Russian Scientists Have Created an Environmentally Friendly Material for Sensors

Researchers at South Ural State University, being part of an international team of scientists, have synthesized ceramic material that is suitable for creating pressure, temperature, electric and magnetic field sensors. The material is more environmentally friendly compared to its analogues and belongs to the class of multiferroics. The experiments made it possible to study the features of changes in the crystal structure and physical properties of such materials in phase transitions. An article on the development of ceramic materials with desired properties through chemical substitution of ions was published in one of the most prestigious journals of the first quartile Nanomaterials.

Eco-friendly sensor materials

Recent studies in the field of materials science are aimed at studying the properties and structure of multiferroics. These materials simultaneously have magnetic and electrical ordering, so that their electrical properties can be controlled by magnetic action and vice versa.

For mass production, the main goal for today is to find an inexpensive and convenient material that has magnetoelectric interaction, polarization, magnetization, and at the same time meets environmental standards. Many modern materials contain lead, but its extensive use causes environmental pollution and negative effects on human health.

Scientists involved in the development of modern materials at the South Ural State University believe that ceramic based on bismuth ferrite satisfies modern requirements. The preparation of materials in the form of ceramics makes it possible to relatively quickly synthesize compositions with various chemical substitutions of the starting ions and evaluate the effect of chemical substitution on the structure, and on the properties of such materials.

The research team, which included representatives of SUSU Dmitry Karpinsky, Sergey Trukhanov and Alexei Trukhanov, made this conclusion, working with materials based on bismuth ferrite (BiFeO3), one of the most promising multiferroics. Substituting iron and bismuth ions, scientists studied the structural phase transitions of  BiFeO3-BaTiO3 ceramics and found how the properties of the material change depending on the type of structural distortion. The data obtained will allow the development of new functional materials based on complex oxide systems.

“We used innovative chemical substitution schemes for the synthesis of materials. The selection of the chemical composition made it possible to synthesize ceramic compositions with the so-called metastable structural state. These materials are highly sensitive to external factors, such as temperature, electric and magnetic fields, and pressure. That is, they can be used as sensors of external influences,”, a senior researcher at the Department of Materials Science, Physical and Chemical Properties of Materials (the Faculty of Materials Science and Metallurgical Engineering, Institute of Engineering and Technology) Dmitry Karpinsky explained.

Photo: temperature sensors

Together with scientists from SUSU, the study involved representatives of the Ural Federal University, Lodz University of Technology (Poland), and the University of Aveiro (Portugal). In foreign scientific centers, experiments such as studying the structure of material compositions by electron and atomic force microscopy and others were performed. SUSU conducted an analysis of the structure of the compositions by the method of x-ray diffraction.

From bulk ceramics to thin films

At the end of the study, scientists revealed a relationship between the type and magnitude of structural distortions depending on the concentration of substitution ions. It determined the piezoelectric properties (polarization of the material under the action of mechanical stresses). Data were obtained for a wide range of temperatures and concentrations of substitution ions. Based on the results obtained, a phase diagram was made.

Photo: Structural phase diagram of Bi1-xBaxFe1-xTixO3 compositions with 0 <x <0.5, phase boundaries are shown by dashed lines, the region attributed to the enhancement of rhombohedral distortion is marked as R +.

“After choosing the optimal equivalent schemes and a thorough analysis of the structure and properties of the materials obtained, work will be carried out to obtain the already known chemical compositions in the form of thin films, since mostly this form of the material is in demand by the industry. Of course, it is too early to talk about mass  production, but as part of the development of the technology, we plan to get trial batches of materials, which will allow us to assess the prospects of such materials on the market and the scalability of this synthesis technology,”  Dmitry Karpinsky added.

Materials synthesized by the scientists can be used to create sensors for external factors, as well as magnetostrictive and piezoelectric elements.

Research in the field of materials science is one of the three strategic directions for the development of scientific and educational activities of South Ural State University along with IT and ecology.

SUSU is a participant in the 5-100 Project, intended to increase the competitiveness of Russian universities among the world's leading research and educational centers.