A unified microscopic understanding of pressure-dependent bandgap evolution in tellurate oxides remains lacking. Here, we report a pronounced nonmonotonic bandgap evolution in Cu₃TeO₆ up to ~60 GPa, featuring initial widening followed by an abrupt collapse. Two structural transitions (Ia → Ibca → P2/m) are identified by synchrotron XRD and Raman spectroscopy. The bandgap evolution is governed by competing octahedral tilting and Cu-O bond compression, which regulate Cu-O wavefunction overlap. These results provide a general framework for rational bandgap control in tellurate oxides.

 

Multiferroic oxide,high pressure,Raman spectroscopy,UV-vis absorption spectroscopy,Synchrotron XRD