Lutetium pressure

Lanthanide bromides and iodides have found important applications in a completely different field. They are added as additives in high-pressure discharge lamps in the lighting industry to improve the arc stability and the colour quality. The latter is due to the contribution of the multiline spectrum of the doped rare earths which are added to the salt mixture. Lanthanide trihalides of dysprosium, holmium, thullium, gadolinium and lutetium are used frequently for this purpose (Hilpert and Niemann, 1997). 

The commercially important samarium-containing minerals are treated with concentrated sulfuric acid or, in the case of monazite, with a solution of sodium hydroxide (73%) at approximately 40°C (104°E) and under pressure. The element is separated from the solutions via solvent extraction or ion exchange. Sm salts are weakly yellow and may exhibit ion emission. Sm ions show luminescence and are sometimes used to generate lasers. Samarium is used in the manufacture of headphones and tape drivers, see ALSO Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Neodymium Praseodymium Promethium Terbium Ytterbium. 

The effect of chemical pressure on YbPtBi single crystals was studied by heat-capacity measurements on yttrium- and lutetium-doped samples (Lacerda et al. 1993). According to these measurements, the heavy-fermion state of this compound seems to be imchangeable by a relatively large amoimt of nonmagnetic doping (yttrium or lutetium). Furthermore, the heat capacity measurements reveal only a small pressure dependence when compared with other heavy-fermion materials. 

An LQ, Ito A, Goto T (2011) Two-step pressure sintering of transparent lutetium oxide by spark plasma sintering. J Eur Ceram Soc 31 1597-1602... 

Thulium (Tm) is a unique heavy lanthanide element. It is the last heavy lanthanide with an incomplete 4f shell. In the lanthanide series, thuhum is followed by ytterbium, which has a divalent electronic character and does not show the typical structural changes observed in other trivalent lanthanide elements. And the last element in the lanthanide series lutetium also has a completely filled 4f shell, and therefore is not expected to exhibit low symmetry structures at ultra high pressures. 

FIGURE 43 (A) ADXD spectra of Q-dfcc phases of lutetium under pressure, and (B) ADXD... 

The high-temperature polymorphic form for most of the rare earth metals just before melting is the bcc structure. Four of the trivalent lanthanides (holmium, erbium, thulium and lutetium) are monomorphic and do not form a bcc structure before melting at atmospheric pressure (see fig. 4). However, the bcc phase can be formed in holmium and erbium by the application of pressure (< 1 GPa), see section 3.7.1. The existence of the bcc phase in the lanthanides has been correlated with the d occupation number, which decreases along the lanthanide series, but increases... 

The light lanthanides also exhibit some unusual electrical and magnetic properties. The superconductivity of lanthanum has already been mentioned. But when its behavior is compared to the superconductivity in scandium, yttrium and lutetium, we find lanthanum is unusual. The ordering temperature T, and pressure dependence of T are both larger in lanthanum than in the other three superconductors (see section 3.7.3 and fig. 12a). 

Fig. 12. The pressure dependences of the superconductivity transition temperatures of several rare earth elements (a) lanthanum, lutetium, scandium and yttrium (after Wittig et al. 1979) and (b) cerium (after Probst and Wittig 1978).

The critical pressure, at which superconductivity begins (i.e. 7, = OK), is consistent with the Zspi values for these three metals. That is, the Pc of lutetium and yttrium are about the same, but significantly lower than that of scandium (fig. 12a), and 2jpj for yttrium and lutetium are nearly the same and about 3 to 4 times lower than 2spi for scandium. This supports the above analysis that the absence of superconductivity in lutetium, scandium and yttrium is due to spin fluctuations in these metals. 

Fig. 10.12. vs. pressure for lutetium. The numbers indicate the sequence of 11 measurements for one particular sample. As seen, is a reversible function of pressure. Two arrows indicate that no superconductivity was detected at those pressures down to — 20 mK. The curve is a smooth fit of the data (Probst, 1974). 

---