Measurements of the X-ray absorption fine structure were made in order to probe the local environment around Mn ions in Mn-doped nano-crystals with size distributions ranging from 3.0 to 3.5nm and from 5.0 to 5.5nm. The interatomic distances between Mn and neighboring atoms, the coordination number, the local disorder and the effective valency were determined for the nano-crystals and were compared with those for bulk Mn-doped material. It was found that the Mn ions substituted at Zn sites in the host lattice, but with significant size-dependent local structural changes. The near-edge X-ray absorption fine structures indicated that the effective valency of Mn ions in the nano-crystals was close to +2, with a weak size dependence. These local structures were suggested to be closely related to the optical properties.

Y.L.Soo, Z.H.Ming, S.W.Huang, Y.H.Kao, R.N.Bhargava, D.Gallagher: Physical Review B, 1994, 50[11], 7602-7