Neodymium deposition

Eecent work by L. M. Dermis2 and his co-workers has shown that electrolysis may be of considerable value in effecting a complete or partial separation of the oxides of the rare earth metals. Prom a neutral solution of the nitrates of neodymium, praseodymium, lanthanum, and samarium, nearly all the lanthanum is deposited as hydroxide in the last fractions discharged on the cathode. The hydroxides are deposited fractionally in order of their basicity, and the deposition is not dependent upon the... 

Nd2Ni04+5 powder was prepared by nitrate-citrate route as described by Courty, et a1. (1973). Stoichiometric amounts of neodymium and nickel oxides were dissolved in diluted nitric acid. After addition of a large excess of citric acid, the solution was dehydrated and heated until self-combustion of the precipitate to obtain submicronic precursor particles (Boehm, 2005). The final annealing was performed at 1000°C for 12 hours to obtain a single crystalline phase. The particles were then ball milled to obtain an average grain size (d0 5) of about 0.8 pm. A terpineol-based slurry was prepared from this powder and this was deposited on the electrolyte by screen printing and then sintered at 1100°C for three hours in air (Lalanne, 2008). 

The first neodymium-isotopic analyses aimed at characterizing the oceans closely followed the initial development of neodymium isotopes as a chronometer and tracer (Richard et al., 1976 DePaolo and Wasserburg, 1976a O Nions et al., 1977). O Nions et al. (1978) was the first to report neodymium (along with lead and strontium) isotopes in manganese nodules and hydrothermal sediments. They confirmed the distinction between continental and mantle provenances of lead in hydrogenous and hydrothermal manganese sediments, respectively. Consistent with the previous studies, they found that strontium in these deposits is derived from seawater. All of the neodymium-isotope ratios in their samples from the Pacific were similar and lower than the bulk... 

Secondary-ion mass spectrometry (SIMS) of a thin layer of nucleic acid bases deposited on a silver foil under bombardment with Ar ions at 3 kV gives intense pseudomolecular ions [M H] but practically no simple bond cleavage fragments. Another new technique is that of (pulsed) laser induced desorption (LD). When applied to nucleotide bases such as cytosine or adenine (266 nm, quadruplet neodymium laser or 347 nm, ruby laser) the technique has good detection limits, particularly for ions with a short lifetime (up to 100 nsec). The technique makes use of a time-of-flight instrument and is utilized in both modes, positive (PI) and negative ions (NI). Both bases exhibit an intense [BH]" ion. These results are similar to those obtained by Cf plasma desorption (PD). 

The deposited material in VINITI (No. 6103-73) contains a table of the enthalpies of the precipitation reaction but no primary experimental data. These enthalpies carry a positive sign, which contradicts the findings in [69SUP/MA1] for neodymium that is common to both investigations. Since the primary experimental data there show that the precipitation reaction is exothermic, the review has changed the sign of A //... 

Also elements 58 to 71 (partial deposition of lanthanum and neodymium has been reported). 

The world s resources of rare earth metals lie mainly in deposits of bastnasite in China. The chart below shows that mine production of the ore from China dominates the world s output. Bastnasite is a mixed metal carbonate fluoride, (M,M. ..)C03F. The composition varies with the source of the mineral, but the dominant component is cerium ( 50%), followed by lanthanum (20-30%), neodymium (12-20%) and praseod5mium (w5%). Each of the other rare earth metals (except for promethium which does not occur naturally) typically occurs to an extent of < 1 %. Monazite,... 

Deposition of crustal strontium and neodymium by hydrothermal fluids after eruption and crystallization of basalt lava... 

It surprises most people to learn that several of the so-called rare earth elements are not actually that rare compared to much more familiar elements. Neodymium, praseodymium, samarium, gadolinium, dysprosium, erbium, and ytterbium are all more abundant than more familiar elements like bromine, uranium, or tin. Europium, holmium, terbium, lutetium, and thulium are more abundant than iodine, silver, or mercury. Yet few people have even heard of most of the rare earths. The reason is that rare earths tend not to concentrate in large ore deposits in the way that better known metals do. Historically there have been fewer profits to be made from mining rare earth elements, and there have been fewer applications developed for them in industry. 

Cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) are called lanthanoid series. Lanthanum (La) which is a /-block element is also considered to be a lanthanoid. Therefore, the lanthanoid series comprises the fifteen elements with atomic numbers 57 (La) through 71 (Lu). Lanthanoids are grouped because of their chemical similarities and their properties only differ slightly with atomic number. All lanthanoids are relatively soft and reactive metals. Rare earth metals are a collection of seventeen chemical elements in the periodic table, namely. Sc, Y and the fifteen lanthanoids. Sc and Y are considered to be rare earths since they tend to occur in the same ore deposits as the lanthanoids and exhibit similar chemical properties. Table 2.86 summarizes some physical properties of a number of lanthanoids. 

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