文摘
High-pressure behaviors of YF3:Eu3+ nanocrystals with an average grain size of 40 nm were investigated by in situ high-pressure synchrotron radiation X-ray diffraction measurements up to 31.1 GPa at ambient temperature. The pressure-induced structural phase transition starts at 11.8 GPa and completes at 23.3 GPa. YF3:Eu3+ nanocrystals with a starting phase of orthorhombic structure transform into a high-pressure phase, which is inferred to be hexagonal structure. The high-pressure structure returned to the orthorhombic phase after release of pressure. The transition pressure is enhanced in nanosized YF3:Eu3+ as compared to submicrometer size samples, which is due to the surface energy differences between submicrometer size and nanosized materials. The nanosized samples of high-pressure phase were easier to compress with smaller bulk modulus than the submicrometer size samples. The photoluminescence properties of YF3:Eu3+ have also been studied in the pressure range from ambient pressure to 25.0 GPa at room temperature. Accompanied by the structure transformation, the Eu3+ ion luminescence from 5D0 鈫?7F1,2,3,4 transition in YF3:Eu3+ nanocrystals emerges obvious changes, which indicate the variation of the local symmetry of Eu3+ ions.