c Edelmann, F. T.; Poremba, P. (1997). W. A. Herrmann (ed.). Synthetic Methods of Organometallic and Inorganic Chemistry Vol. 6. Stuttgart: Georg Thieme Verlag.
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- ^ ISBN 0-07-049439-8. Retrieved 2009-06-06.
- ISBN 0-19-850340-7.
- ^ ISBN 3-540-34809-3.
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- ^ Corbett, J. D. (1973). "Reduced Halides of the Rare Earth Elements". Rev. Chim. Minérale. 10: 239.
- ISBN 0-415-33340-7.
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- ISBN 0-444-81592-9.
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- ^ ISBN 978-0-444-52144-6.
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- ISBN 0-8031-1435-4.
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- ^ "Neodymium Chloride". American Elements. Retrieved 2009-07-07.
- ISBN 978-0-12-276060-0.