#skoltech

Researchers propose new physical model for predicting hardness of materials

Skoltech researchers have presented a new simple physical model for predicting the hardness of materials based on information about the shear modulus and equations of the state of crystal structures. The model is useful for a wide range of practical applications—all parameters in it can be determined through basic calculations or measured experimentally. The results of the study are presented in the Physical Review Materials journal. Hardness is an important property of materials that determines their ability to resist deformations and other damage (dents, scratches) due to external forces. It is typically determined by pressing the indenter into the test sample, and the indenter must be made of a harder material, usually diamond. In this case, the hardness is determined based on the ratio between the maximum indentation force and the imprint that remains on the sample.

Research reveals best conditions for storing graphene oxide

A research team from Skoltech and other scientific organizations conducted a study to determine which conditions are the most suitable for storing graphene oxide—a promising material that can be used for manufacturing composite materials, gas sensors, and in many other fields. The results show that the most optimal conditions for graphene oxide, when its properties will not change, are low temperatures and a lack of light. The paper was published in the Surfaces and Interfaces journal. Graphene has unique properties and is widely used in electronics, energy storage, and optoelectronics. Obtaining pure graphene in large quantities is not easy and expensive, so it is often replaced with derivatives—for example, graphene oxide (GO). It has high electrical resistance, low thermal conductivity, and high solubility.

Researchers suggest a new method for determining atomic charges in materials

Researchers from Skoltech, Ural Federal University, and Mikheev Institute of Metal Physics, UB RAS, have furnished a fundamental theoretical description of important properties of chemical bonding in materials—namely, the atomic charges and the partitioning of chemical bond energy into ionic and covalent contributions. The research paper provides a compelling groundwork for the traditional picture based on the notion of electronegativity. That said, the study also identifies an anomalous and counterintuitive case: the semiconducting boron phosphide. The findings are reported in The Journal of Chemical Physics. Since the early 20th century, scientists have sought to explain the properties of molecules and crystals in terms of chemical bonds—the attractive interactions between the atoms due to some underlying behavior of their valence electrons.

New ceramics promise hotter gas turbines that produce more power

Skoltech researchers have identified promising ceramic materials for metal coatings that would boost gas turbine efficiency. If further experimental tests prove successful, the coatings will enable power plants to produce more electricity and jet planes to consume less fuel. With the material discovery technique tried and tested, the researchers intend to continue the search and find more candidates with perhaps even better properties. The study is published in Physical Review Materials. Thermal barrier coatings are used to protect turbine blades at power plants and in jet engines. The blades themselves are made of nickel-based superalloys. These offer a great combination of high-temperature strength, toughness, and resistance to degradation. However, as things get really hot, the superalloy softens and may even melt. Protective coatings make it possible to operate turbines at higher temperatures without compromising their integrity. And in this case, higher temperature means greater efficiency.

Study probes unexplored combination of three chemical elements for superconductivity

Skoltech researchers and their colleagues from MIPT and China's Center for High Pressure Science and Technology Advanced Research have computationally explored the stability of the bizarre compounds of hydrogen, lanthanum, and magnesium that exist at very high pressures. In addition to matching the various three-element combinations to the conditions at which they are stable, the team discovered five completely new compounds of hydrogen and either magnesium or lanthanum only. Published in Materials Today Physics, the study is part of the ongoing search for room-temperature superconductors, the discovery of which would have enormous consequences for power engineering, transportation, computers and more. "In the previously unexplored system of hydrogen, lanthanum, and magnesium, we find LaMg3H28 to be the 'warmest' superconductor. It loses electrical resistance below –109°C, at about 2 million atmospheres—not a record, but not bad at all either," the study's principal investigator, Professor Artem R. Oganov of Skoltech, commented.

'Polaroids' help scientists detect hazardous ice on airplane plating

Researchers from Skoltech, MIPT, Russia's State Research Institute of Civil Aviation, the University of North Texas, and York University have simplified and automated the lab procedure used to test anti-icing fluids that ensure safe aircraft takeoff. The findings of the study, which was supported by the Russian Science Foundation, are reported in the journal Cold Regions Science and Technology.

Frost, snow, and ice accumulation on an aircraft adversely affects its handling properties and increases the risk of accidents by distorting the flow of air over the wings, reducing lift, and creating additional drag. To prevent hazardous icing, the aircraft is treated before takeoff with deicing fluids that melt away any ice or snow that have stuck to the metal, and with anti-icing fluids that form a protective film on the plating to prevent further ice formation.

Since anti-icing treatment is so important for ensuring flight safety and there are many factors at play—fluid dilution, ambient temperature and humidity, wind, precipitation, aircraft skin material, etc.—anti-icing agents are frequently tested in labs so as to know their properties in every detail. This is a tedious process that involves a specialist visually inspecting a piece of aluminum plating treated with an anti-icing fluid in a climate chamber that reproduces the necessary weather conditions.