Abstract
The photoluminescence (PL) characterization spectrum has been widely used to study the electronic energy levels. is one of the commonly used doping elements to provide the PL with concentration limited to 1% atomic ratio. Here, we present a tricolor PL achieved in pyrochlore through pressure treatment at room temperature, which makes a non-PL material to a strong multiband PL material with at the regular lattice site with 18.2% concentration. Under a high pressure compression-decompression treatment up to 78.0 GPa, the undergoes pyrochlore (), to cotunnite (), then amorphous phase transition with different coordinations and site symmetries. The PL emerged from 31.2 GPa when the pyrochlore to cotunnite phase transition took place with the breakdown of site symmetry and enhanced hybridization of and orbitals. Upon decompression, the materials became an amorphous state with a partial retaining of the defected cotunnite phase, accompanied with a large enhancement of red-dominant tricolor PL from the ion pair cross-relaxation effect in the low-symmetry () site, in which two distinct emission centers ( center and center) are present.
- Received 10 June 2020
- Accepted 2 November 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.245701
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