Nanometre-sized tungsten (W) clusters were prepared on MgO(001) single
crystalline films using vacuum deposition by burning of a thin W wire
. The structure was studied by high-resolution electron microscopy and
electron diffraction. The clusters had a b.c.c. structure, but not th
e A-15 structure which is known as the stable form for small particles
of b.c.c. metals. This result is due to the strong interaction betwee
n W and MgO(001) substrates. The position of the misfit dislocations a
t the interface is discussed in relation to the growth centre of the W
clusters. Clusters composed of four and five atoms were also detected
in the high-resolution images. The image simulation of the clusters s
uggests that it is possible to determine the adsorption site of W atom
s and the inner structure of the clusters from the image contrast.