What magical applications do rare earth elements have? (Ⅳ) ——About the application of heavy rare earth elements

9. Application of Terbium

Terbium element symbols Tb and its atomic weight is 158.9253

It can be used in tri-color phosphors. Whether the phosphor is about phosphate matrix, silicate matrix, or cerium magnesium aluminate matrix, doping with terbium can stimulate high-quality green.

When it comes to work as ‘magneto-optical storage material’, now it has reached the scale of mass production, using Tb-Fe amorphous film as a magneto-optical disc and computer storage element. The storage capacity is increased by 10 to 15 times.

‘Magnetostrictive alloy’ added terbium is a new material discovered in the 1970s. Half of the alloy is terbium and dysprosium, in which sometimes holmium is added, and of which the rest is iron. With the change of magnetic field strength, the size of the material changes greatly, so the material can be used in sonar (sound waves are emitted with magnetic field vibration), precision mechanical movement (using a magnetic field to control the distance of entry and exit), and can also be used for fuel injection control, liquid valve control, micro-positioning movement control, space telescope adjustment control, and aircraft wing adjustment control.

10. Application of Dysprosium

The element symbol of Dysprosium is Dy, and its atomic weight is 162.5.

It is used as an additive for permanent magnets. Adding about 2~3% of Dysprosium to NdFeB permanent magnets can further improve its coercivity. The demand for Dysprosium is increasing currently.

It is used for ‘three-color luminescent phosphors’.

It is also used for ‘magnetostrictive alloys’, ‘dysprosium and ferrite alloy materials’ and ‘ytterbium and ferrite alloy materials’ do have good magnetostriction.

As for ‘magneto-optical storage materials’, dysprosium has high recording speed and reading sensitivity.

‘Halogen’ lighting lamps made of Dysprosium iodide have the advantages of high brightness, good color rendering, high color temperature, small size, stable arc, etc., and have been used in lighting sources such as movies and printing. These are the samples for dysprosium used for lighting sources.

We also can see its participation in ‘neutron absorbers’ and ‘magnetic refrigeration materials’, ‘rare earth tri-color phosphors’, ‘rare earth magnetostrictive alloys’, ‘rare earth magnetic refrigeration materials’, and ‘rare earth magneto-optical storage materials’ .

11. Application of holmium

The element symbol of holmium is Ho and its atomic weight is 164.9.

It is used as an additive for halogen lamps. Halogen lamps are gas discharge lamps that can be filled with various rare earth halides. Currently, rare earth iodides are mainly used, which emit different spectral light colors during gas discharge. The working substance used in holmium lamps is holmium iodide, which has a stable arc zone and improved radiation efficiency.

Holmium can be used as an additive for yttrium iron or yttrium aluminum garnet. This crystal can emit 2μm laser and be used as a "laser scalpel" for human tissues, which improves surgical efficiency and accuracy and reduces the thermal damage area.

It is used for ‘magnetostrictive alloys’ and used to make optical fiber lasers, optical fiber amplifiers, optical fiber sensors, etc.

12. Application of Erbium

The element symbol of erbium is Er, and its atomic weight is 167.26

The chemical and physical properties of erbium are almost identical to those of holmium and dysprosium.

It can be used in ‘rare earth glass laser materials’, which is a solid laser materials. The laser pulses it outputs have two characteristics: one is the maximum energy, and the other is concentrated at 1550nm and 1730nm wavelengths.

When irradiated by 980nm or 1480nm laser,  will emit a laser with a wavelength of 1550nm, which has the least loss when propagating in the optical fiber. Based on this, this laser can be used to carry information in the optical fiber, and can also be used in optical signal enhancement devices during the propagation process. It can be said that the application of erbium has brought optical fiber communication to a higher level.

Lasers with wavelengths of 1550nm and 1730nm are safe for human eyes and have strong penetration ability for fog barriers. Therefore, they can be used in portable laser rangefinders, which are safe and reliable, not easy to detect.

Erbium solid laser can excite laser with a wavelength of 2940nm, which can cut human tissue accurately and efficiently, and has a good hemostasis effect.

Erbium oxide is rose red, can be mixed with glass or glazed, and presents bright pink after sintering.

13. Thulium

The single compound of thulium is Tm and its atomic weight is 168.9.

Thulium is mainly used as a new type of lighting source, an additive to metal halide lamps, and the light it emits is a broad spectrum of green.

Nowadays, thulium-doped lasers are gaining more and more attention. When excited,  can output strong pulsed lasers and can be made into solid lasers; the transmission performance of thulium-doped optical fibers is also particularly good; therefore, ‘laser generation’, "laser enhancement" and ‘laser transmission’ are organically combined to make small medical lasers with small incisions, fast cutting speeds, controllable cutting depths, and easy recovery from cuts.

Thulium isotopes can be used as local X-ray sources. Since thulium will produce isotopes that can emit X-rays after irradiation in a nuclear reactor, it can be used to make portable X-ray sources.

After irradiated with X-rays, thulium will excite weak radiation, and it is used as an ‘X-ray-related’ screen fluorescence enhancement activator.

Today, the use of thulium in tumor examination is also highly valued. Thulium can also be used in the clinical diagnosis and treatment of tumors. Among the rare earth elements, thulium has the greatest affinity for tumor tissue. If taking some thulium oxide and test it after some time, we can find the location and shape of the tumor.

14. Application of Ytterbium

The symbol of ytterbium is Yb, and its atomic weight is 173.04.

The spectral characteristics of ytterbium have been used as high-quality laser crystals, laser glass, fiber laser amplifiers, etc.

Although the rare earth element erbium is still the main element in the preparation of fiber amplifiers, the traditional erbium-doped quartz fiber has a small gain bandwidth, which is difficult to meet the requirements of high-speed and large-capacity information transmission.  ions have a large gain bandwidth near 980nm, and further exciting erbium and ytterbium can greatly enhance the 1530nm light, thereby greatly improving the light amplification efficiency.

Adding rare earth elements such as ytterbium and erbium to semiconductor laser (LD) materials can make a high-efficiency, high-energy ‘new pump source’ to further improve the transmission efficiency of fiber-optic communication. China has currently built the world's largest single-channel capacity and fastest optical transmission system and has the world's widest information highway. Ytterbium-doped and other rare-earth fiber amplification and laser materials have played a key role in this.

In recent years, erbium-ytterbium co-doped phosphate and fluorophosphate glass have been favored by more and more researchers. This type of glass has good chemical stability and thermal stability, high infrared transmittance, and wide transmission bandwidth. This type of material can be made into high-power lasers.

We have now made tunable laser crystals, garnets doped with chromium, ytterbium, holmium, yttrium, aluminum, and gallium, whose wavelength is continuously adjustable between 2.84 and 3.05μm. This tunable infrared laser has important military application value.

Rare earth materials are used in optical fibers and their optical transmission, optical fiber glass, high-power lasers, laser weapons, etc. We are in a leading position in the world in these technologies.

As for ytterbium, it can be used for "thermal insulation materials", "radiation shielding materials", "magnetostrictive materials", "phosphor activation materials", and "magnetostrictive storage materials", which will not be elaborated on here.

15. Application of Lutetium

Lutetium single compound is Lu and the atomic weight 175.0.

Lutetium usually coexists with yttrium and has the same general effect as heavy rare earth elements.

It can be used to make some special alloys, such as lutetium aluminum alloy, which can be used for neutron activation analysis.

It can be used as a catalyst. Lutetium yttrium is often used as a catalyst in petroleum cracking, alkylation, hydrogenation, and polymerization reactions.

The material that emits ‘a certain frequency laser’ by electricity is combined with the material that is activated to emit ‘another green light’, such as lutetium aluminum tetraborate yttrium neodymium. Directly energizing this composite material can emit a green laser.

Lutetium is also used in energy batteries and electroluminescent phosphors.