Properties of strontium hexaferrite studied by Russian researchers

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Hexaferrites attract a great deal of attention from researchers around the world thanks to their unique physical properties. For several years now, the researchers at South Ural State University have been successfully carrying out works on obtaining and studying the functional properties of this class of magnetic materials. This is one of the most widely used magnetic oxides, which is undoubtedly a material of the future and can be used as a functional element for mechanical engineering and instrumentation engineering.

Magnetic Material – Strontium Hexaferrite

Modern interest in ferrites is tied to the high demand for elements for high frequency electronic component base, which are widely used in modern mechanical engineering, instrumentation engineering, control systems, modern automated production lines, and in the aerospace industry. So, studying the structure and properties of these materials is very important. Researchers from the SUSU Institute of Natural Sciences and Mathematics have completed serious work dedicated to comprehensive study of strontium hexaferrite in powder and multicrystal form.

“The results of our work will be published in the highly-rated Journal of Magnetism and Magnetic Materials, included in the first quartile. In our article, we presented the results of our studies into bulk single crystals and the synthesis of strontium hexaferrite powder. It is important to note that we did not only study the crystal structure of samples, which proved that the materials we had obtained were indeed strontium hexaferrite. We also studied the thermomechanical properties, which are important for practical usage,” says Denis Vinnik, Doctor of Sciences (Chemistry), Head of the Crystal Growth Laboratory of the Nanotechnology Research and Education Centre, Associate Professor of the SUSU Department of Materials Science and Physical Chemistry of Materials.

Unique Properties of Ferrites

Ferrites are ferromagnetic, dielectric, and act as semiconductors. Researchers from South Ural State University have completed a full range of research into the properties of strontium hexaferrite. Temperature stability, magnetic characteristics, mechanical characteristics – all of these characteristics of the material are necessary for practical applications.

“When we talk about application, it is always necessary to consider the particular temperature interval in which the appropriate parameters need to be supported,” explains Denis Vinnik. “And, accordingly, the research that we have done proves that single crystals and powders of strontium hexaferrite have the necessary thermomechanical stability.”

At present, this field is part of the general trend of development in science around the world, but the majority of researchers are working on obtaining polycrystals – nano- and micro-powders of such materials. However, SUSU researchers are successfully growing single crystals and studying their characteristics. Single crystals are interesting for manufacturers in that they are capable of providing high level of quality for the final product, have a wide range of applications, and have a very low level of defects. Bulk single crystal structures of hexaferrites with a significant degree of substitution of iron atoms have only been created at SUSU.

The artificial ferrites that are currently being studied are far from their natural prototypes. Strontium hexaferrite is a promising “high temperature” magnetoelectric.

“We used the well-known matrix of hexagonal ferrite as a base. In the first stage, we developed a methodology of synthesizing this material, studied the chemical composition, structure, and properties. This allowed us to choose the combination of methods necessary to characterize the material. Then, these known synthetic matrices undergo modification to change their properties. We change the chemical composition and change the structure. In the future, this will allow us to change their properties. Our goal is to achieve smooth changes in the characteristics of the material through gradual changes to the structure,” continues Denis Vinnik.

World-class Laboratory Equipment

South Ural State University has everything required for the creation of materials. We have the necessary equipment for synthesis, thanks to which researchers can obtain powders and grow single crystals, and we also have equipment to study the obtained materials. Using an interdisciplinary approach to research makes it possible to solve complex tasks.

“In the Crystal Growth Laboratory of the Nanotechnology REC, we are completing the first characterization, determining the chemical composition, studying the crystal structure, and studying the stability of the obtained materials in a wide range of temperatures and thermomechanical properties,” says Denis Vinnik, providing an example. “It is worth a separate note that recently, SUSU has purchased a magnetometer, and we can now study the magnetic characteristics of our materials. Where earlier we consulted with our colleagues from other institutions, we now can complete all of our work in our own university.”

Article in a highly-rated journal:

Flux single crystal growth of M-type strontium hexaferrite SrFe12O19 by spontaneous crystallization

By Olga Romanovskaia

Photo by Viktoria Matveichuk: Denis A. Vinnik in the SUSU Nanotechnology REC