Observation of Shock-Induced Phases of Nb₂O₅ Single Crystal under High-Resolution Electron Microscopy

Abstract

Shock-loading experiments on Nb 2 O 5 single crystals were carried out up to 54 GPa by the gun method. The shock-loaded materials are recovered by using both closed and open recovery fixtures and were examined by powder X-ray diffraction analysis and high-resolution electron microscopy. Complete conversion to T-Nb 2 O 5 of µm size, denser by 12% than H-Nb 2 O 5 , was found in the pressure range from 20–40 GPa. When single-crystal H-Nb 2 O 5 was shocked perpendicular to the b -axis using the open-system recovery fixture, an unidentified phase referred to as the X-phase, besides T-Nb 2 O 5 and shock-reduced Nb x O 2 with the rutile structure, was observed. The high-resolution image of the X-phase is interpreted as two-dimensionally disordered H-Nb 2 O 5 . The X-phase is probably formed in the rapid decompression process from the shock-induced high-pressure phase.