Category Chemistry/Nanotechnology

Changes in colors emitted through mechanochromism a) When the blue crystal in emission was ground at the center, the color turned yellow. b) A round filter paper thinly coated with blue mechanochromic molecules in emission. The yellowish letters “Au” appeared after scratching the surface with a spatula. Credit: Image courtesy of Hokkaido University

In mechanochromism, certain solid and liquid crystalline materials change their photoluminescence properties upon mechanical stimulation, such as grinding, ball-milling and crushing. Although such compounds have attracted much attention with hopes of various applications, it has heretofore been thought difficult to synthesize mechanochromic compounds with desired emission properties and behaviors as each molecule emits different color.

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A thermal probe tests heat conductance in a sample of silicon dioxide nanoparticles. The material could potentially conduct heat at an efficiency higher than that of conventional materials. Credit: Rob Felt, Georgia Tech

Not beach sand, but silicon dioxide nanoparticles coated with a high dielectric constant polymer can inexpensively provide improved cooling for increasingly power-hungry electronic devices. The silicon dioxide doesn’t do the cooling itself. Instead, the unique surface properties of the coated nanoscale material conduct the heat at potentially higher efficiency than existing heat sink materials. The theoretical physics is complicated, involving nanoscale electromagnetic effects created on the surface of the tiny silicon dioxide particles acting together.

The bottom line cou...

The influence of plasmonic hotspots on Au nanoprism growth.

Uni of Florida team has figured out how gold can be used in crystals grown by light to create nanoparticles, a discovery that has major implications for industry and cancer treatment and could improve the function of drugs, medical equipment and solar panels. Nanoparticles can be “grown” in crystal formations with special use of light, ie plasmon-driven synthesis. However, scientists have had limited control unless they used silver, but silver limits the uses for medical technology. The team is the first to successfully use gold, which works well within the human body, with this process.

Gold is highly desired for nanotechnology because it is malleable, does not react with oxygen and conducts heat well...

Three types of large-area solar cells made out of two-dimensional perovskites. At left, a room-temperature cast film; upper middle is a sample with the problematic band gap, and at right is the hot-cast sample with the best energy performance. Credit: Los Alamos National Laboratory

In a step that could bring perovskite crystals closer to use in the burgeoning solar power industry, researchers have tweaked their crystal production method and developed a new type of 2D layered perovskite with outstanding stability and more than triple the material’s previous power conversion efficiency.

“Crystal orientation has been a puzzle for more than two decades, and this is the first time we’ve been able to flip the crystal in the actual casting process,” said Hsinhan Tsai, a Rice graduate student at L...