Monovalent ions co-doped SrTiO3:Pr3+ nanostructures for visualization of latent fingerprints and as a red component for solid state devices

Abstract

Structural and luminescence properties of SrTiO3: Pr3+: A+ (A+: Li, Na, K) nanophosphors were synthesized by simple sonochemical route. Prepared products were well-characterized for their optical and structural properties. Surface morphology of the prepared samples were studied with the influential parameters such as surfactant concentration, sonication time, temperature, pH and compared the effect with normal mechanical stirring. Morphology was highly dependent on the experimental parameters. The predicted growth mechanism to obtain superstructures of the samples prepared by sonochemical method was discussed. Photoluminescence (PL) studies exhibit characteristic emission peaks of Pr3+ ions in the range 500-750 nm. The highest PL intensity was obtained for 5 mol% of Pr3+ doped samples. Further, co-doping with Li+, Na+ and K+ ion into Pr3+ activated SrTiO3 phosphor led to an enhancement in luminescence intensity by reducing the parity restriction of electric dipole transitions. As a consequence of suitable local distortion of the crystal field surrounding to the Pr3+ activator ions. The maximum PL intensity was observed for Li+ (1 wt %) co-doped SrTiO3:Pr3+ (5 mol %) samples. Furthermore, Li+ ion was the best charge compensator, because of it reduced the defects emission and also increased the emission intensity of Pr3+ significantly. Prepared phosphors exhibit short lifetime, good quantum efficiency; excellent color purity which is near to the NTSC standards. Prepared fluorescent powders were used as a dusting powder for the rapid visualization of latent fingerprints under UV light of 254 nm. From the reported results it is evident that the optimized prepared samples are suitable for solid state lighting and advanced forensic investigation applications.