Formation and Segregation of a Pd-MgO Solid Solution Studied by X-ray Absorption Spectroscopy

Thermal treatment of Pd nanoparticles or Pd(NH3)(4)(NO3)(2) supported on MgO resulted in the formation of a solid solution of Pd-MgO, as evidenced by Pd Kedge X-ray absorption fine structure (XAFS). The valence of Pd in the Pd-MgO solid solution was determined to be 4+ from the comparison of X-ray absorption near edge structure (XANES) with reference compounds. A characteristic shrinkage of the Pd-O bond distance was observed in comparison with that of the nearest-neighboring Mg-O bond in MgO, which agreed with the density functional theory (DFT) calculations. The two-spike pattern was observed in the dispersion of Pd-MgO owing to the formation and successive segregation of solid solutions above 1073 K.

Automated summary

Thermal treatment of Pd nanoparticles or Pd(NH3)(4)(NO3)(2) supported on MgO resulted in the formation of a solid solution of Pd-MgO. The valence of Pd in the Pd-MgO solid solution was determined to be 4+ from the comparison of XANES with reference compounds. The shrinkage of Pd-O bond distance was observed in comparison with that of the nearest-neighboring Mg-O bond in MgO, which agreed with DFT calculations. The dispersion of Pd-MgO showed a two-spike pattern due to the formation and segregation of solid solutions above 1073 K.