Each particle is covered with an insulative oxide film which contains {HEAD ~ 0.3 to 0.8%} of oxygen by {TAIL ~ weight} based on the particle 
Each particle is covered with an insulative oxide film which contains { HEAD ~ 0.3 to 0.8 % } of oxygen by { TAIL ~ weight } based on the particle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH