1878, Swiss chemists Jean Charles and G de Nakel discovered a new rare earth element in erbium. In order to commemorate the small village named Yteerby near Stockholm where yttrium was discovered, the new element was named Ytterbium, and the element symbol Yb was translated into Chinese as "Yteerby".
Although ytterbium ranks behind thulium in lanthanide series, its crustal abundance reaches 3.3ppm, which is not only higher than other medium and heavy rare earths such as terbium, holmium, thulium and lutetium, but even higher than Europium (2.2 ppm). Ytterbium mainly exists in ionic rare earth minerals, xenotime, Heixi gold mine and other medium and heavy rare earth minerals, with 7 natural isotopes. In Xunwu, Jiangxi, the content of ytterbium in rare earth is higher than that of europium, and in Longnan, the content of ytterbium is about 10 times that of europium, so ytterbium is relatively rich in heavy rare earth elements, which provides a certain resource base for its development and application.
Ytterbium metal is silvery gray, malleable and soft. Ytterbium can be slowly oxidized by air and water at room temperature. Similar to samarium and europium, ytterbium is a rare earth with variable valence, which can be in a positive trivalent state or a positive divalent state. Because of this valence-changing characteristic, it is not suitable to prepare ytterbium metal by electrolysis instead of reductive distillation. Usually, lanthanum is used as reducing agent, and reduction distillation is carried out by using the difference between the high vapor pressure of ytterbium and the low vapor pressure of lanthanum. The ytterbium can also be directly extracted from thulium ytterbium lutetium concentrate by reductive distillation under the conditions of > 1 100℃ and < < 0. 133Pa. Like samarium and europium, ytterbium can also be separated and purified by wet reduction. Usually, rich thulium, ytterbium and lutetium are used as raw materials, and ytterbium is reduced to divalent after dissolution, which leads to significant differences in properties and then separated from other trivalent rare earths. High purity ytterbium oxide is usually prepared by extraction chromatography or ion exchange.
Ytterbium, as a heavy rare earth element, has limited available resources and expensive products, which limits its application research. With the emergence of high-tech such as optical fiber communication and laser, ytterbium has gradually found its application stage.
In recent years, ytterbium has appeared and developed rapidly in optical fiber communication and laser technology.
With the development of "information superhighway", computer networks and long-distance optical fiber transmission systems require higher and higher performance of optical fiber materials for optical communication. Ytterbium ion can be used as optical fiber amplification material for optical communication, just like erbium and thulium because of its excellent spectral characteristics. Although rare earth element Er is still the main character in the preparation of fiber amplifier, the gain bandwidth of traditional erbium-doped optical fiber is small (30nm), which is difficult to meet the requirements of high-speed and large-capacity information transmission. However, near 980nm, the absorption cross section of Yb3+ ion is much larger than that of Er3+ ion. The light of 1530nm can be greatly enhanced by the sensitization of Yb3+ and the energy transfer of erbium and ytterbium, thus greatly improving the optical amplification efficiency.
In recent years, erbium-doped ytterbium phosphate glass has been favored by more and more researchers. Phosphate and fluorophosphate glasses have good chemical and thermal stability, wide infrared transmittance and large non-uniform broadening characteristics, and are ideal materials for broadband and high-gain erbium-doped amplification fiber glasses. If Yb3+ ions are introduced into it to make erbium-doped ytterbium fiber, the amplification performance of the fiber can be greatly improved. The high concentration erbium-doped, ytterbium-doped and phosphate-doped fibers (core diameter 7μm, numerical aperture 0.2) developed in China are suitable for all-wave amplifiers. Using a 980nm semiconductor laser, a net gain of 3.8dB is achieved for small signals within the communication window of 1.5μm, and the gain per unit length is 2.5dB/cm, which is two orders of magnitude higher than that of the current commercial synchronous amplifier.
Yb3+-doped fiber amplifier can realize power amplification and small signal amplification, so it can be used for fiber sensor, free space laser communication and ultrashort pulse amplification.
At present, China has built an optical transmission system with the largest single channel capacity and the fastest speed in the world, and has the widest information superhighway in the world. Yb-doped and other rare earth-doped fiber amplification and laser materials play a key role in it.
Ytterbium's spectral characteristics are also used as high-quality laser materials, not only as laser crystals, but also as laser glasses and fiber lasers.
Yb-doped laser crystals have formed a huge series as high-power laser materials, including Yb: YAG, Yb: GGG, Yb: S-FAP and Yb:S-FAP.
Semiconductor laser (LD) is a new type of solid-state laser pumping source. Yb: YAG has many characteristics and is suitable for high-power LD pumping, and has become a laser material for high-power LD pumping. Ytterbium sulfur FAP crystal may be used as laser material to realize laser nuclear fusion in the future, which has attracted people's attention. In tunable laser crystals, the wavelength of Cr-doped Yb: Ho: Yagg (Cr, Yb, Ho: Yagg) is continuously adjustable between 2.84 and 3.05 microns. According to statistics, most infrared missile warheads used internationally use 3-5μm medium-wave infrared detectors, so the development of Cr, Yb, Ho: YSGG lasers can provide effective interference to the countermeasures of mid-infrared guided weapons, which has important military significance.
At present, China has made a series of innovative achievements in Yb-doped laser crystals (Yb: YAG, Yb: FAP, Yb: SFAP, etc.). ), and solved many key technologies such as crystal growth, fast, pulsed, continuous and adjustable laser output. The research results have been applied to national defense, industry and scientific engineering, and ytterbium-doped crystal products have been exported to the United States.
Another kind of Yb laser material is laser glass. Various laser glasses with high emission cross section have been developed, such as germanium tellurite, silicon niobate, borate and phosphate. Because glass is easy to shape, can be made into large size, and has the characteristics of high transmittance and high uniformity, it can be made into a high-power laser. The familiar rare earth laser glass is mainly neodymium glass, which has a history of more than 40 years and has mature manufacturing and application technology. It has always been the first choice material for high-power laser devices, and has been used in nuclear fusion experimental devices and laser weapons. The high-power laser devices Shen Guang 1 and Shen Guang 2 built in China with Nd glass as the main laser medium have reached the advanced level in the world. However, laser Nd glass is now facing a strong challenge from laser Yb glass.
In recent years, a lot of research shows that many properties of laser ytterbium glass are better than neodymium glass. Because Yb-doped luminescence has only two energy levels, the energy storage efficiency is high. Under the same gain, the energy storage efficiency of Yb-doped glass is 16 times higher than that of Nd-doped glass, and the fluorescence lifetime is 3 times longer than that of Nd-doped glass. At the same time, it has the advantages of high doping concentration, wide absorption bandwidth, and can be directly pumped by semiconductor, which is very suitable for high-power lasers. But the practical application of ytterbium laser glass often needs the help of neodymium. For example, as a sensitizer, Nd3+ can make ytterbium laser glass run at room temperature and realize laser emission with the wavelength of 1.06 micron ... Therefore, ytterbium and neodymium are both competitors and partners in laser glass.
Many luminescent properties of ytterbium laser glass can be improved by adjusting the glass composition. With high-power laser as the main development direction, the laser made of ytterbium laser glass is more and more widely used in modern industry, agriculture, medicine, scientific research and military.
Taking the energy produced by nuclear fusion as energy has always been a long-awaited goal, and the realization of controlled nuclear fusion will be an important means for human beings to solve energy problems. Yb-doped laser glass has become the first choice for upgrading inertial confinement fusion (ICF) in 2 1 century due to its excellent laser performance.
Laser weapons use the huge energy of laser beams to attack and destroy targets, which can generate hundreds of millions of degrees of high temperature and directly attack at the speed of light, which means that it can mean that it has great lethality, and is especially suitable for air defense weapon systems in modern wars. The excellent properties of Yb-doped laser glass make it an important basic material for manufacturing high-power and high-performance laser weapons.
Fiber laser is a new technology that is developing rapidly at present, and it also belongs to the application category of laser glass. Fiber laser is a laser with optical fiber as the laser medium, which is the product of the combination of optical fiber and laser technology. It is a new laser technology developed on the basis of erbium-doped fiber amplifier (EDFA) technology. Fiber laser is composed of semiconductor laser diode as pump source, optical fiber as waveguide and gain medium, grating optical fiber, coupler and other optical elements. It does not need mechanical adjustment of optical path, and has compact mechanism and easy integration. Compared with traditional solid-state lasers and semiconductor lasers, it has technical and performance advantages such as high beam quality, good stability, strong anti-environmental interference ability, no adjustment, no maintenance and compact structure. Because the doped ions are mainly Nd+3, Yb+3, Er+3, TM+3 and HO+3, all of which use rare earth fiber as gain medium, the fiber laser developed at present can also be called rare earth fiber laser.
High-power Yb-doped double-clad fiber laser is the research focus of solid-state laser technology in recent years. It has the advantages of good beam quality, compact structure and high conversion efficiency, and has a wide application prospect in industrial processing and other fields. Double-clad Yb-doped fiber is suitable for semiconductor laser pumping, which has the characteristics of high coupling efficiency and high laser output power, and is the main development direction of Yb-doped fiber. At present, China's double-clad ytterbium-doped fiber technology is equivalent to the advanced level abroad. Ytterbium-doped fiber, double-clad ytterbium-doped fiber and erbium-doped ytterbium-doped fiber developed in China have reached the advanced level of similar products abroad in terms of performance and reliability, and have cost advantages and core patented technologies of many products and methods.
The world-famous German IPG Laser Company recently announced that their newly-developed Yb-doped fiber laser system has excellent beam characteristics, with a pumping life of over 50,000 hours, a central emission wavelength of 1.070nm- 1.080nm and an output power of up to 20KW, which has been applied to fine welding, cutting and rock drilling.
Laser materials are the core and foundation of developing laser technology. There has always been a saying in the laser industry that "a generation of materials, a generation of devices". Only by possessing excellent laser materials and integrating other related technologies can we develop advanced and practical laser devices. Ytterbium-doped laser crystal and laser glass, as a new force of solid laser materials, are promoting the innovative development of optical fiber communication and laser technology, and will make important contributions to cutting-edge laser technologies such as high-power nuclear fusion laser, high-energy PW laser and high-energy weapon laser.
In addition, according to some articles, ytterbium is also used as phosphor activator, radio ceramics, electronic computer storage element (magnetic bubble) additive and optical glass additive. It should be pointed out that both ytterbium and yttrium are rare earth elements. Although English names and element symbols are obviously different, Chinese phonetic syllables are the same. In some Chinese translations, yttrium is sometimes mistaken for ytterbium. At this time, it is necessary to trace back to the original text and confirm it with element symbols.