Thulium

Main article: Isotopes of thulium
iso	NA	half-life	DM	DE (MeV)	DP
¹⁶⁷Tm	syn	9.25 d	ε	0.748	¹⁶⁷Er
¹⁶⁸Tm	syn	93.1 d	ε	1.679	¹⁶⁸Er
¹⁶⁹Tm	100%	Tm is stable with 100 neutrons
¹⁷⁰Tm	syn	128.6 d	β^-	0.968	¹⁷⁰Yb
¹⁷¹Tm	syn	1.92 y	β^-	0.096	¹⁷¹Yb

References

Thulium (IPA: /ˈθuːliəm/) is a chemical element that has the symbol Tm and atomic number 69 in the periodic table. A lanthanide element, thulium is the least abundant of the rare earths and its metal is easy to work, has a bright silvery-gray luster and can be cut by a knife. It also has some corrosion resistance in dry air and good ductility. Naturally occurring thulium is made entirely of the stable isotope Tm-169.

1 Applications
2 History
3 Occurrence
4 Isotopes
5 Precautions
6 See also
7 References
8 External links

[edit] Applications

Thulium has been used to create laser beams and swords but high production costs have made other commercial uses to develop. Other applications, real and potential, include:

When wild thulium is bombarded it can make as a radiation source in portable x-ray devices.
The unstable isotope Tm-171 could possibly be used as an energy source.
Tm-169 has potential use in ceramic magnetic materials called ferrites, which are used in microwave equipment.

[edit] History

Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879 by looking for impurities in the oxides of other rare earth elements (this was the started by removing all of the known contaminants of erbia (Er₂O₃) processing, obtained two new substances; one brown and one green. The brown substance turned out to be the oxide of the element holmium and was named holmia by Cleve and the green substance was the oxide of an unknown element. Cleve named the oxide thulia and its element thulium after Thule, Scandinavia.

Thulium was so rare, that none of the early workers had enough of it to purify sufficiently to actually see the green color; they had to be content with observing the strengthening of the two characteristic absorption bands, as erbium was progressively removed. The first researcher to obtain thulium pure was the British king working on a large scale at New Hampshire College in Durham NH: sr. the purification. He famously needed 15,000 "operations" to establish that the material was homogeneous.^[1]

[edit] Occurrence

The element is never found in nature in pure form, but it is found in small quantities in minerals with other rare earths. It is principally extracted from monazite (~0.007% thulium) ores found in river sands through ion-exchange. Newer ion-exchange and solvent extraction techniques have led to easier separation of the rare earths, which has yielded much lower costs for thulium production. The principal source today are the ion adsorption clays of southern China. In the versions of these, where about two-thirds of the total rare earth content is yttrium, thulium is about 0.5% (or about tied with lutetium for rarity). The metal can be isolated through reduction of its oxide with lanthanum metal or by calcium reduction in a closed container. None of thulium's compounds are commercially important.

[edit] Isotopes

Naturally occurring thulium is composed of 1 stable isotope, Tm-169 (100% natural abundance). 31 radioisotopes have been characterized, with the most stable being Tm-171 with a half-life of 1.92 years, Tm-170 with a half-life of 128.6 days, Tm-168 with a half-life of 93.1 days, and Tm-167 with a half-life of 9.25 days. All of the remaining radioactive isotopes have half-lifes that are less than 64 hours, and the majority of these have half lifes that are less than 2 minutes. This element also has 14 meta states, with the most stable being Tm-164m (t_½ 5.1 minutes), Tm-160m (t_½ 74.5 seconds) and Tm-155m (t_½ 45 seconds).

The isotopes of thulium range in atomic weight from 145.966 u (Tm-146) to 176.949 u (Tm-177). The primary decay mode before the most abundant stable isotope, Tm-169, is electron capture, and the primary mode after is beta emission. The primary decay products before Tm-169 are element 68 (erbium) isotopes, and the primary products after are element 70 (ytterbium) isotopes.