High-Pressure Phase Transitions of Morphologically Distinct Zn₂SnO₄ Nanostructures

Many aspects of nanostructured materials at high pressures are still unexplored. We present here, high-pressure structural behavior of two Zn₂SnO₄ nanomaterials with inverse spinel type, one a particle with size of ∼7 nm [zero dimensional (0-D)] and the other with a chain-like [one dimensional (1-D)] morphology. We performed in situ micro-Raman and synchrotron X-ray diffraction measurements and observed that the cation disordering of the 0-D nanoparticle is preserved up to ∼40 GPa, suppressing the reported martensitic phase transformation. On the other hand, an irreversible phase transition is observed from the 1-D nanomaterial into a new and dense high-pressure orthorhombic CaFe₂O₄-type structure at ∼40 GPa. The pressure-treated 0-D and 1-D nanomaterials have distinct diffuse reflectance and emission properties. In particular, a heterojunction between the inverse spinel and quenchable orthorhombic phases allows the use of 1-D Zn₂SnO₄ nanomaterials as efficient photocatalysts as shown by the degradation of the textile pollutant methylene blue.