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Charge transfer band (CTB) transition significantly improves the photoluminescence properties of phosphor materials due to its higher absorption efficiency than the characteristic excitations of rare-earth ions. La 2 Zr 2 O 7 (LZO): Pr3+ phosphors with varying doping concentrations of Pr3+ were synthesized through the hydrothermal method. The formation of the pure pyrochlore phase was confirmed from powder X-ray diffraction (XRD). The structural analysis was performed from Rietveld refinement of the XRD data. Field emission electron microscope (FESM) equipped with EDX spectroscopy was used to study the surface morphology and elemental compositions. X-ray photoelectron spectroscopy (XPS) analysis of the optimized sample provides the bonding state of the compositions. Under 257 nm CTB excitation, the photoluminescence emission spectra (PL) exhibit all the characteristic emission peaks of Pr3+ ion. The transitions involved in the excitation and emission process have been shown in the energy level diagram of Pr3+ ions. The Concentration quenching effect was explained from Bless relation and Dexter energy transfer theory between activator ions. Decay curves of the prepared phosphors show bi-exponential behavior. The up-conversion emission spectra were recorded under 980 nm laser excitation. The optical transition in the UV–Vis range was investigated based on the diffuse reflectance spectra, and the results match well with the excitation spectra. The photometric study informs the color and the quality of the emitted light. The outcomes produce a new synthesis method to prepare La 2 Zr 2 O 7 :Pr3+ nano phosphor that can be an excellent candidate for solid-state lighting and UV/NIR to the visible converter in solar cell applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Ceramic phosphors of pure, Dy3+ doped, and Li+ co-doped SrWO 4 have been prepared by solid state reaction route. The structural investigation was conducted with X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and Field emission scanning electron microscope (FESEM). The XRD results verify the phase purity and the crystallinity of the synthesized materials and the vibrational bands of SrWO 4 lattice are confirmed by FTIR. FESEM images show the irregular spherical morphology of the material. However, the particles get agglomerated after the doping of Dy3+ and Li+ ions. The optical measurement was conducted with UV–Visible and Photoluminescence spectrophotometer. The photoluminescence emission spectra contain two bright peaks at 480 nm and 575 nm and a faint peak at 665 nm under 351 nm excitation. The optimum emission is obtained at 2 mol% doping of Dy3+ions. The emission intensity is increased up to three times with the incorporation of Li+ ion. The photometric study reveals that the material emits white and yellow lights. The temperature dependent photoluminescence studied within the temperature range of 77 K–475 K demonstrates that the emission at higher temperatures is much intense than that at room temperature. Therefore, the above material can be developed as a phosphor for application in display devices and LEDs above room temperature. [Display omitted] • SrWO 4 : Dy3+/Li+ phosphors are synthesized by solid state reaction route. • The emission intensity is enhanced three times with the incorporation of Li + ions. • The material shows the abnormal temperature dependent photoluminescence emission. • The emission intensity at 475 K is almost 5 times the emission intensity at 300 K. [ABSTRACT FROM AUTHOR]