A new method for estimating the dispersity of deposited metallic nanoparticles and extent of their interaction with the support matrices |
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Authors: | F. V. Tuzikov I. É. Beck N. A. Tuzikova V. I. Bukhtiyarov |
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Affiliation: | (1) Departmento de Ingeneria de Materials, (DIMAT), Facultad de Ingenieria, Universidad de Concepcion, Edmundo Larenas 270, Casilla 160 C, Concepcion, Chile |
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Abstract: | Using a fully relativistic DV cluster method, we study the electronic structure of a large fragment of the crystal lattice of zircon ZrSiO4 with a plutonium dopant atom replacing a Zr4+ zirconium atom. Three possible states of the impurity center are considered: Pu4+ (isovalent substitution), Pu3+ (non-isovalent substitution), and Pu3+ with an oxygen vacancy in the nearest environment that provides charge compensation. Relaxation of the ZrSiO4 crystal lattice near a defect is simulated using a semi-empirical method of atomic pair potentials (GULP program). An analysis of overlap populations and effective charges on atoms shows that the chemical bonding of plutonium with a matrix is covalent, while isovalent substitution yields a more stable system than a Pu3+ impurity. In the presence of vacancies the structure of chemical bonding is intermediate with respect to substitutions Pu4+ → Zr4+ and Pu3+ → Zr4+. |
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