A refinement of the parameters of α-manganese

The atomic parameters of 0~ manganese, first determined by Bradley & Thewlis (1927), have been refined from an R index of 0.093 to a final R of 0.029 for fifty reflections.This refinement was based on an analysis of the integrated intensities of X-ray diffracted powder peaks measured independently at two laboratories.The lattice constant of ~ manganese was determined from liquid helium temperature up to room temperature and a change in the thermal expansion coefficient was found in the vicinity of the N6el temperature (95 °K) although no structural change was observed in this region.The structure of ~ manganese as determined by Bradley & Thewlis (1927) is as follows:Space group 17~3m no.217 in International Tables for X-ray Crystallography (1952).2 Mn(1) in 2(a) 000, etc. 8 Mn(2) in 8(c) xxx, etc. x(2)=0.31724 Mn(3) in 24(g) xxz, etc. x(3)=0-356, z(3)=0.04224 Mn(4) in 24(g) xxz, etc. x(4) = 0"089, z(4)= 0"278