Sructure and stability of solid solutions crystal lattice based on zirconium dioxide

Abstract

The goal of research is the study of problems, which are connected with stability of thin film of zirconium dioxide on the surface of fuel rod during operation. This work has been carried out to investigate the possibility of coolant radioactivity reduction, which depends on the hermetic of fuel rod shell. The integrity of this shell depends on many factors, the main one of which is the stability of zirconium dioxide film. There are some kind of phase transitions in this film, which are based on the integral influence of temperature, pressure and radiation. The process of corrosion includes – oxidative and radioactive corrosion. Oxidative corrosion plays the leading role among them and its speed can increase with the presence of radioactive one. The purpose of roentgen-graphic studies of solid solutions based on zirconium dioxide was an obtaining of information regarding the structure of these compounds in conjunction with different additives of ion stabilizers. At the same time, experiments with different samples subjected to annealing at temperature of 950 ºC during different periods were done. Roentgen stud-ies were carried out on the X-ray diffractometer DRON-3.0 in the emission of Kα Fe (λ=0.194 nm). Experimental results show that an addi-tion of stabilizing ions (in certain molar concentrations) Ca, Y, Nd, Sc into the solid solution of zirconium dioxide will lead to the stabiliza-tion of cubic phase. In addition, it draws an attention the redistribution of peaks intensity in all researched systems subjected to the annealing at temperature 1223 K that is close to the temperature of phase transformation from monoclinic structure into tetragonal (1370 K) in the pure zirconium dioxide. This can be evidence of stabilizing ion streamlining at the special nodes of crystalline lattice of the matrix grid. However, it doesn’t lead to the significant change of crystalline lattice parameters and as a result the specific volume of unit cell remains almost with-out change. It means that solid solutions based on zirconium dioxide that have stabilized cubic phase can be used as protective coatings.