Electron distribution and characteristic temperature variation at low temperatures in magnesium and ruthenium

Abstract

A number of X-ray investigations on metals have indicated that over and above a uniform background of electron distribution, there exists electron density concentration at particular sites in the lattice. Brindley and Ridley attributed the deviations of the measured X-ray scattering factors of ruthenium from a smooth curve to the existence of electron concentration at the mid-point of all the basal triangles formed by ruthenium atoms. Brill et al. discussed for magnesium a similar concentration at only those triangle mid-points which are surrounded by five magnesium atoms. A similar effect, enhanced at 90°K., was found by Griffith and Harris in lithium. Ageev et al. interpreted their results on copper and nickel on the basis of bridge electrons corresponding to covalent bonds. On the other hand, other investigations on aluminium, silver, copper, nickel, chromium, etc., do not support the concentration of electron density. Theoretically, it is known that high-temperature factors used to eliminate the termination effect in Fourier series or errors in Fourier coefficients can lead to secondary maxima which could be interpreted as electron concentrations or bridge electrons.