Ural Federal University: Scientists Improved the Properties of a Unique Semiconductor Tenfold
New data on the properties of calcium-copper titanate, a semiconductor capable of storing a lot of energy under the action of an electric field, were obtained by scientists at Ural Federal University. The research was conducted jointly with colleagues from the Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences. According to scientists, the study will develop a number of new elements for microelectronics, as well as create a concept explaining the unique properties of the material. The article was published in the Journal of Physics and Chemistry of Solids.
Dielectric permittivity is a characteristic of materials that do not conduct current. Under the influence of an external electric field, the dielectric is polarized, for example, by the formation of coupled ion pairs, as a result of which the substance accumulates energy, the scientists explained.
Calcium-copper titanate, or ССТО, is a long-known semiconductor that is simultaneously characterized by good electrical conductivity and a giant dielectric permittivity, 1000-10000 times greater than other materials with this effect. Although this property of ССТО is known for more than 20 years, no explanation for this phenomenon has yet been given, experts said.
Scientists from the UrFU and the Institute of Chemical Technology of the UB RAS, having studied a number of ССТО-based oxides, clarified the explanation of its properties and proceeded to create a new concept explaining this phenomenon. In addition, they were able to find a method for treating ССТО at high pressures and temperatures, after which the dielectric permittivity of the material increases tenfold.
“The two main models that explain the ССТО phenomenon are IBLC, which considers the size of the boundaries between the grains that make up the material and the polarization processes in the region of these boundaries as a priority factor in dielectric permittivity, and NBLC, which considers the size of the grains themselves and the polarization processes within them as important. Although our results support the NBLC, we are working on a more general model that takes into account the strengths of both predecessors,” explained Nina Melnikova, Associate Professor at the Department of Condensed Matter Physics and Nanoscale Systems at UrFU.
According to the scientists, the tenfold increase in dielectric permittivity in their experiments was due to an increase in the size of the matter grains. However, the entire body of data obtained does not fit completely into any one model, indicating the need to develop a new explanation for this phenomenon.
“Ceramic products from ССТО processed by our technology have great potential in microelectronics as elements for energy storage with a large temperature range, as a medium for miniature capacitors, or as semiconductor resistors with nonlinear resistance,” said Abdullo Mirzorakhimov, Leading Engineer of the Department of Condensed Matter Physics and Nanoscale Systems at UrFU.
On the basis of these elements, consisting of fine-grain ССТО, as explained by specialists, it is possible to develop new RAM systems and multilayer capacitors, which are widely in demand in modern electronics. Ceramics with coarse grain will be useful in protecting power lines and any electronics from voltage surges.
According to the scientists from the UrFU, the production of the electronics elements proposed by the scientists is fully feasible on the basis of Russian technologies and production facilities.
In the future, the research team intends to continue fundamental work to explain the phenomenon of high dielectric conductivity of the ССТО, as well as to obtain a number of new materials based on it.