Thulium

The rare metal thulium has almost no practical applications. What it can provide is available -more cheaply - from other lanthanides. It has been suggested, however, that the metal could be incorporated in ceramics, making them magnetic. If so, this material could be used in microwave equipment The y-radiation from the radioactive isotope °Tm has been examined for use in materials testing and as a portable X-ray source for medical use. 

Ytterbium fluoride is non-toxic and inert, and is not transparent to X-rays. Because of that the compound has been tested as an additive to composite plastic dental fillings. Traces of fluoride ions are continuously set free, giving protection against caries. In addition the ytterbium fluoride gives good X-ray contrast 

The energy of the lowest Coulomb transition in trivalent thulium, the Hg— F4 transition, is at just under 700 meV with transitions to the 

The experimental and calculated energies (in meV) of inter-multiplet transitions from the ground state multiplet of the 1 ion Tm doped in LaFj (Carnall et al. 1989) Tm metal (Osborn et al. 1990) calculation using the following parameters, Fj = 59.3 n  

The calculated structure factors are normalised to the intensity at k = 0, which has a 

Investigations of Coulomb transitions in intermediate valent thulium (and samarium) compounds are an obvious development in this field. 

Cotton, Simon (1991). Lanthanides and Actinides. New York Oxford University Press. 

Joseph J. Seaborg, Glenn T. and Morss, Lester R. (1986). The Chemistry of the Actinide Elements, 2nd edition. New York Chapman and Hall. 

Thulium is a silver-grey metal with a bright luster. Swedish chemist Per Theodor Cleve discovered the metal in 1879 while processing the ore er-bia. One of the materials Cleve extracted from the ore was a green substance he named thulia —a thulium oxide. The element s name is derived from an ancient name for northern Europe, Thule. 

Thulium is the least abundant of the naturally occurring rare earth elements, although it is believed to have a natural abundance similar to gold. 

An army medic takes an x ray of a simulated injury during a field test of an atom-powered portable x-ray unit. Portable x-ray units are powered by thulium, obviating the need for electricity. 

The photophysical analysis of the excitation and absorption spectra of [Tm(ppa)3 (H20)2], an a-substituted /3-diketonate investigated by Serra and coworkers showed a broad band centered around 335 nm, which is ascribed to the complex, since the ppa absorbance maximum is centered at 296 nm. The emission spectra (X xc = 335 nm) presented the characteristic bands of Tm + due to the G4 (478 nm), 64 p4 

FIGURE 10. [Eu(tta)3(tppo)2] complex used as the emitter in a three-layer OLED cell stmcture, sandwiched between an ito cathode and an aluminum anode. Reproduced with permission from Reference 134, Copyright 2002 Sociedade Brasileira de Ffsica 

Although several methods may be used to fabricate the organic layers in OLEDs, such as thermal evaporation, Langmuir-Blodget deposition or spin coating from solutions, RE + /3-diketonates usually are deposited by thermal evaporation techniques, under high vacuum ca 10 Pa) thus, volatility and thermal stability of the diketonates are required.  

OLEDs are nowadays the most important type of light source for artificial lighting, making them potential candidates in the development of full-color flat panel display devices. Challenging problems to be addressed are emission color, emission efficiency and device lifetime. The emission color problem results from the broad emission bands exhibited by electroluminescent devices containing organic emitting layers, since pure and sharp emission bands from these materials, a requisite for display applications, are 

SYMBOL Tm PERIOD 6 SERIES NAME Lanthanide ATOMIC NO 69 

ATOMIC MASS 168.9342 amu VALENCE 3 OXIDATION STATE +3 NATURAL STATE  

ORIGIN OF NAME Named for Thule, the Greek word for Scandinavia, the most northerly habitable land in ancient mythology. 

ISOTOPES There are a total of 46 isotopes of thulium. One of these, Tm-169 is the only stable isotope of thulium and accounts for the total atomic mass of the element. All the other isotopes are artificially produced and radioactive and have half-lives ranging from a few microseconds to two years. 

Thulium is a naturally occurring rare metal that exists is very small amounts mixed with other rare-earths. It is a bright silvery metal that is malleable and ductile and can be cut easily with a knife. Its melting point is so high that it is difficult to force it into a melted state. Its vapor pressure is also high, and thus, much of the molten thulium evaporates into the atmosphere. Its melting point is 1,545°C, its boiling point is 2,950°C, and its density is 9.32g/cm.  

There are only two reported values for the solubihty constant of Tm(OH)3(s). Moeller and Kremers (1944) quote an average value for log of 18.5 obtained from nitrate, sulfate and acetate solutions. This value is considered to make Tm(OH)j(s) too soluble, but the measurements made by Moeller and Kremers were on a hydrous hydroxide which is most hkely amorphous and, therefore, will be more soluble than a crystalline form. This value for the solubility constant is not retained by this review. From the data provided by Diakonov, Ragnarsdottir 

Stability constants for TmOH have only been reported by Klungness and Byrne (2000) and Frolova, Kumok and Serebrennikov (1966). These data are listed in Table 8.47. Klungness and Byrne measured the stability of TmOH across the temperature range from 25 to 55 °C and in 0.1 and 0.7 moll NaClO. They determined an enthalpy for reaction of TmOH on the basis of the variation in the stability as a function of temperature. Frolova et al. measured the stability at 25 °C and in 0.3 mol 1 NaClO. The results from the two studies are in reasonable agreement. 

Fatin-Rouge and Biinzli (1999) is the only study to give stability constant data for the higher monomeric species of thulium. The conclusion reached with the other 

There have been no reported stability constants for polymeric hydrolysis species of thulium. 

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Some nut trees accumulate mineral elements. Hickory nut is notable as an accumulator of aluminum compounds (30) the ash of its leaves contains up to 37.5% of AI2O2, compared with only 0.032% of aluminum oxide in the ash of the Fnglish walnut s autumn leaves. As an accumulator of rare-earth elements, hickory greatly exceeds all other plants their leaves show up to 2296 ppm of rare earths (scandium, yttrium, lanthanum, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The amounts of rare-earth elements found in parts of the hickory nut are kernels, at 5 ppm shells, at 7 ppm and shucks, at 17 ppm. The kernel of the Bra2d nut contains large amounts of barium in an insoluble form when the nut is eaten, barium dissolves in the hydrochloric acid of the stomach. 

The classical methods used to separate the lanthanides from aqueous solutions depended on (i) differences in basicity, the less-basic hydroxides of the heavy lanthanides precipitating before those of the lighter ones on gradual addition of alkali (ii) differences in solubility of salts such as oxalates, double sulfates, and double nitrates and (iii) conversion, if possible, to an oxidation state other than -1-3, e g. Ce(IV), Eu(II). This latter process provided the cleanest method but was only occasionally applicable. Methods (i) and (ii) required much repetition to be effective, and fractional recrystallizations were sometimes repeated thousands of times. (In 1911 the American C. James performed 15 000 recrystallizations in order to obtain pure thulium bromate). 

Thulium, Tm P. T. Cleve 1879 Latin Thule, most northerly land ... 

Di-rerr-butylsodium pyrrolate serves as a source of the complexes of lanthanides [93CB2657 95JOM(495)C12]. Thus, with cyclooctadienyl chlorides of samarium, thulium, and lutetium, it affords species 89 [96JOM(507)287]. The N-coordinated samarium(II) calix-pyrrole complex is known [99AG(E)1432]. 

Thulium-170 127 days 0.085 Light alloys, thin sections... 

Lanthanum Comm Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium... 

Bivalence is similarly shown for europium, and trivalence for the elements gadolinium to thulium. 

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