Krasnoyarsk scientists have developed a simple, environmentally friendly and efficient method for producing CoFe alloy films. They substituted toxic reducing agents with harmless polysaccharides. Films synthesized by the new method are not inferior to those obtained by the conventional technique, and they have high magnetic properties. The research results are published in the journal Semiconductors.

Iron-cobalt alloy films exhibit excellent magnetic properties and are widely used in magnetic recording, magnetic sensors, and coatings. One of the simplest and most economical methods for preparing iron-cobalt alloys is chemical deposition, with reducing compounds being used. However, conventional reducing agents such as hypophosphite or sodium borohydride contaminate the films with impurities deteriorating their magnetic characteristics. Moreover, such reducing agents are toxic.

A team of Krasnoyarsk scientists, including physicists from the Federal Research Center "Krasnoyarsk Science Center SB RAS", modified the chemical method for preparing nanostructured iron-cobalt films using various polysaccharides as reducing agents. Scientists note that the modified method is highly efficient and simple.

The iron-cobalt alloy was synthesized by the chemical deposition method. One of the important components of such a reaction is a reducing agent, which “helps” substances to be reduced to metal, “covering” the surface of the substrate. Scientists used starch, sucrose and arabinogalactan, a polysaccharide obtained from Siberian larch wood, as reducing agents in the reaction. These substances are environmentally friendly, but can affect the characteristics of the resulting material.

Magnetic properties are one of the most important parameters for films. They depend on their morphology, crystal structure and composition. These characteristics, respectively, depend on the iron content and type of reducing agent in the material used to make the film. So, for example, substituting the reducing agent with sucrose led to the fact that the film surface consisted of larger and more faceted metal particles. Arabinogalactan made the surface of the films smooth and uniform.

After the synthesis, scientists conducted magnetic studies of the resulting films. The films obtained using different polysaccharides as reducing agents were characterized by a high coefficient of magnetization threshold and a small amount of carbon impurities. Moreover, the best effect was obtained when using sucrose.

“We were faced with the task of obtaining films in a way which would reduce the impact on the environment. Traditionally, these films are produced using toxic reducing agents. When we substituted traditional chemical reducing agents with carbohydrates, we got films that are not inferior to the known samples in their magnetic characteristics, they have few impurities, they have a high value of magnetization, and at the same time the production process is completely non-toxic, "says Elena Denisova, Candidate of Physical and Mathematical Sciences, senior researcher at the L.V. Kirensky Institute of Physics KSC SB RAS.

This study was supported by the Russian Foundation for Basic Research, Government of the Krasnoyarsk Region and Krasnoyarsk Regional Fund for the Support of Scientific and Technical Activities (project No. 18-42-240006).