Concentration quenching, surface and spectral analyses of SrF2:Pr3+ prepared by different synthesis techniques

• SrF2:Pr3+ nano-phosphors were successfully synthesised by hydrothermal and combustion methods.
• The blue–red emission decreased with increasing Pr3+ concentration.
• The reduction in the intensity for higher concentrations was due to dipole–dipole induced concentration quenching effects that resulted from [3P0, 3H4] → [1G4, 1G4] and [3P0, 3H4] → [3H6, 1D2] cross-relaxation processes.

Pr3+ doped strontium fluoride (SrF2) was prepared by hydrothermal and combustion methods. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) spectroscopy. XRD patterns indicated that the samples were completely crystallized with a pure face-centred cubic (space group: Fm3m) structure. SEM images showed different morphologies which is an indication that the morphology of the SrF2:Pr3+ phosphor strongly depends on the synthesis procedure. Both the SrF2:Pr3+ samples exhibit blue–red emission centred at 488 nm under a 439 nm excitation wavelength (λexc) at room temperature. The emission intensity of Pr3+ was also found to be dependent on the synthesis procedure. The blue–red emission has decreased with an increase in the Pr3+ concentration. The optimum Pr3+ doping level for maximum emission intensity was 0.4 and 0.2 mol% for the hydrothermal and combustion samples, respectively. The reduction in the intensity for higher concentrations was found to be due to dipole–dipole interaction induced concentration quenching effects.