Australian scientists have created the most thermally stable material yet discovered. Made of scandium, aluminum, tungsten and d’oxygen, son volume Remains approximately the same from 4 to 1,000 degrees Kelvin (-269 to +1,126 °C), that is, an amplitude of about 1,400 °C!

vast majority of content Increase in volume with heat, due to the thermal movement of atoms. think for example liquid I’m going up thermometer. Thus the coefficient of each material is Spread Thermal, calculated in Kelvin. 1 cm piece of aluminum³ For example 0.075 mm. from “inflate”³ for an increase of 100 °C, while 1 cm³ water 0.21 cm. will take³ When heated to 100 °C (thermal expansion due to Global warming It is also the main reason for the rise of the oceans).

Rockets that have to withstand extreme temperature variations

All this is very annoying in some applications where the material is very strong temperature variation. rockets for example are exposed to intense cold in space and a extreme warmth During takeoff and landing. Similarly, the Lockheed SR-71 Blackbird spy plane runway was known to spray with fuel at ground temperature, as the fuel tanks were not completely sealed until they overheated during flight. We can also cite transplant Medical devices, which, even when subjected to low thermal dimensions, should not vary in volume at all. en general, Tension Thermal damage eventually damages the material and can cause many problems.

So for many years, scientists have been looking for “materials with zero thermal expansion” (zero thermal expansion, ZTE), the amount of which does not change with temperature. Zerodur, a composite in ceramic which has a nearly zero coefficient of expansion over a thermal range between 20 and 320 °C, is used for example Mirror from binoculars Like VLT in Chile.

an exceptionally low coefficient of thermal expansion

Yet it was coincidental that Neeraj Sharma’s team at the University of New South Wales discovered their new material, ZTe, described in the journal. chemistry of material. « We were conducting experiments for battery-based research, and we were surprised to see the thermal property of this particular structure. », tells the researcher. Ingredients, Exact Formula Sc. with_1.5Ali_0.5woo₃hey₁₂, αv = −6 × 10 . is the thermal expansion coefficient of^-8 K^-1. This means that 1 cm. A piece of³ Only 0.003 mm in volume. will lack³ For a temperature rise of 100 °C! This exceptionally low coefficient can be measured very precisely thanks to the powder diffractometer ofAustralian Organization for Nuclear Science and Technology (ANSTO), which can detect very small deviations.

Optimum rearrangement of atomic bonds

But how to interpret this incredible thermal stability ? « The bond lengths, angles, and positions of the oxygen atoms interact with each other to preserve the total volume. », suggests Neeraj Sharma. In other words, temperature variation produces changes at the molecular level but which do not affect the overall sample size. The role of other compounds is less clear, and will require further investigation.

« Science_1.5Ali_0.5woo₃hey₁₂ can be easily synthesized on a large scaleReassure Neeraj Sharma. and its components such as tungsten oxide andLess are relatively inexpensive. Hence it can be manufactured on a large scale and at a low cost. ».