Rare earth element | Holmium (Ho)

In the second half of the 19th century, the discovery of spectroscopic analysis and the publication of periodic tables, coupled with the advancement of electrochemical separation processes for rare earth elements, further promoted the discovery of new rare earth elements. In 1879, Cliff, a Swede, discovered the element of holmium and named it holmium after the place name of Stockholm, the capital of Sweden.

The application field of holmium still needs further development, and the dosage is not very large. Recently, Baotou Steel Rare Earth Research Institute has adopted high-temperature and high vacuum distillation purification technology to develop a high-purity metal holmium with very low content of non rare earth impurities/ Σ RE>99.9％。 At present, the main uses of holmium are as follows.

(1) As an additive for metal halide lamps, metal halide lamps are a type of gas discharge lamp developed on the basis of high-pressure mercury lamps, characterized by filling the bulb with various rare earth halides. At present, the main use is rare earth iodide, which emits different spectral colors during gas discharge. The working substance used in holmium lamps is holmium iodide, which can achieve a high concentration of metal atoms in the arc zone, greatly improving radiation efficiency.

(2) Holmium can be used as an additive for yttrium iron or yttrium aluminum garnet.

(3) Ho: YAG doped yttrium aluminum garnet can emit 2 μ M laser, the absorption rate of human tissue to 2um laser is high, almost three orders of magnitude higher than that of Hd: YAG. So when using Ho: YAG laser for medical surgery, not only can the surgical efficiency and accuracy be improved, but also the thermal damage area can be reduced to a smaller size. The free beam generated by holmium crystals can eliminate fat without generating excessive heat, thereby reducing thermal damage to healthy tissues. It is reported that holmium laser treatment for glaucoma in the United States can reduce the pain of patients undergoing surgery. China 2 μ The level of m laser crystals has reached international level, and efforts should be made to develop and produce this type of laser crystal.

(4) In the magnetostrictive alloy Terfenol D, a small amount of holmium can also be added to reduce the external field required for saturation magnetization of the alloy.

(5) In addition, holmium doped fibers can be used to make optical communication devices such as fiber lasers, fiber amplifiers, and fiber sensors, which will play a more important role in the rapid development of fiber communication today.