The formation and crystal structure of a novel rare-earth compound series,
R3Co29M4B10, have been investigated by electron microscopy, x-ray diffracti
on and Rietveld refinement. R3Co29M4B10 can form for R = La, Ce, Pr,Nd, Sm,
Gd, Ho, Tb, Er, Tm, Dy, Lu and M = Si, Al, Ge, and are isostructral with N
d3Ni29Si4B10.