thulium


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thulium

(tho͞o`lēəm) [from Thule, an ancient name for Scandinavia], metallic chemical element; symbol Tm; at. no. 69; at. wt. 168.93421; m.p. about 1,545°C;; b.p. 1,947°C;; sp. gr. 9.3; valence +3. Thulium is a soft, malleable, ductile, lustrous silver-white metal. It is one of the rare-earth metalsrare-earth metals,
in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, which is not found in nature, is not usually considered a rare-earth metal.
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 of the lanthanide serieslanthanide series,
a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic number 57) is not always considered a member of the series.
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 in Group 3 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
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. It does not tarnish rapidly in dry air but should be protected from moisture. It forms compounds with oxygen and the halogens, most of which are light green. The oxide, Tm2O3, is called thulia. Thulium is the least abundant of the rare-earth metals. It is found in the minerals gadolinite and euxenite and in monazite, the chief commercial source. The metal can be obtained by chemical reduction of its compounds. The pure metal and compounds have few commercial uses, but they are often used without purification in combination with the other rare-earth metals and compounds, e.g., in lighter flints and carbon electrodes for arc lighting. Although the only naturally occurring isotope (thulium-169) is stable, there are 15 unstable isotopes. Thulium-170 (half-life about 129 days), prepared by irradiating thulium-169 in a nuclear reactor, emits X rays; it is used in portable X-ray sources. Thulium was discovered in 1879 by P. T. Cleve.

thulium

[′thü·lē·əm]
(chemistry)
A rare-earth element, symbol Tm, of the lanthanide group, atomic number 69, atomic weight 168.9342; reacts slowly with water, soluble in dilute acids, melts at 1550°C, boils at 1727°C; the dust is a fire hazard; used as x-ray source and to make ferrites.

thulium

a malleable ductile silvery-grey element occurring principally in monazite. The radioisotope thulium-170 is used as an electron source in portable X-ray units. Symbol: Tm; atomic no.: 69; atomic wt.: 168.93421; valency: 3; relative density: 9.321; melting pt.: 1545°C; boiling pt.: 1950°C
References in periodicals archive ?
Two-micrometer thulium laser resection of the prostate-tangerine technique in benign prostatic hyperplasia patients with previously negative transrectal prostate biopsy.
Considering, the probability of occurrence of transition from state 3 to state 1 is more as compared either to that from state 3 to state 0 or from state 1 to state 0 and also, assuming total population inversion, the metastable population densities of thulium ion becomes:
Shimizu "S-band Thulium-doped fiber amplifier employing high Thulium concentration doping technique", J.
All procedures were performed by one doctor with more than 10 years of experience with TURP and 4 years of experience with thulium laser resection of the prostate.
Huang, "Sensitized thulium ultraviolet upconversion luminescence in [Tm.sup.3+]/[Yb.sup.3+]/[Nd.sup.3+] triply doped nanoglass ceramics," Optics Letters, vol.
Kitamura, "Calcium sulfate activated by thulium or dysprosium for thermoluminescence dosimetry," Health Physics, vol.
Additionally, Tm-DOTMA (thulium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethyl-1,4,7,10- tetraacetic acid) was injected the same manner.
The heavy rare earth element concentrate from the project contained 24.54% samarium, 4% europium, 21.82% gadolinium, 25.65% dysprosium, 3.14% holmium, 5.96% erbium, 1.71% thulium, 6.09% ytterbium, and 1.08% lutetium.
THULIUM 20 - 8 + 21 + 12 + [square root of (9] x [21 - 13]) = 69
Novel energy sources, including a diode laser and a thulium laser, have been shown to be effective for BPE treatment.
'long persistent phosphors' and solar panels) that are under development, some of which will require the more obscure heavy rare earths such as ytterbium, erbium, holmium and thulium.
21 Sc (Scandium) * Parodi 1998 64 Gd (Gadolinium)* 39 Y (Yttrium) * 65 Tb (Terbium) 57 La (Lanthanum) * 66 Dy (Dysprosium)* 58 Ce (Cerium) * 67 Ho (Holmium) 59 Pr (Praseodymum) * 68 Er (Erbium) 60 Nd (Neodymum) * 69 Tm (Thulium) 61 Pm (Promethium) 70 Yb (Ytterbium) 62 Sm (Samarium) * 71 Lu (Lutetium) 63 Eu (Europium) * present at Trimouns (Moelo et al., 1974) Table 2.