Holmium: Wikis

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dysprosiumholmiumerbium
-

Ho

Es
Appearance
silvery white
General properties
Name, symbol, number holmium, Ho, 67
Element category lanthanide
Group, period, block n/a6, f
Standard atomic weight 164.93032g·mol−1
Electron configuration [Xe] 4f11 6s2
Electrons per shell 2, 8, 18, 29, 8, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 8.79 g·cm−3
Liquid density at m.p. 8.34 g·cm−3
Melting point 1734 K, 1461 °C, 2662 °F
Boiling point 2993 K, 2720 °C, 4928 °F
Heat of fusion 17.0 kJ·mol−1
Heat of vaporization 265 kJ·mol−1
Specific heat capacity (25 °C) 27.15 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1432 1584 (1775) (2040) (2410) (2964)
Atomic properties
Oxidation states 3 (basic oxide)
Electronegativity 1.23 (Pauling scale)
Ionization energies 1st: 581.0 kJ·mol−1
2nd: 1140 kJ·mol−1
3rd: 2204 kJ·mol−1
Atomic radius 176 pm
Covalent radius 192±7 pm
Miscellanea
Crystal structure hexagonal
Magnetic ordering paramagnetic
Electrical resistivity (r.t.) (poly) 814 nΩ·m
Thermal conductivity (300 K) 16.2 W·m−1·K−1
Thermal expansion (r.t.) (poly) 11.2 µm/(m·K)
Speed of sound (thin rod) (20 °C) 2760 m/s
Young's modulus 64.8 GPa
Shear modulus 26.3 GPa
Bulk modulus 40.2 GPa
Poisson ratio 0.231
Vickers hardness 481 MPa
Brinell hardness 746 MPa
CAS registry number 7440-60-0
Most stable isotopes
Main article: Isotopes of holmium
iso NA half-life DM DE (MeV) DP
163Ho syn 4570 yr ε 0.003 163Dy
164Ho syn 29 min ε 0.987 164Dy
165Ho 100% 165Ho is stable with 98 neutrons
166Ho syn 26.763 h β 1.855 166Er
167Ho syn 3.1 h β 1.007 167Er

Holmium (pronounced /ˈhoʊlmiəm/, HOHL-mee-əm) is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite. Holmium has the highest magnetic strength of any element and therefore is used for the polepieces of the strongest static magnets. Because holmium can absorb nuclear fission-bred neutrons, it is also used in nuclear control rods and for components for electronic devices.

Contents

Characteristics

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Physical

Ho2O3, left: natural light, right: fluorescent lamp light

Holmium is a relatively soft and malleable element that is fairly corrosion-resistant and stable in dry air at standard temperature and pressure. 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 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.[1]

A trivalent metallic rare earth element, holmium has the highest magnetic moment (10.6 µB) of any naturally-occurring element and possesses other unusual magnetic properties. When combined with yttrium, it forms highly magnetic compounds.[2] Holmium is paramagnetic at ambient conditions, but is ferromagnetic at temperatures below 19 K.[3]

Chemical

Holmium metal tarnishes slowly in air and burns readily to form holmium(III) oxide:

4 Ho + 3 O2 → 2 Ho2O3

Holmium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form holmium hydroxide:

2 Ho (s) + 6 H2O (l) → 2 Ho(OH)3 (aq) + 3 H2 (g)

Holmium metal reacts with all the halogens:

2 Ho (s) + 3 F2 (g) → 2 HoF3 (s) [pink]
2 Ho (s) + 3 Cl2 (g) → 2 HoCl3 (s) [yellow]
2 Ho (s) + 3 Br2 (g) → 2 HoBr3 (s) [yellow]
2 Ho (s) + 3 I2 (g) → 2 HoI3 (s) [yellow]

Holmium dissolves readily in dilute sulfuric acid to form solutions containing the yellow Ho(III) ions, which exist as a [Ho(OH2)9]3+ complexes:[4]

2 Ho (s) + 3 H2SO4 (aq) → 2 Ho3+ (aq) + 3 SO 2−4 (aq) + 3 H2 (g)

Isotopes

Natural holmium contains one stable isotope, holmium-165. Some synthetic radioactive isotopes are known, the most stable one is holmium-163, with a half life of 4570 years. All other radioisotopes have ground-state half lives not greater than 1.117 days, and most have half lives under 3 hours. However, the metastable 166m1Ho has a half life of around 1200 years because of its high spin. This fact, combined with a high excitation energy resulting in a particularly rich spectrum of decay gamma rays produced when the metastable state de-excites, makes this isotope useful in nuclear physics experiments as a means for calibrating energy responses and intrinsic efficiencies of gamma ray spectrometers.

History

Holmium (Holmia, Latin name for Stockholm) was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878 who noticed the aberrant spectrographic absorption bands of the then-unknown element (they called it "Element X").[5][6] Later in 1878, Per Teodor Cleve independently discovered the element while he was working on erbia earth (erbium oxide).[7][8]

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.[9]

Occurrence and production

Gadolinite

Like all other rare earths, holmium is not naturally found as a free element. It does occur combined with other elements in the minerals gadolinite, monazite, and in other rare-earth minerals. The main mining areas are China, United States, Brazil, India, Sri Lanka and Australia with reserves of holmium estimated as 400,000 tonnes.[9]

It is commercially extracted via ion-exchange 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 chloride or fluoride with metallic calcium.[10] 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 its immediate even-numbered neighbors, dysprosium and erbium. However, it is the most abundant of the odd-numbered heavy lanthanides. 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 weight; holmium is around 1.5%. The original ores themselves are very lean, maybe only 0.1% total lanthanide, but are easily extracted.[11] Holmium is relatively inexpensive for a rare-earth metal with the price about US$ 1000 per kg.[12]

Applications

A solution of 4% holmium oxide in 10% perchloric acid, permanently fused into a quartz cuvette as an optical calibration standard

Holmium has the highest magnetic strength of any element, and therefore is used to create the strongest artificially-generated magnetic fields, when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator). Since it can absorb nuclear fission-bred neutrons, it is also used in nuclear control rods.[9]

Holmium is used in yttrium-iron-garnet (YIG)- and yttrium-lanthanum-fluoride (YLF) solid-state lasers found in microwave equipment (which are in turn found in a variety of medical and dental settings). Holmium lasers emit at 2.08 microns, and therefore are safe to eyes. They are used in medical, dental, and fiber-optical applications.[2]

Holmium is one of the colorants used for cubic zirconia and glass, providing yellow or red coloring.[13] 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[14], and are available commercially.[15]

The radioactive but long-lived Ho-166m1 (see "Isotopes" above) is used in calibration of gamma ray spectrometers.[16]

Precautions

The element, as with other rare earths, appears to have a low degree of acute toxicity. Holmium plays no biological role in humans, but may be able to stimulate metabolism.[10]

See also

References

  1. ^ Su, Yiguo; Li, Guangshe; Chen, Xiaobo; Liu, Junjie; Li, Liping (2008). "Hydrothermal Synthesis of GdVO4:Ho3+ Nanorods with a Novel White-light Emission". Chemistry Letters 37: 762. doi:10.1246/cl.2008.762.  
  2. ^ a b C. K. Gupta, Nagaiyar Krishnamurthy (2004). Extractive metallurgy of rare earths. CRC Press. p. 32. ISBN 0415333407. http://books.google.co.jp/books?id=F0Bte_XhzoAC&pg=PA32.  
  3. ^ Jiles, David (1998). Introduction to magnetism and magnetic materials. CRC Press. p. 228. ISBN 0412798603. http://books.google.com/books?id=axyWXjsdorMC&pg=PA228.  
  4. ^ "Chemical reactions of Holmium". Webelements. https://www.webelements.com/holmium/chemistry.html. Retrieved 2009-06-06.  
  5. ^ Jacques-Louis Soret (1878). "Sur les spectres d'absorption ultra-violets des terres de la gadolinite". Comptes rendus de l'Académie des sciences 87: 1062. http://gallica.bnf.fr/ark:/12148/bpt6k3043m/f1124.table.  
  6. ^ Jacques-Louis Soret (1879). "Sur le spectre des terres faisant partie du groupe de l'yttria". Comptes rendus de l'Académie des sciences 89: 521. http://gallica.bnf.fr/ark:/12148/bpt6k3046j/f550.table.  
  7. ^ Per Teodor Cleve (1879). "Sur deux nouveaux éléments dans l'erbine". Comptes rendus de l'Académie des sciences 89: 478. http://gallica.bnf.fr/ark:/12148/bpt6k3046j/f432.table.  
  8. ^ Per Teodor Cleve (1879). "Sur l'erbine". Comptes rendus de l'Académie des sciences 89: 708. http://gallica.bnf.fr/ark:/12148/bpt6k3046j/f759.table.  
  9. ^ a b c John Emsley (2001). Nature's building blocks: an A-Z guide to the elements. US: Oxford University Press. pp. 181–182. ISBN 0198503415. http://books.google.com/books?id=Yhi5X7OwuGkC&pg=PA181.  
  10. ^ a b C. R. Hammond (2000). The Elements, in Handbook of Chemistry and Physics 81th edition. CRC press. ISBN 0849304814.  
  11. ^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. pp. 338–339. ISBN 0070494398. http://books.google.com/books?id=Xqj-TTzkvTEC&pg=PA338. Retrieved 2009-06-06.  
  12. ^ James B. Hedrick. "Rare-Earth Metals". USGS. http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/740798.pdf. Retrieved 2009-06-06.  
  13. ^ "Cubic zirconia". http://www.geologyrocks.co.uk/tutorials/cubic_zirconia. Retrieved 2009-06-06.  
  14. ^ R. P. MacDonald (1964). "Uses for a Holmium Oxide Filter in Spectrophotometry". Clinical Chemistry 10: 1117. http://www.clinchem.org/cgi/reprint/10/12/1117.pdf.  
  15. ^ "Holmium Glass Filter for Spectrophotometer Calibration". http://www.labshoponline.com/holmium-glass-filter-spectrophotometer-calibration-p-88.html. Retrieved 2009-06-06.  
  16. ^ Ming-Chen Yuan, Jeng-Hung Lee and Wen-Song Hwang (2002). "The absolute counting of 166mHo, 58Co and 88Y". Applied Radiation and Isotopes 56: 424. doi:10.1016/S0969-8043(01)00226-3.  
  • Guide to the Elements – Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also holmium

German

Chemical Element: Ho (atomic number 67)

Noun

Holmium n

  1. holmium

Simple English

Holmium (pronounced /ˈhoʊlmiəm/) is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite.

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