Young scientist grows hexaferrite crystals implementing gradient substitution
Vladimir Zhivulin, a Senior Researcher at the Crystal Growth Laboratory of South Ural State University, won a grant from the Russian Science Foundation for conducting research on the gradient replacement of iron atoms in crystal structures based on M-type hexaferrite. The creation of such substituted structures opens up new, broadest possibilities for fine-tuning the electrical and magnetic properties of functional materials in the production of modern microwaves and electronic devices.
The current interest in ferrites is caused by the significant demand for elements of the high-frequency electronic component base, which are widely used in modern mechanical engineering and instrument making. Modification of the chemical composition of hexaferrite leads to a change in its properties over a relatively broad range, which makes it possible to adjust the properties of the material to the needs of the industry. Therefore, the study of the structure and properties of such materials is of great importance.
At the Laboratory of Crystal Growth, REC "Nanotechnology" SUSU, scientists receive modified single crystals of barium hexaferrite and, thus, are able to manage their properties. The results of a study of the structure and properties of such materials were published in the highly-rated journal Journal of Magnetism and Magnetic Materials.
"Single crystals are produced from melts of complex composition, including iron and barium oxides (or strontium, or lead), oxides of substituting elements, as well as solvents—boron, sodium oxides, etc., which allow the growth process to be carried out at relatively low temperatures—no more than 1400 degrees. A thorough experimental study of the structure and properties of the crystalline phases obtained in this way, in some cases, demonstrates the formation of not only substituted structures but crystals, in which the degree of iron substitution changes smoothly or stepwise. In fact, the formation of crystalline structures with gradient substitution is observed," says Vladimir Zhivulin, a candidate of physical and mathematical sciences.
A barium hexaferrite single-crystal possesses the property of absorbing electromagnetic waves in a certain relatively narrow frequency range. The implementation of gradient substitution will expand the frequency range of the absorbed electromagnetic radiation or realize with the help of a single crystal the possibility of a smooth change in the absorption frequency. Such materials are of strong interest in the production of microwave electronics.
A scientist at South Ural State University plans to conduct fundamental research aimed at acknowledging how gradient substitution in a single crystal is realized, what factors and how to affect the manifestation of this effect. The information obtained with this, in the long run, will allow modulating the effect of the formation of crystals with gradient substitution, obtaining structures with the necessary parameters.
"Today single crystals are of considerable interest because they can provide a significant level of quality of the finished product, allow a broader range of applications and a minimum number of defects, but the process of producing them is extremely complicated. In the Crystal Growth Laboratory, under the leadership of Dr. Denis Vinnik, works on growing single crystals are being successfully carried out. The volumetric single-crystal structures of hexaferrite from the experimental work carried out within the framework of modifying the structure of barium hexaferrite by replacing iron with various elements were the first in the world to produce M-type polysubstituted ferrite," emphasizes Vladimir Zhivulin.
The results that are planned to be obtained as part of the planned work will serve as the basis for the creation of new functional materials based on gradient M-type hexaferrite crystals that are promising for use in various fields of modern electronics. The project of scientists of the South Ural State University will develop in the direction of the strategy of scientific and technological development of the Russian Federation in terms of the transition to alternative materials.
Provided by South Ural State University