Corrosion behavior of different tantalum crystal faces in NH4Br–ethanol solution and DFT calculation

We report different corrosion mechanisms for the (1 1 0), (2 0 0) and (2 1 1) crystal faces of tantalum in NH4Br–ethanol solution. With increasing temperature, the Br-Ta bond was found to readily attract electrons from the [1 1 0] orientation atomic interlayer due to large layer spacing and weak layer-to-layer interaction, resulting in an easily corroded (1 1 0) face. On the other hand, short layer spacing and strong interactions between layers led to passivation of the (2 0 0) and (2 1 1) faces with increasing temperatures, on account of the fact that the Br-Ta bond is unable to easily draw electrons from the atomic inter-layers.