Behavior Of Sm Research Articles

Electrochemical studies of trivalent californium and selected trivalent lanthanides in aqueous solution

D.c. polarographic and cyclic voltammetric studies have been carried out on aqueous solutions (10 −4−10 −3 M) of 249Cf, Sm and Gd. From the present data and the established electrochemical behavior of Sm and Gd, it can be inferred that Cf(III) is reduced in two steps at the mercury-drop electrode, first to Cf(II), followed by the Cf(II) being reduced to Cf(Hg). The potentials for the two electrochemical steps are −1.47 and −1.68V vs NHE, respectively.

Petrogenetic mixing models and Nd-Sr isotopic patterns

The possible Nd and Sr isotopic variations which would result from assimilation of continental crust by mantle-derived magmas can be systematized by considering the chemical and isotopic compositions of the magmas and models for layering within the continental crust. These systematics may provide a valuable framework for studying crustal contamination, the formation of magmas within the crust, and the chemical and age structure of continental segments. The isotopic patterns arise from 1. (1) the overall contrast in Nd and Sr isotopic composition between old continental crust and mantle magma sources, 2. (2) regularities in the variations of 143Nd 144Nd and 87Sr 86Sr in crustal rocks which are related to age and the contrasting geochemical behavior of Sm and Nd relative to Rb and Sr. Consideration of two-component mixing models suggests that the correlation of initial Nd and Sr isotopes in selected young basalts could represent a mixing line, possibly between mantle reservoirs of distinct chemistry and age. However, the possibility that the trend results from mixing of old low- Sm Nd , high- Rb Sr crustal material with complementary high- Sm Nd , low- Rb Sr mantle reservoirs cannot be eliminated. Such recycling of crust into the mantle could occur in subduction zones. One problem with a recycling model to explain the correlation is that it requires the crustal endmember to have chemical and isotopic properties which do not appear to be common in crustal rocks.

A formulation of the determinism hypothesis

The author tries to formulate what a determinist believes to be true. The formulation is based on some concepts defined in a systems-theoretical manner, mainly on the concept of an experiment over the sets A m (a set of m-tuples of ‘input values’) and B n (a set of n-tuples of ‘output values’) in the time interval (t 1, ..., t k ) (symbolically E[t 1,..., t k , A m , B n ]), on the concept of a behavior of the system S m,n (=(A m , B n )) on the basis of the experiment E[t 1, ..., t k , A m , B n ] and, indeed, on the concept of deterministic behavior .... The resulting formulation of the deterministic hypothesis shows that this hypothesis expresses a belief that we always “could find” some “hidden parameters”.

Complexation behavior of the lanthanide-iminodiacetic acid system and its possible application to the separation of light rare earths from transplutonium elements by ion exchange

It is stated that in an earlier study of the complexing behavior of the Am-iminodiacetic acid system five complexes were observed in the pH range 3.5 to 9.5. In the present studies the complexing behavior of Sm with iminodiacetic acid was investigated and three complexes were found for this system. Distribution coefficients were also measured for three light rare earths (Eu, Ce and Pm) and for Am and Cm with respect to Dowex 50W-X12 resin in the presence of the complexing agent, together with the possibility of mutual separation. A low Am/Cm separation factor was obtained due to the similarity of their chemical behavior, but the results obtained for Ce, Pm, and Eu allow a prediction of a separation factor of about 2 for adjacent rare earths. Differences were found in the complexing behavior of iminodiacetic acid with light rare earths and the transplutonium elements, and these differences suggest possible application of competitive complexation to the separation of the two groups by ion exchange. (UK)