Ce 3+ -Doped Li 2 Ca 5 Gd(BO 3 ) 5 Phosphors with Multiple Luminescent Centers and High Pressure Sensitivity under Near UV Excitation

The performance of Ce -based phosphors under mechanical high pressures becomes attractive due to the potential application as a visual pressure sensor. Li Ca Gd(BO ) was selected as the host for the Ce doping. Rietveld refinements reveal that rare earth cations occupy 1, 2, and 3 sites, and indeed, the photoluminescent spectra of Li Ca Gd Ce (BO ) (0.005 ≤ ≤ 0.15) exhibit the characteristic of multiple activators, defined as CeI, CeII, and CeIII, with the maximal emission wavelength at ∼444, 419, and 378 nm, respectively. The optimal internal and external quantum efficiencies are 86.29% for = 0.005 and 20.26% for = 0.10, respectively, under the NUV excitation at 363 nm. In-situ high pressure emission spectra under 375 nm excitation exhibit an overall red-shift, and the linear pressure susceptibilities up to 6.7 GPa for CeI and CeII centers are -390 and -279 cm /GPa, respectively, which is probably the largest among Ce -doped oxides and oxysalts. Due to the above superiorities, Ce -doped LCGB possesses a high potential as a visual pressure sensor, and this is a successful study on the structure-property relationship of inorganic materials.