Two solids made of the same elements but with different geometric arrangements of the atoms, or crystal phases, can produce materials with different properties. Coal and diamond offer a spectacular example of this effect. Researchers have found that some crystals have an easier time of making a solid-solid transition if they take it in two steps. Surprisingly, the first step of the process involves the parent phase producing droplets of liquid. The liquid droplets then evolve into the daughter phase.
Chips that use light, rather than electricity, to move data would consume much less power -- and energy efficiency is a growing concern as chips' transistor counts rise. Scientists have developed a new technique for building MoS2 light emitters tuned to different frequencies, an essential requirement for optoelectronic chips. Since thin films of material can also be patterned onto sheets of plastic, the same work could point toward thin, flexible, bright, color displays.
The Alpha Magnetic Spectrometer collaboration has just presented its latest results. These are based on the analysis of 41 billion particles detected with the space-based AMS detector aboard the International Space Station. The results provide new insights into the nature of the mysterious excess of positrons observed in the flux of cosmic rays.