8-Apr-2019: Elements can be solid and liquid at same time
Scientists have discovered a new state of physical matter in which atoms can exist as both solid and liquid simultaneously.
Applying high pressures and temperatures to potassium - a simple metal - creates a state in which most of the element's atoms form a solid lattice structure. However, the structure also contains a second set of potassium atoms that are in a fluid arrangement.
Under the right conditions, over half a dozen elements - including sodium and bismuth - are thought to be capable of existing in the newly discovered state.
Until now, it was unclear if the unusual structures represented a distinct state of matter, or existed as transition stages between two distinct states.
A team led by scientists from the University of Edinburgh used powerful computer simulations to study the existence of the state - known as the chain-melted state. Simulating how up to 20,000 potassium atoms behave under extreme conditions revealed that the structures formed represent the new, stable state of matter.
Applying pressure to the atoms leads to the formation of two interlinked solid lattice structures. Chemical interactions between atoms in one lattice are strong, meaning they stay in a solid form when the structure is heated, while the other atoms melt into a liquid state.
Potassium is one of the simplest metals we know, yet if you squeeze it, it forms very complicated structures. Scientists have shown that this unusual but stable state is part solid and part liquid. Recreating this unusual state in other materials could have all kinds of applications.
13-Feb-2019: Selenium nanoparticles may act like antibacterial agents
Scientists have found that nanoparticles of selenium, an essential micronutrient, can be used as an antibacterial agent.
Selenium is found naturally in wheat, eggs, cheese, nuts and sea food. It is an antioxidant and immunity booster. Scientists found that selenium nanoparticles, owing to their unique structure and properties, may be more effective than antibiotics as they have a larger surface area and therefore can be more in contact with the external environment.
The antibacterial effect may be due to the fact that at a particular concentration nano-selenium interacts with the bacterial cell surface and penetrates into the cell, thus causing damage. Selenium in excess is toxic. Though silver nanoparticles are also being used for similar purposes, researchers chose selenium due to their stable nature.
Selenium nanoparticles were made by combining sodium selenite with vitamin C. As the most easily observed property of nanoparticles is their colour change at different sizes, researchers allowed the process to continue till a colour change was seen. Thereafter, a high-speed centrifuge was used to separate selenium nanoparticles in the form of pellets from the solution.
To confirm whether the newly-produced selenium was actually selenium, the sample was matched in structure, function and properties associated with selenium, using various methods. These artificially-made particles are spherical in shape with average diameter range between 15 and 18 nanometers. The vitamin C used during the process helps in maintaining better uniformity of the particles
Nano-selenium can be an alternative to antibiotics like ampicillin to prevent and treat a number of bacterial diseases or infections in human. The study has also indicated that nano-selenium is 60 times more effective in fighting infections caused by S. aureus, E.coli and P. aeruginosa than conventional treatments. However, more research needs to be carried out to deduce the antimicrobial response of the disease causing microorganisms.
25-May-2018: Ruthenium found to have unique magnetic properties at room temperature
A new experimental discovery demonstrates that the chemical element ruthenium (Ru) is the 4th single element to have unique magnetic properties at room temperature. The discovery could be used to improve sensors, devices in the computer memory and logic industry, or other devices using magnetic materials.
The use of ferromagnetism, or the basic mechanism by which certain materials (such as iron) form permanent magnets or are attracted to magnets, reaches back as far as ancient times when lodestone was used for navigation. Since then only three elements on the periodic table have been found to be ferromagnetic at room temperature -- iron (Fe), cobalt (Co), and nickel (Ni). The rare earth element gadolinium (Gd) nearly misses by only 8 degrees Celsius.
Magnetic materials are very important in industry and modern technology and have been used for fundamental studies and in many everyday applications such as sensors, electric motors, generators, hard disk media, and most recently spintronic memories. As thin film growth has improved over the past few decades, so has the ability to control the structure of crystal lattices - or even force structures that are impossible in nature. This new study demonstrates that Ru can be the fourth single element ferromagnetic material by using ultra-thin films to force the ferromagnetic phase.
The ability to manipulate and characterize matter at the atomic scale is the cornerstone of modern information technology.
Magnetic recording is still the dominant player in data storage technology, but magnetic based random-access memory and computing is beginning to take its place. These magnetic memories and logic devices put additional constraints on the magnetic materials, where data is stored and computed, compared to traditional hard disk media magnetic materials. This push for novel materials has led to renewed interest in attempts to realize predictions which show that under the right conditions, non-ferromagnetic materials, such as Ru, palladium (Pd) and osmium (Os) can become ferromagnetic.
Building upon the established theoretical predictions, researchers at the University of Minnesota used seed layer engineering to force the tetragonal phase of Ru, which prefers to have a hexagonal configuration, and observed the first instance of ferromagnetism in a single element at room temperature.
From an application perspective, Ru is interesting because it is resistant to oxidation, and additional theoretical predictions claim it has a high thermal stability - a vital requirement for scaling magnetic memories. Examination of this high thermal stability is the focus of ongoing research at the University of Minnesota.