High-pressure bandgap engineering and amorphization in TiNb₂O₇ single crystals

Abstract

Titanium niobate (TiNb2O7) possesses excellent photocatalytic, dielectric properties, and lithium-insertion capacity. And high-pressure (HP) is a powerful tool for bandgap engineering aiming at widening their applications. Herein, we report the...

Pressure-Dependent Structural and Band Gap Tuning of Semiconductor Copper(I) Thiocyanate (CuSCN)

“…Meanwhile, in the decompressed sample (Figure 5d), the arc diffraction pattern imposed on a diffuse halo, further suggesting the amorphous feature of the obtained structure. 26 These findings showed that CuSCN transformed from the crystalline phase to amorphous form, confirming the irreversible amorphization transition, which is in line with the Raman and IR results.…”

“…In contrast, the modes at 111 and 430 cm –1 are found to shift toward lower wavenumbers with increasing pressure, indicating that the Cu–N/SCN bonds elongate under pressure . This is probably due to the fact that when applying pressure, the bridge SCN bonds are more readily bent, leading to the rotation of the CuNS 3 tetrahedron without damaging its configuration . Namely, when the CuNS 3 tetrahedron was compressed, the Cu–N/SCN bonds were stretched, leading to a transition of CuSCN from the β phase to the α phase.…”

“…25 This is probably due to the fact that when applying pressure, the bridge SCN bonds are more readily bent, leading to the rotation of the CuNS 3 tetrahedron without damaging its configuration. 26 Namely, when the CuNS 3 tetrahedron was compressed, the Cu−N/SCN bonds were stretched, leading to a transition of CuSCN from the β phase to the α phase. At above 6 GPa, all Raman modes shift up to higher frequencies in lower rates until 12 GPa.…”