Neutron Diffraction Studies of Molten Salts

The resulting structure factor is still a linear superposition of the three partial structure factors for the various types of pairs of ions, 1-J, 1-1, and J-J  

Variation of b in three different experiments by varying the isotopic composition permits the three independent linear equations to be solved to yield the three partial structure factors. The Fourier transform of each of these yields the partial pan-correlation functions gu(r) for catimi-anion correlation, and gn(r) and gjj(r) for correlations of ions of the same sign. The Neutron diffraction with isotope substitution (NDIS) method permits this variation of b, because different isotopes of the elements have different b values, some of which may even be negative. 

Comparison of the data in Tables 3.4 and 3.5 for salts common to the two tables shows the first peak distances obtained by the NDIS method to be 3 % shorter on the average, and to be 4 % shorter than the sum of the room temperature ionic radii r+ + r. These apparent discrepancies have not been explained. 

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