Experimental and Theoretical Compton Profiles of Calcium at Room and High Temperature

Abstract

Isotropic Compton profiles of polycrystalline calcium in the f.c.c. (room temperature) and b.c.c. structure (525 °C) have been measured in situ with an 241 Am 59.54 keV γ-ray spectrometer. The band structure, electron momentum density and directional Compton profiles of Ca (b.c.c.) have been calculated and discussed by means of a self-consistent augmented-plane-wave method within the local-density approximation. A comparison of the experimental absolute Compton profiles with the theoretical calculations previously reported for the f.c.c. structure and the new ones for the b.c.c. structure exhibits a good quantitative agreement within 3 to 4% of the J(0) value. Experimental and theoretical differences between the Compton profiles in the two structures are within 1% and 0.5% of the J(0) value, indicating that the isotropic electron momentum density is relatively insensitive to this structural phase transition.