Amorphous functional nanomaterials have drawn a lot of attention due to their unusual physical properties and numerous important applications. Pressure-induced amorphization (PIA) is considered to be a potential way to synthesize new amorphous materials with novel properties. To date, few studies have reported the improved properties of materials after PIA and a wide spectrum of opinions on the PIA mechanism still prevails.
A team of researchers, including Wenge Yang and Lin Wang of HPSynC and Yusheng Zhao of UNLV, reported the PIA in single-crystal Ta2O5 nanowires and the improved performance of the resulting amorphous Ta2O5. Using in-situ high-pressure characterizations and first principles calculations, the scientists explored the pressure-induced local structure evolution within a unit cell and proposed a new crystal-structure related PIA mechanism wherein disruption of connectivity between polyhedra at the particular weak-bonding positions along the elongated a-axis in the unit cell initiated the amorphization.
The researchers also conducted the in-situ high-pressure resistance measurements which revealed that the electrical conductivity of pressure-induced amorphous Ta2O5 nanowires was significantly improved compared to traditional amorphous forms. This study proves that the high-pressure compression is a powerful way to prepare novel amorphous materials which can possess unique properties surpassing those in either crystalline or conventional amorphous phases. It also provides a new perspective for understanding PIA mechanism.Ta2O5 has been widely used in dynamic random access memory devices, capacitor, atomic switch, antireflective coating layer, gas sensor, photocatalysis, among others [X. Lü, et al., J. Am. Chem. Soc. 135, 13947-13953 (2013)].