Pages: 31 - 38

Authors: Yury A. TETERIN, Serguei V. STEFANOVSKIJ, Serguei V. YUDINTSEV, George N. BEK-UZAROV, Anton Yu. TETERIN, Konstantin I. MASLAKOV, and Igor O. UTKIN

Abstract

The synthesis of ceramic matrixes for the long-term storage of highly active radionuclide wastes and determination of physical and chemical forms of radionuclides in them is one of the important problems in radioecology. It enables to create purpose fully materials for the long-term storage of radionuclides. In the present work the samples of ceramics [CaCe_0.9Ti₂O_6.8 (I) and CaCeTi₂O₇ (II)] formed under various conditions were investigated with the X-ray photoelectron spectroscopy. It is necessary for synthesis of ceramic matrixes, for the disposal of the plutonium and others tetravalent actinides. A technique was developed for the determination of cerium oxidation state (Ce³⁺ and Ce⁴⁺) on the basis of the X-ray photoelectron spectroscopy spectral structure characteristics. It was established that the sample (I) formed at 300 MPa and T = 1400°C in the air atmosphere contained on the surface two types of cerium ions in the ratio - 63 atomic % of Ce³⁺ and 37 atomic % of Ce⁴⁺, and the sample (II) formed at 300 MPa and T = 1300°C in the oxygen atmosphere contained on its surface two types of cerium ions also, but in the ratio - 36 atomic % of Ce³⁺ and 64 atomic % of Ce⁴⁺. It was established that on the surface of the studied ceramics carbonates of calcium and/or cerium could be formed under influence of the environment that leads to the destruction of ceramics.

Key words: ceramics, matrix, XPS, cerium, radioactive wastes

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