Neodymium solubility constant

The solubility of lanthanum, neodymium and gadolinium hydroxide has been studied over an extensive temperature range, with data available for neodymium hydroxide available from 0 to 300 °C. All three solubility constants vary linearly with respect to the inverse of absolute temperature (Figure 8.8). The enthalpies of reaction calculated from the linear relationships are all within 10% indicating a similar functionality of the solubilities as a function of temperature as would be expected. The calculated enthalpy of reactions are -137.2 3.8, -139.8 1.7 and -129.5 4.4 kj mol for lanthanum, neodymium and gadolinium hydroxide, respectively. 

Figure Solubility constant (log of LnfOHjjfs) (lanthanum, neodymium and...

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... 

Moreover, they are chemically similar. Both display very limited solubility in water, and differences in chemical behavior are mainly associated with atomic size. Lutetium and hafnium are also refractory elements during nebula condensation, and thus their relative abundance in the Earth are chondritic, however, at the time of writing the value of the bulk Earth Hf/ Hf ratio and the Lu decay constant are being debated (Table 1). Neodymium- and hafnium-isotope ratios in this paper will be expressed as parts per 10 deviations from the bulk Earth values, viz., as s d and sht- Eor example,... 

Figure 53 shows the isothermal section of the Sc-Nd-Si system at 600 C which was determined by Banakh and Kotur (1998). The binary silicides NdSi2 t and NdSi dissolve 15 and 7 at.% Sc, respectively. The solubility of the third component in other neodymium and scandium binary silicides does not exceed 2 at.%. Five ternary compoimds exist in this system (see table 19). One of them, (4) in fig. 53, has variable composition of Sc and Nd. Four other have practically constant composition. 

M., and Sasaki, N. (1993) Neodymium(III) hydrolysis constants and solubilities of Nd(III) hydroxide. Nippon Kagaku Kaishi,... 

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