High-pressure bandgap engineering and amorphization in TiNb2O7 single crystals

Titanium niobate (TiNb2O7) possesses excellent photocatalytic properties, dielectric properties, and lithium-insertion capacity. High-pressure (HP) treatment is a powerful tool for bandgap engineering aiming at widening its applications. Herein, we report the growth of TiNb2O7 single crystals by the optical floating zone (OFZ) method and the engineering of the TiNb2O7 bandgap via HP. To obtain the physical mechanism of the bandgap variation under HP, the detailed pressure-dependent properties and structure information have been characterized by using in situ Raman spectroscopy and angle dispersive synchrotron radiation X-ray diffraction (ADXRD). During compression, the TiNb2O7 crystals were amorphized and the amorphized phase was maintained under ambient conditions. The microstructures of the uncompressed crystalline and decompressed amorphized samples have also been investigated accordingly.

Automated summary

In this study, TiNb2O7 single crystals were grown by the optical floating zone method and the bandgap of TiNb2O7 was modified through high-pressure engineering. The pressure-dependent properties and structure information of TiNb2O7 crystals under compression were characterized using in situ Raman spectroscopy and angle dispersive synchrotron radiation X-ray diffraction. The crystals became amorphous during compression and remained amorphous under ambient conditions.