Holmium has the highest magnetic strength of any element in the periodic table. Though it is not ferromagnetic at room temperature, like iron, cobalt and nickel, it becomes magnetic in the presence of a magnetic field. … Holmium can be used in lasers in combination with yttrium aluminum garnet (YAG).
Ho2O3, left: natural light, right: under a cold-cathode fluorescent lamp
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 has a tannish yellow color. Under trichromatic light, it is fiery orange-red, almost indistinguishable from the appearance of erbium oxide under the same lighting conditions. The perceived color change is related to the sharp absorption bands of holmium interacting with a subset of the sharp emission bands of the trivalent ions of europium and terbium, acting as phosphors.
Holmium has the highest magnetic moment
B) of any naturally occurring element and possesses other unusual magnetic properties. When combined with yttrium, it forms highly magnetic compounds. Holmium is paramagnetic at ambient conditions, but is ferromagnetic at temperatures below 19 K.
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 is generally trivalent. It 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:
2 Ho (s) + 3 H2SO4 (aq) → 2 Ho3+
(aq) + 3 SO2−
4 (aq) + 3 H2 (g)
Holmium’s most common oxidation state is +3. Holmium in solution is in the form of Ho3+ surrounded by nine molecules of water. Holmium dissolves in acids.
Main article: Isotopes of holmium
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.