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K2Gd0.97Zr (PO4)3:3mol% Eu3+ were prepared by the solid-state diffusion method and under a vacuum ultra-violet (VUV) region, photoluminescence properties of the phosphor were examined. The phenomenon of visible quantum harvesting via DC was observed in synthesized phosphor for the Gd3+–Eu3+ pair. In the process of quantum harvesting, the two visible light photons are emitted per absorbed VUV photon. This phenomenon occurred upon the 190 nm excitation of Gd3+ at the 6GJ level through a two-step energy transfer from Gd3+ to Eu3+ by cross-relaxation and sequential transfer of the remaining excitation energy. The consequences are that the quantum efficiency of the K2Gd0.97Zr (PO4)3:3mol% Eu3+ phosphor in the energy transfer process from Gd3+ to Eu3+ could reach 233%. The quantum efficiency goes to more than 200% (i.e., 233%) at just low concentration Eu3+ ions (i.e. 3% only). This novelty was found in the prepared phosphor. Therefore, the phosphor K2Gd0.97Zr (PO4)3:3mol% Eu3+ was a potential quantum harvester and potential candidate for mercury free fluorescent lamp and plasma display panel.

The strong vacuum ultraviolet (VUV) radiation absorption and energy transfer mechanism is detected in SrF2: Gd3+, Eu3+ fluoride phosphor. The phosphor is synthesized by a wet chemical method followed by reactive atmospheric process (RAP). The Powder XRD analysis shows structural purity. The photoluminescence characteristics of SrF2:Gd3+, Eu3+ phosphor is studied using the remote access of 4B8 window (VUV beamline) of the Beijing Synchrotron Radiation Facility (BSRF) China. In this paper the mechanism of Energy transfer from the Gd3+ to Eu3+ through the cross relaxation process is investigated. The down-conversion of energy from VUV (142 nm) to visible with quantum efficiency (QE) around 124% has been detected. The PL excitation and emission characteristics of the prepared phosphor advocates it as a prominent material for the applications in mercury free fluorescent lighting (MFFL) & Plasma Display Panel.