High-pressure luminescence of monoclinic and triclinic GdBO3: Eu3+

Abstract

The monoclinic (α) and triclinic (β) GdBO3 submicron-sized crystals doped with Eu3+ ions were synthesized using different approaches (sol-gel Pechini and hydrothermal method). The luminescence properties of these two types of GdBO3 are different due to the different symmetry of the local coordination environment of Eu3+ ions, embedded in the investigated materials. Crystal structures of GdBO3: Eu3+ were investigated using X-ray diffractometry under high-pressure conditions. High-pressure luminescent properties of the monoclinic and triclinic phases were investigated up to about 8 GPa, and they differ for two types of Eu3+-doped GdBO3 crystals. Changes in emission spectra, such as broadening and splitting of bands in the compression cycle are shown for both matrices with Eu3+ ions. The band centroid shifts and Stark sub-level were calculated and correlated with the increase in pressure value. The maximum shifts were 0.25 nm/GPa for the Stark sub-level of the 5D0→7F2 transition in the monoclinic GdBO3: Eu3+, and 0.35 nm/GPa for the Stark sub-level of the 5D0→7F1 transition in the triclinic GdBO3: Eu3+.