Holmium
Holmium is a soft, silvery lanthanide identified in the late 1870s and named after Holmia, the old Latin name for Stockholm. It holds the record for the strongest magnetic pull of any naturally occurring element, a property put to use in both research magnets and surgical lasers.
- Group · Period
- — · 6
- At room temp
- solid
- Melts at
- 1747 K
- Density
- 8.8 g/cm³
- Discovered
- 1878
Uses
Holmium’s claim to fame is having the highest magnetic moment of any naturally occurring element, meaning individual holmium atoms respond to magnetic fields more strongly than those of any other element. Researchers exploit this by using holmium in “flux concentrator” tips that help generate the most intense magnetic fields achievable in a laboratory. In medicine, holmium is the active ingredient in Ho:YAG lasers, which are widely used by urologists to break up kidney stones and by surgeons for certain other soft-tissue procedures, since the laser’s wavelength is strongly absorbed by water in tissue.
Holmium oxide is also valued in a much less dramatic but very practical role: dissolved in glass or solution, it produces a series of extremely sharp, well-defined absorption peaks, which makes it a reliable calibration standard for checking that spectrophotometers and other optical lab instruments are measuring wavelengths accurately.
History
Holmium was first detected spectroscopically in 1878 by researchers examining rare-earth mineral samples, and it was isolated as a distinct substance around the same time by Swedish chemist Per Teodor Cleve, working independently. Like other lanthanides pulled out of complex mineral mixtures in this era, its discovery involved more than one research group working in parallel, and its exact story is intertwined with the broader effort to sort out the rare earths. Cleve named the new element holmium after Holmia, the Latin name for Stockholm.
Fun facts
- Holmium has the highest magnetic moment of any naturally occurring element, making it useful for generating some of the strongest artificial magnetic fields ever produced.
- Holmium lasers are used by surgeons to break up kidney stones, a technique now common in urology.
- Glass colored with holmium oxide produces very sharp, well-defined absorption lines and is used as a calibration standard for scientific instruments.
Frequently asked questions
What is holmium used for?
Its strong magnetic properties make it useful in specialized magnets, including as a component in the tips of the most powerful electromagnets scientists build. In medicine, holmium is used in solid-state lasers — Ho:YAG lasers — that surgeons use to break apart kidney stones and to treat certain other conditions. Holmium oxide glass is also used as a stable, precise calibration standard for lab instruments that measure light wavelengths.
Why does holmium have such a strong magnetic pull?
Holmium atoms have a large number of unpaired electrons in a particular inner electron shell, which gives each atom an unusually strong individual magnetic moment. That's what makes holmium so useful when researchers want to concentrate magnetic fields to their highest achievable strength.
Who discovered holmium and how did it get its name?
It was identified spectroscopically in 1878 by researchers studying rare-earth samples, and isolated independently around the same time by Swedish chemist Per Teodor Cleve. Cleve named it after Holmia, the Latin name for Stockholm, his home city — continuing the common 19th-century practice of naming new rare earths after the places connected to their discovery.
Compounds
2 notable compounds containing Ho
- HoCl3halide
Holmium(III) chloride
A bright yellow, hygroscopic holmium salt typically handled as its hydrate, used as a common laboratory starting material for other holmium compounds.
Used for: Precursor for holmium metal and holmium-doped laser crystals
- Ho2O3oxide
Holmium(III) oxide
A pale yellow rare-earth oxide known for its extremely sharp optical absorption bands, which make holmium-doped glass a standard reference for calibrating spectrophotometers.
Used for: Wavelength calibration standard in optical spectroscopy instruments
Isotopes
39 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Ho-165 stable | 100% | Stable | — | -64,898.02 keV | 8,146.96 keV | — |
Show all 39 isotopes
| Ho-140 | — | 6 ms | Proton emission (100%) | -29,317 keV | 7,906 keV | 7.60 × 10-14 eV |
| Ho-141 | — | 4.1 ms | Proton emission (100%) | -34,364 keV | 7,943 keV | 1.11 × 10-13 eV |
| Ho-142 | — | 0.4 s | Electron capture / beta-plus decay (100%), ECP (0%), Proton emission (0%) | -37,250 keV | 7,965 keV | 1.14 × 10-15 eV |
| Ho-143 | — | — | Electron capture / beta-plus decay, ECP | -42,048 keV | 7,999 keV | — |
| Ho-144 | — | 0.7 s | Electron capture / beta-plus decay (100%), ECP | -44,609.52 keV | 8,017.1 keV | 6.52 × 10-16 eV |
| Ho-145 | — | 2.4 s | Electron capture / beta-plus decay (100%) | -49,120.11 keV | 8,048.58 keV | 1.90 × 10-16 eV |
| Ho-146 | — | 3.32 s | Electron capture / beta-plus decay (100%), ECP | -51,238.23 keV | 8,063.24 keV | 1.37 × 10-16 eV |
| Ho-147 | — | 5.8 s | Electron capture / beta-plus decay (100%) | -55,757.1 keV | 8,094.04 keV | 7.87 × 10-17 eV |
| Ho-148 | — | 2.2 s | Electron capture / beta-plus decay (100%) | -57,991.17 keV | 8,108.98 keV | 2.07 × 10-16 eV |
| Ho-149 | — | 21.0 s | Electron capture / beta-plus decay (100%) | -61,645.85 keV | 8,133.26 keV | 2.17 × 10-17 eV |
| Ho-150 | — | 72 s | Electron capture / beta-plus decay (100%) | -61,945.89 keV | 8,134.84 keV | 6.34 × 10-18 eV |
| Ho-151 | — | 35.2 s | Electron capture / beta-plus decay (78%), Alpha decay (22%) | -63,622.75 keV | 8,145.53 keV | 1.30 × 10-17 eV |
| Ho-152 | — | 161.8 s | Electron capture / beta-plus decay (88%), Alpha decay (12%) | -63,604.64 keV | 8,144.92 keV | 2.82 × 10-18 eV |
| Ho-153 | — | 2.01 m | Electron capture / beta-plus decay (99.949%), Alpha decay (0.051%) | -65,012.07 keV | 8,153.64 keV | 3.78 × 10-18 eV |
| Ho-154 | — | 11.76 m | Electron capture / beta-plus decay (99.981%), Alpha decay (0.019%) | -64,639.38 keV | 8,150.68 keV | 6.47 × 10-19 eV |
| Ho-155 | — | 48 m | Electron capture / beta-plus decay (100%) | -66,039.8 keV | 8,159.21 keV | 1.58 × 10-19 eV |
| Ho-156 | — | 56 m | Electron capture / beta-plus decay (100%) | -65,538.4 keV | 8,155.43 keV | 1.36 × 10-19 eV |
| Ho-157 | — | 12.6 m | Electron capture / beta-plus decay (100%) | -66,832.86 keV | 8,163.14 keV | 6.03 × 10-19 eV |
| Ho-158 | — | 11.3 m | Electron capture / beta-plus decay (100%) | -66,187.4 keV | 8,158.47 keV | 6.73 × 10-19 eV |
| Ho-159 | — | 33.05 m | Electron capture / beta-plus decay (100%) | -67,329.62 keV | 8,165.11 keV | 2.30 × 10-19 eV |
| Ho-160 | — | 25.6 m | Electron capture / beta-plus decay (100%) | -66,382.43 keV | 8,158.6 keV | 2.97 × 10-19 eV |
| Ho-161 | — | 2.48 h | Electron capture (100%) | -67,196.29 keV | 8,163.11 keV | 5.11 × 10-20 eV |
| Ho-162 | — | 15.0 m | Electron capture / beta-plus decay (100%) | -66,040.56 keV | 8,155.41 keV | 5.07 × 10-19 eV |
| Ho-163 | — | 4570 Y | Electron capture (100%) | -66,378.03 keV | 8,156.97 keV | 3.16 × 10-27 eV |
| Ho-164 | — | 28.8 m | Electron capture / beta-plus decay (60%), Beta-minus decay (40%) | -64,980.52 keV | 8,147.92 keV | 2.64 × 10-19 eV |
| Ho-166 | — | 26.824 h | Beta-minus decay (100%) | -63,070.34 keV | 8,135.49 keV | 4.72 × 10-21 eV |
| Ho-167 | — | 3.1 h | Beta-minus decay (100%) | -62,279.46 keV | 8,130.37 keV | 4.09 × 10-20 eV |
| Ho-168 | — | 2.99 m | Beta-minus decay (100%) | -60,059.23 keV | 8,116.81 keV | 2.54 × 10-18 eV |
| Ho-169 | — | 4.72 m | Beta-minus decay (100%) | -58,796.01 keV | 8,109.06 keV | 1.61 × 10-18 eV |
| Ho-170 | — | 2.76 m | Beta-minus decay (100%) | -56,237.51 keV | 8,093.79 keV | 2.76 × 10-18 eV |
| Ho-171 | — | 53 s | Beta-minus decay (100%) | -54,517.82 keV | 8,083.6 keV | 8.61 × 10-18 eV |
| Ho-172 | — | 25 s | Beta-minus decay (100%) | -51,484 keV | 8,066 keV | 1.82 × 10-17 eV |
| Ho-173 | — | 6.9 s | Beta-minus decay (100%) | -49,351 keV | 8,054 keV | 6.61 × 10-17 eV |
| Ho-174 | — | 3.2 s | Beta-minus decay (100%), Beta-minus, neutron emission | -45,870 keV | 8,034 keV | 1.43 × 10-16 eV |
| Ho-175 | — | 1.9 s | Beta-minus decay (100%), Beta-minus, neutron emission | -43,300 keV | 8,019 keV | 2.40 × 10-16 eV |
| Ho-176 | — | 160 ns | Beta-minus, neutron emission, Beta-minus decay | -39,390 keV | 7,997 keV | 2.85 × 10-9 eV |
| Ho-177 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | -36,280 keV | 7,980 keV | — |
| Ho-178 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | -32,130 keV | 7,957 keV | — |