Exploring the optical properties of La2Hf2O7:Pr3+ nanoparticles under UV and X-ray excitation for potential lighting and scintillating applications. (10th May 2018)

• Record Type: Journal Article
• Authors: Zuniga, Jose P.; Gupta, Santosh K.; Pokhrel, Madhab; Mao, Yuanbing
• Is Part Of: New journal of chemistry. Volume 42:Number 12(2018)
• Page Start: 9381
• Page End: 9392
• Publication Date: 2018-05-10
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c8nj00895g
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : New optical material of La2 Hf2 O7 :Pr 3+ nanoparticles with efficient luminescence and scintillating properties have drawn a great deal of attention due to the demand for optoelectronic devices and medical theranostics. Abstract : New optical materials with efficient luminescence and scintillation properties have drawn a great deal of attention due to the demand for optoelectronic devices and medical theranostics. Their nanomaterials are expected to reduce the cost while incrementing the efficiency for potential lighting and scintillator applications. In this study, we have developed praseodymium-doped lanthanum hafnate (La2 Hf2 O7 :Pr 3+ ) pyrochlore nanoparticles (NPs) using a combined co-precipitation and relatively low-temperature molten salt synthesis procedure. XRD and Raman investigations confirmed ordered pyrochlore phase for the as-synthesized undoped and Pr 3+ -doped La2 Hf2 O7 NPs. The emission profile displayed the involvement of both the 3 P0 and 1 D2 states in the photoluminescence process, however, the intensity of the emission from the 1 D2 states was found to be higher than that from the 3 P0 states. This can have a huge implication on the design of novel red phosphors for possible application in solid-state lighting. As a function of the Pr 3+ concentration, we found that the 0.1%Pr 3+ doped La2 Hf2 O7 NPs possessed the strongest emission intensity with a quantum yield of 20.54 ± 0.1%. The concentration quenching, in this case, is mainly induced by the cross-relaxation process 3 P0 + 3 H4 → 1 D2 + 3 H6 . Emission kinetics studies showed that the fast decaying species arise because of the Pr 3+ ions occupying the Hf 4+ sites, whereas the slow decaying species can be attributed to the Pr 3+ ions occupying the La 3+ sites in the pyrochlore structure of La2 Hf2 O7 . X-ray excited luminescence (XEL) showed a strong red-light emission, which showed that the material is a promising scintillator for radiation detection. In addition, the photon counts were found to be much higher when the NPs are exposed to X-rays when compared to ultraviolet light. Altogether, these La2 Hf2 O7 :Pr 3+ NPs have great potential as a good down-conversion phosphor as well as scintillator material.