Researchers at the University of Warwick and Oxford University have developed a form of crystal that can deliver highly accurate temperature readings, down to individual milli-kelvins, over a very broad range of temperatures: -120 to +680 degrees centigrade.

The researchers used a “birefringent” crystal which splits light passing through it into two separate rays. Research has already shown that the size of the effect will increase or decrease in proportion to the temperature of the crystal. Therefore, in theory, you could calibrate such crystals to be highly accurate temperature gauges.

However, the use of birefringence in this way has significant problems in practice. This temperature measuring ability of highly birefringent crystals is badly compromised by changes in the thickness and orientation of the crystal. This adds expense to the manufacture and calibration of such crystals and makes them almost unusable in situations where, for example, vibration could alter the orientation of the crystal.

However the Warwick and Oxford researchers have developed a reproducible and low-cost method of modifying the properties of crystalline lithium tantalate so that its birefringence is virtually independent of the crystal’s thickness and position making it resistant to vibration and cheaper to manufacture. In fact, they have made the birefringence almost zero in magnitude in all directions (the material is close to being optically isotropic just like ordinary glass). However, the slightest temperature change induces a rapid increase in birefringence in these materials, making this a reliable, robust and very sensitive method for measuring temperature. The inventors have named their device a Zero-Birefringence Optical Temperature Sensor (Z-BotS) and are currently seeking follow-on funding to develop the device from the bench-top proof-of-concept to a miniaturized commercially-viable package.

(via Research gives crystal clear temperature readings from toughest environments)

Scientists grow nanowire directly on a crystal — and help usher in the next generation of electronics

Growing nanowires vertically has been within our power for some time now, but growing them horizontally, and directly on a surface you might actually want? That’s harder. Researchers at the Weizmann Institute of Science think they’ve figured out the trick, and have coaxed nanowires to grow in nice straight lines on sapphire crystals. This makes the nanowires more directly useful for electronics.

They use miscut C-plane sapphire, which produces a series of parallel nanoscale grooves in the surface of the crystal. Then, using the well established vapor-liquid-solid growth method, the nanowires are teased out along the furrows, resulting in long, horizontal, perfectly aligned wires. In this case the researchers used nickel catalyst nanoparticles to produce galium nitride nanoparticles, which are commonly used in electronics.

(via io9)