Neodymium,

SYMBOL Nd PERIOD 6 SERIES NAME Lanthanide ATOMIC NO 60 

ATOMIC MASS 144.24 amu VALENCE 3 OXIDATION STATE -i-3 NATURAL STATE Solid 

ORIGIN OF NAME Derived from the two Greek words neos and didymos. When combined, they mean new twin.  

ISOTOPES There are 47 isotopes of neodymium, seven of which are considered stable. Together the stable isotopes make up the total abundance in the Earth s crust. Two of these are radioactive but have such long half-lives that they are considered stable because they still exist on Earth. They are Nd-144 (half-life of 2.29x10+ years) and Nd-150 (half-life of 6.8x10+ years). All the other isotopes are synthetic and have half-lives ranging from 300 nanoseconds to 3.37 days. 

Neodymium is the third most abundant rare-earth element in the Earths crust (24 ppm). It is reactive with moist air and tarnishes in dry air, forming a coating of Nd O, an oxide with a blue tinge that flakes away, leaving bare metal that then will continue to oxidi2e. 

Drexler, K Eric. (1987). Engines of Creation The Coining Era of Nanotechnology. Reprinted and adapted by Russell Whitaker, with permission. Available from http //www.foresight.org/EOC/index.html . 

Eeynman, Richard. There s Plenty of Room at the Bottom. Available from http // www.zyvex.com/nanotech/feynman.html . 

Gordon E. Cramming More Components onto Integrated Circuits. Available from http //www.intel.com/research/silicon/mooreslaw.htm . 

Whitesides, G., and Alivisatos, P. (1999). Fundamental Scientific Issues for Nanotechnology. In Nanotechnology Research Directions IWGN Workshop Report Vision for Nanotechnology Research and Development in the Next Decade, ed. by M. C. Roco, S. Williams, and P. Alivisatos. Available from http //itri.loyola.edu/nano /IWGN.Research.Directions . 

Neodymium oxide was first isolated from a mixture of oxides called didymia. The elemeut ueodymium is the secoud most abuudaut lanthanide element in the igneous rocks of Earth s crust. Hydrated neodymium(lll) salts are reddish and anhydrous neodymium compounds are blue. The compoxmds neodymium(III) chloride, bromide, iodide, nitrate, perchlorate, and acetate are very soluble neodymium sulfate is somewhat soluble the fluoride, hydroxide, oxide, carbonate, oxalate, and phosphate compounds are insoluble. 

Magnet type Remanence (mT) Depending on the variety Intrinsic coercive force, Hci (kA/m) Depending on the variety Maximum operating temperature (°C) Depending on the variety 

Following are listed applications of neodymium magnets (Brown et al. 2002). 

Disk-drive spindle motors and voice coil motors 

Electric fuel pumps Instrumentation gauges Brushless DC motors Actuators Alternators Consumer electronics VCRs and camcorders Cameras 

Air conditioners Water pumps Security systems Eactory automation Magnetic couplings Pumps Motors Servo motors Generators Bearings Medical industry MRl 

Stirling et al. (1986) report seeing a peak at 240 meV which decreases smoothly with K. A more detailed investigation has confirmed that the transition at 237 meV 

Data reported for the solubility constant of Nd(OH)3(s) are listed in Table 8.26. The data cover a wide temperature range of0 - 300 C and a range in ionic strength of 0-5.61 molkg . At temperatures other than 25 C, the data were acquired using a sodium triflate electrolyte at 0-1 mol kg . The vast majority of data derive from Wood et al. (2002) but a few other data at near ambient temperature and zero ionic strength have been accepted. Neck et al. (2009) measured the solubility in 0-5 mol 1 NaCl, and these data have been re-evaluated in the present work to obtain the relevant solubility and stability constants. 

There are only a few other data for the solubility of Nd(OH)3(s) that have been reported for fixed ionic strength. Neck et al. (2009) measured the solubility of neodymium hydroxide in NaCl media. Values determined from their measurements at low ionic strength (0.1 and 0.5 moll ) are in very good agreement with those of Wood et al. (2002). At higher ionic strengths, there is a departure in the solubiUty values, as might be expected in these different electrolytes. All of the data calculated from the measurements of Neck et al. are retained in this review. None of the other solubility constant data are consistent with those reported by 

TCO / (reported) Medium /(mol kg- ) mx (molkg- ) log (reported) log (accepted) References 

Wood et al. (2002), except possibly for the value of Rao, Rai and Felmy (1996) at the highest of the two temperatures (90 C) they reported. However, Rao et al. found only a relatively small dependence on temperature, their solubility at 25 C being nearly four orders of magnitude different to that reported by Wood et al. (this difference cannot be explained by either different electrolytes or solid phases used in the two studies). This small dependence on temperature is inconsistent with the observed behaviour of Nd(OH)3(s), as well as other trivalent lanthanide hydroxide phases (Deberdteta/., 1998),and consequently the dataofRao, Rai and Felmy (1996) are not accepted in this review. 

An analysis of the stability constant data derived for NdOH from the measurements of Neck et al. (2009) was also undertaken using the extended specific ion interaction theory. The values derived for the ion interaction coefficients were =-0.56 0.06 kg mol and Ae2 =0.44 0.09 kg mol .  

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The appearance of a peak between those for neodymium (60) and samarium (62) was then strong evidence for the existence of promethium (61). 

Another characteristic change across the lanthanide series is that of the paramagnetism of the ions this rises to a maximum at neodymium, then falls to samarium, then rises to a second maximum at gadolinium before falling finally to zero at the end of the series. 

Praseodymium is soft, silvery, malleable, and ductile. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that spalls off when exposed to air. As with other rare-earth metals, it should be kept under a light mineral oil or sealed in plastic. 

Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

The element may be obtained by separating neodymium salts from other rare earths by ion-exchange or solvent extraction techniques, and by reducing anhydrous halides such as NdFs with calcium metal. Other separation techniques are possible. 

The metal has a bright silvery metallic luster. Neodymium is one of the more reactive rare-earth metals and quickly tarnishes in air, forming an oxide that spalls off and exposes metal to oxidation. The metal, therefore, should be kept under light mineral oil or sealed in a plastic material. Neodymium exists in two allotropic forms, with a transformation from a double hexagonal to a body-centered cubic structure taking place at 863oC. 

Natural neodymium is a mixture of seven stable isotopes. Fourteen other radioactive isotopes are recognized. 

Neodymium has a low-to-moderate acute toxic rating. As with other rare earths, neodymium should be handled with care. 

Neodymium and YAG Lasers. The principle of neodymium and YAG lasers is very similar to that of the ruby laser. Neodymium ions (Nd +) are used in place of Cr + and are often distributed in glass rather than in alumina. The light from the neodymium laser has a wavelength of 1060 nm (1.06 xm) it emits in the infrared region of the electromagnetic spectrum. Yttrium (Y) ions in alumina (A) compose a form of the naturally occurring garnet (G), hence the name, YAG laser. Like the ruby laser, the Nd and YAG lasers operate from three- and four-level excited-state processes. 

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