Metallic, oxide and metal-oxide composite nano-materials were produced
and their properties were investigated in connection with structural
features mainly by high resolution electron microscopy. The observed m
etallic grain boundaries were not disordered in atomic arrangement. Sh
ort period CSL boundaries frequently appeared. Long period boundaries
were rarely observed. A void was frequently observed at the grain boun
dary triple point. Shape of the void was round. Structural relaxation
at room temperature was detected by positron life time measurement. It
is suggested that the low density of the metallic nano-material is at
tributed not to the low density grain boundary region but to existing
voids. High chemical activity of metal ceramic interface of Bi2Sr2CaCu
3Ox-Ag composite nano-material was expected to give excellent measured
properties such as high Jc and high plasticity.